Java/JPA/Inheritance — различия между версиями

Текущая версия на 07:22, 1 июня 2010

Содержание

1 Change Inheritance Type In Hierarchy
2 Inheritance Type JOINED
3 Inheritance Type TABLE_PER_CLASS
4 Lifecycle CallBack: Add Listener To Subclass
5 Lifecycle CallBack Exclude Superclass Listeners
6 Many To One Mapping In Mapped Super class
7 Map Each Class In Hierarchy To Its Own Table
8 Map Hierarchical Data
9 Map One POJO To Multiple Tables
10 Set Discriminator Column: Discriminator Type INTEGER
11 Set Discriminator Value
12 Set Inheritance And discriminator Column
13 Single Table Inheritance
14 Using Mapped Super class

Change Inheritance Type In Hierarchy

File: BadProfessor.java

import javax.persistence.Column;
import javax.persistence.Entity;
@Entity 
public class BadProfessor extends CompanyProfessor {
    private long salary;
    @Column(name="PENSION")
    private long pensionContribution;
    
    public long getPensionContribution() {
        return pensionContribution;
    }
    
    public void setPensionContribution(long pension) {
        this.pensionContribution = pension;
    }
    
    public long getSalary() {
        return salary;
    }
    
    public void setSalary(long salary) {
        this.salary = salary;
    }
    public String toString() {
        return "FullTimeProfessor id: " + getId() + " name: " + getName();
    }
}

File: CompanyProfessor.java

import javax.persistence.Entity;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.Table;
@Entity
@Table(name="COMPANY_EMP")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
public abstract class CompanyProfessor extends Professor {
    private int vacation;

    public int getVacation() {
        return vacation;
    }
    public void setVacation(int vacation) {
        this.vacation = vacation;
    }
}

File: Professor.java
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity
@Table(name="EMP")
@Inheritance(strategy=InheritanceType.JOINED)
@DiscriminatorColumn(name="EMP_TYPE")
public abstract class Professor {
    @Id private int id;
    private String name;
    @Temporal(TemporalType.DATE)
    @Column(name="S_DATE")
    private Date startDate;

    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    public Date getStartDate() {
        return startDate;
    }
    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName();
    }
}

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public void createProfessor(Professor emp) {
    em.persist(emp);
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    BadProfessor emp2 = new BadProfessor();
    emp2.setId(2);
    emp2.setName("bad");
    
    service.createProfessor(emp2);
    System.out.println("Professors: ");
    for (Professor emp1 : service.findAllProfessors()) {
      System.out.print(emp1);
    }
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}


File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Inheritance Type JOINED

File: BadProfessor.java

import javax.persistence.Column;
import javax.persistence.Entity;
@Entity 
public class BadProfessor extends CompanyProfessor {
    private long salary;
    @Column(name="PENSION")
    private long pensionContribution;
    
    public long getPensionContribution() {
        return pensionContribution;
    }
    
    public void setPensionContribution(long pension) {
        this.pensionContribution = pension;
    }
    
    public long getSalary() {
        return salary;
    }
    
    public void setSalary(long salary) {
        this.salary = salary;
    }
    public String toString() {
        return "FullTimeProfessor id: " + getId() + " name: " + getName();
    }
}

File: CompanyProfessor.java

import javax.persistence.Entity;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.Table;
@Entity
@Table(name="COMPANY_EMP")
@Inheritance(strategy=InheritanceType.SINGLE_TABLE)
public abstract class CompanyProfessor extends Professor {
    private int vacation;

    public int getVacation() {
        return vacation;
    }
    public void setVacation(int vacation) {
        this.vacation = vacation;
    }
}

File: Professor.java
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity
@Table(name="EMP")
@Inheritance(strategy=InheritanceType.JOINED)
@DiscriminatorColumn(name="EMP_TYPE")
public abstract class Professor {
    @Id private int id;
    private String name;
    @Temporal(TemporalType.DATE)
    @Column(name="S_DATE")
    private Date startDate;

    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    public Date getStartDate() {
        return startDate;
    }
    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName();
    }
}

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public void createProfessor(Professor emp) {
    em.persist(emp);
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    BadProfessor emp2 = new BadProfessor();
    emp2.setId(2);
    emp2.setName("bad");
    
    service.createProfessor(emp2);
    System.out.println("Professors: ");
    for (Professor emp1 : service.findAllProfessors()) {
      System.out.print(emp1);
    }
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}


File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Inheritance Type TABLE_PER_CLASS

File: BadProfessor.java

import javax.persistence.AttributeOverride;
import javax.persistence.AttributeOverrides;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Table;
@Entity
@Table(name="BAD_EMP")
@AttributeOverrides({
    @AttributeOverride(name="name", column=@Column(name="FULLNAME")),
    @AttributeOverride(name="startDate", column=@Column(name="SDATE"))
})
public class BadProfessor extends Professor {
    @Column(name="D_RATE")
    private int dailyRate;
    private int term;
    
    public int getDailyRate() {
        return dailyRate;
    }
    
    public void setDailyRate(int dailyRate) {
        this.dailyRate = dailyRate;
    }
    
    public int getTerm() {
        return term;
    }
    
    public void setTerm(int term) {
        this.term = term;
    }
    public String toString() {
        return "ContractProfessor id: " + getId() + " name: " + getName();
    }
}

File: Professor.java
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)
public abstract class Professor  {
    @Id private int id;
    private String name;
    @Temporal(TemporalType.DATE)
    @Column(name="S_DATE")
    private Date startDate;
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    public Date getStartDate() {
        return startDate;
    }
    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName();
    }
}

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public void createProfessor(Professor emp) {
    em.persist(emp);
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    BadProfessor emp2 = new BadProfessor();
    emp2.setId(2);
    emp2.setName("bad");
    
    service.createProfessor(emp2);
    System.out.println("Professors: ");
    for (Professor emp1 : service.findAllProfessors()) {
      System.out.print(emp1);
    }
    util.checkData("select * from BAD_EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}


File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Lifecycle CallBack: Add Listener To Subclass

File: ContractProfessor.java

import javax.persistence.Column;
import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
import javax.persistence.EntityListeners;
import javax.persistence.ExcludeSuperclassListeners;
import javax.persistence.PrePersist;
import javax.persistence.Table;
@Entity
@Table(name="CONTRACT_EMP")
@DiscriminatorValue("1")
@ExcludeSuperclassListeners
@EntityListeners(ProfessorDebugListener.class)
public class ContractProfessor extends Professor {
    @Column(name="D_RATE")
    private int dailyRate;
    private int term;
    
    @PrePersist
    public void verifyTerm() { 
        System.out.println("ContractProfessor.verifyTerm called on employee: " + getId());
    }
    public int getDailyRate() {
        return dailyRate;
    }
    
    public void setDailyRate(int dailyRate) {
        this.dailyRate = dailyRate;
    }
    
    public int getTerm() {
        return term;
    }
    
    public void setTerm(int term) {
        this.term = term;
    }
    public String toString() {
        return "ContractProfessor id: " + getId() + " name: " + getName();
    }
}

File: Professor.java

import java.util.Date;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.DiscriminatorType;
import javax.persistence.Entity;
import javax.persistence.EntityListeners;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.PostLoad;
import javax.persistence.PostPersist;
import javax.persistence.PostUpdate;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.persistence.Transient;
@Entity
@Table(name="EMP")
@Inheritance(strategy=InheritanceType.JOINED)
@DiscriminatorColumn(name="EMP_TYPE", discriminatorType=DiscriminatorType.INTEGER)
@EntityListeners(ProfessorDebugListener.class)
public abstract class Professor {
    @Id private int id;
    private String name;
    @Temporal(TemporalType.DATE)
    @Column(name="S_DATE")
    private Date startDate;
    @Transient private long syncTime;
    @PostPersist
    @PostUpdate
    @PostLoad 
    private void resetSyncTime() { 
        System.out.println("Professor.resetSyncTime called on employee: " + getId());
        syncTime = System.currentTimeMillis(); 
    }
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    public Date getStartDate() {
        return startDate;
    }
    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName();
    }
}

File: ProfessorDebugListener.java
import javax.persistence.PostPersist;
public class ProfessorDebugListener {
  @PostPersist
  public void auditNewHire(Professor emp) { 
      System.out.println(" called on employee: " + emp.getId());
  }
}

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public Professor createProfessor(int id, String name) {
    Professor emp = new ContractProfessor();
    emp.setId(id);
    emp.setName(name);
    em.persist(emp);
    return emp;
  }
  public void removeProfessor(int id) {
    Professor emp = findProfessor(id);
    if (emp != null) {
      em.remove(emp);
    }
  }
  public Professor changeProfessorName(int id, String newName) {
    Professor emp = findProfessor(id);
    if (emp != null) {
      emp.setName(newName);
    }
    return emp;
  }
  public Professor findProfessor(int id) {
    return em.find(Professor.class, id);
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    service.createProfessor(1, "name");
    for (Professor emp : service.findAllProfessors()) {
      System.out.print(emp);
    }
    service.changeProfessorName(1, "newname");
    for (Professor emp : service.findAllProfessors()) {
      System.out.print(emp);
    }
    service.removeProfessor(1);
    for (Professor emp : service.findAllProfessors()) {
      System.out.print(emp);
    }
    util.checkData("select * from CONTRACT_EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}



File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Lifecycle CallBack Exclude Superclass Listeners

File: ContractProfessor.java

import javax.persistence.Column;
import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
import javax.persistence.EntityListeners;
import javax.persistence.ExcludeSuperclassListeners;
import javax.persistence.PrePersist;
import javax.persistence.Table;
@Entity
@Table(name="CONTRACT_EMP")
@DiscriminatorValue("1")
@ExcludeSuperclassListeners
@EntityListeners(ProfessorDebugListener.class)
public class ContractProfessor extends Professor {
    @Column(name="D_RATE")
    private int dailyRate;
    private int term;
    
    @PrePersist
    public void verifyTerm() { 
        System.out.println("ContractProfessor.verifyTerm called on employee: " + getId());
    }
    public int getDailyRate() {
        return dailyRate;
    }
    
    public void setDailyRate(int dailyRate) {
        this.dailyRate = dailyRate;
    }
    
    public int getTerm() {
        return term;
    }
    
    public void setTerm(int term) {
        this.term = term;
    }
    public String toString() {
        return "ContractProfessor id: " + getId() + " name: " + getName();
    }
}

File: Professor.java

import java.util.Date;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.DiscriminatorType;
import javax.persistence.Entity;
import javax.persistence.EntityListeners;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.PostLoad;
import javax.persistence.PostPersist;
import javax.persistence.PostUpdate;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
import javax.persistence.Transient;
@Entity
@Table(name="EMP")
@Inheritance(strategy=InheritanceType.JOINED)
@DiscriminatorColumn(name="EMP_TYPE", discriminatorType=DiscriminatorType.INTEGER)
@EntityListeners(ProfessorDebugListener.class)
public abstract class Professor {
    @Id private int id;
    private String name;
    @Temporal(TemporalType.DATE)
    @Column(name="S_DATE")
    private Date startDate;
    @Transient private long syncTime;
    @PostPersist
    @PostUpdate
    @PostLoad 
    private void resetSyncTime() { 
        System.out.println("Professor.resetSyncTime called on employee: " + getId());
        syncTime = System.currentTimeMillis(); 
    }
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    public Date getStartDate() {
        return startDate;
    }
    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName();
    }
}

File: ProfessorDebugListener.java
import javax.persistence.PostPersist;
public class ProfessorDebugListener {
  @PostPersist
  public void auditNewHire(Professor emp) { 
      System.out.println(" called on employee: " + emp.getId());
  }
}

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public Professor createProfessor(int id, String name) {
    Professor emp = new ContractProfessor();
    emp.setId(id);
    emp.setName(name);
    em.persist(emp);
    return emp;
  }
  public void removeProfessor(int id) {
    Professor emp = findProfessor(id);
    if (emp != null) {
      em.remove(emp);
    }
  }
  public Professor changeProfessorName(int id, String newName) {
    Professor emp = findProfessor(id);
    if (emp != null) {
      emp.setName(newName);
    }
    return emp;
  }
  public Professor findProfessor(int id) {
    return em.find(Professor.class, id);
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    service.createProfessor(1, "name");
    for (Professor emp : service.findAllProfessors()) {
      System.out.print(emp);
    }
    service.changeProfessorName(1, "newname");
    for (Professor emp : service.findAllProfessors()) {
      System.out.print(emp);
    }
    service.removeProfessor(1);
    for (Professor emp : service.findAllProfessors()) {
      System.out.print(emp);
    }
    util.checkData("select * from CONTRACT_EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}


File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Many To One Mapping In Mapped Super class

File: BadProfessor.java

import javax.persistence.AssociationOverride;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.JoinColumn;
import javax.persistence.Table;
@Entity
@Table(name="Bad_EMP")
@AssociationOverride(name="manager", 
                     joinColumns=@JoinColumn(name="MGR"))
public class BadProfessor extends CompanyProfessor {
    @Column(name="H_RATE")
    private float hourlyRate;
    public float getHourlyRate() {
        return hourlyRate;
    }
    public void setHourlyRate(float hourlyRate) {
        this.hourlyRate = hourlyRate;
    }
    public String toString() {
        return "PartTimeProfessor id: " + getId() + " name: " + getName();
    }
}

File: CompanyProfessor.java

import javax.persistence.ManyToOne;
import javax.persistence.MappedSuperclass;
@MappedSuperclass
public abstract class CompanyProfessor extends Professor {
    private int vacation;
    @ManyToOne
    private Professor manager;
    public int getVacation() {
        return vacation;
    }
    public void setVacation(int vacation) {
        this.vacation = vacation;
    }
    public Professor getManager() {
        return manager;
    }
    public void setManager(Professor manager) {
        this.manager = manager;
    }
}

File: Professor.java
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity
@Inheritance(strategy=InheritanceType.TABLE_PER_CLASS)
public abstract class Professor  {
    @Id private int id;
    private String name;
    @Temporal(TemporalType.DATE)
    @Column(name="S_DATE")
    private Date startDate;
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    public Date getStartDate() {
        return startDate;
    }
    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName();
    }
}

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public void createProfessor(Professor emp) {
    em.persist(emp);
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    BadProfessor emp2 = new BadProfessor();
    emp2.setId(2);
    emp2.setName("bad");
    
    service.createProfessor(emp2);
    System.out.println("Professors: ");
    for (Professor emp1 : service.findAllProfessors()) {
      System.out.print(emp1);
    }
    util.checkData("select * from BAD_EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}


File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Map Each Class In Hierarchy To Its Own Table

File: BadProfessor.java

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Table;
@Entity
@Table(name="CONTRACT_EMP")
public class BadProfessor extends Professor {
    @Column(name="D_RATE") private int dailyRate;
    private int term;
    
    public int getDailyRate() {
        return dailyRate;
    }
    
    public void setDailyRate(int dailyRate) {
        this.dailyRate = dailyRate;
    }
    
    public int getTerm() {
        return term;
    }
    
    public void setTerm(int term) {
        this.term = term;
    }
    public String toString() {
        return "ContractProfessor id: " + getId() + " name: " + getName();
    }
}

File: Professor.java
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity
@Table(name="EMP")
@Inheritance(strategy=InheritanceType.JOINED)
@DiscriminatorColumn(name="EMP_TYPE")
public abstract class Professor {
    @Id private int id;
    private String name;
    @Temporal(TemporalType.DATE)
    @Column(name="S_DATE")
    private Date startDate;

    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    public Date getStartDate() {
        return startDate;
    }
    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName();
    }
}

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public void createProfessor(Professor emp) {
    em.persist(emp);
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    BadProfessor emp2 = new BadProfessor();
    emp2.setId(2);
    emp2.setName("bad");
    
    service.createProfessor(emp2);
    System.out.println("Professors: ");
    for (Professor emp1 : service.findAllProfessors()) {
      System.out.print(emp1);
    }
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}



File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Map Hierarchical Data

File: Professor.java
import javax.persistence.Basic;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.FetchType;
import javax.persistence.Id;
import javax.persistence.IdClass;
import javax.persistence.JoinColumn;
import javax.persistence.JoinColumns;
import javax.persistence.Lob;
import javax.persistence.ManyToOne;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.SecondaryTable;
import javax.persistence.SecondaryTables;
@Entity
@SecondaryTables( {
    @SecondaryTable(name = "COMPANY", pkJoinColumns = {
        @PrimaryKeyJoinColumn(name = "ID", referencedColumnName = "ID") })
        
})
public class Professor {
  private String country;
  @Id
  private int id;
  private String name;
  @ManyToOne
  @JoinColumns( {
      @JoinColumn(name = "MGR_ID", referencedColumnName = "ID", table = "COMPANY") })
  private Professor manager;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getCountry() {
    return country;
  }
  public void setCountry(String country) {
    this.country = country;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
  public Professor getManager() {
    return manager;
  }
  public void setManager(Professor manager) {
    this.manager = manager;
  }
  public String toString() {
    return "Professor id: " + getId() + " name: " + getName() + " country: " + getCountry();
  }
}

File: ProfessorId.java
import java.io.Serializable;
public class ProfessorId implements Serializable {
  private String country;
  private int id;
  public ProfessorId() {
  }
  public ProfessorId(String country, int id) {
    this.country = country;
    this.id = id;
  }
  public String getCountry() {
    return country;
  }
  public int getId() {
    return id;
  }
  public boolean equals(Object o) {
    return ((o instanceof ProfessorId) && country.equals(((ProfessorId) o).getCountry()) && id == ((ProfessorId) o)
        .getId());
  }
  public int hashCode() {
    return country.hashCode() + id;
  }
}

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public Professor createProfessor(String country, int id, String name) {
    Professor emp = new Professor();
    emp.setCountry(country);
    emp.setId(id);
    emp.setName(name);
    em.persist(emp);
    return emp;
  }
  public Professor findProfessor(String country, int id) {
    return em.find(Professor.class, new ProfessorId(country, id));
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    service.createProfessor("country", 1, "name");
    System.out.println("Professors:");
    for (Professor emp : service.findAllProfessors()) {
      System.out.print(emp);
      System.out.print(emp.getManager());
    }
    util.checkData("select * from Professor");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}


File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Map One POJO To Multiple Tables

File: Professor.java
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.PrimaryKeyJoinColumn;
import javax.persistence.SecondaryTable;
import javax.persistence.Table;
@Entity
@Table(name = "EMP")
@SecondaryTable(name = "EMP_ADDRESS", pkJoinColumns = @PrimaryKeyJoinColumn(name = "EMP_ID"))
public class Professor {
  @Id
  private int id;
  private String name;
  @Column(table = "EMP_ADDRESS")
  private String street;
  @Column(table = "EMP_ADDRESS")
  private String city;
  @Column(table = "EMP_ADDRESS")
  private String state;
  @Column(name = "ZIP_CODE", table = "EMP_ADDRESS")
  private String zip;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
  public String getCity() {
    return city;
  }
  public void setCity(String city) {
    this.city = city;
  }
  public String getState() {
    return state;
  }
  public void setState(String state) {
    this.state = state;
  }
  public String getStreet() {
    return street;
  }
  public void setStreet(String street) {
    this.street = street;
  }
  public String getZip() {
    return zip;
  }
  public void setZip(String zip) {
    this.zip = zip;
  }
  public String toString() {
    return "Professor id: " + getId() + " name: " + getName();
  }
}

File: ProfessorService.java
import java.util.Collection;
import java.util.Date;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public Professor createProfessorAndAddress(int id, String name, 
      String street, String city, String state, String zip) {
  Professor emp = new Professor();
  emp.setId(id);
  emp.setName(name);
  emp.setStreet(street);
  emp.setCity(city);
  emp.setState(state);
  emp.setZip(zip);
  em.persist(emp);
  
  return emp;
}
public Collection<Professor> findAllProfessors() {
  Query query = em.createQuery("SELECT e FROM Professor e");
  return (Collection<Professor>) query.getResultList();
}
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    service.createProfessorAndAddress(1, "name",  "street", "city", "state", "zip");
    System.out.println("Professors and Addresses:");
    for (Professor emp : service.findAllProfessors()) {
      System.out.println(emp);
    }
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}



File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Set Discriminator Column: Discriminator Type INTEGER

File: AbstractProfessor.java

import javax.persistence.MappedSuperclass;
@MappedSuperclass
public abstract class AbstractProfessor extends Professor {
    private int vacation;
    public int getVacation() {
        return vacation;
    }
    public void setVacation(int vacation) {
        this.vacation = vacation;
    }
}

File: BadProfessor.java
import javax.persistence.Column;
import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
import javax.persistence.Table;
@Entity
@Table(name="Bad_EMP")
@DiscriminatorValue("3")
public class BadProfessor extends AbstractProfessor {
    @Column(name="H_RATE")
    private float hourlyRate = 1;
    public float getHourlyRate() {
        return hourlyRate;
    }
    public void setHourlyRate(float hourlyRate) {
        this.hourlyRate = hourlyRate;
    }
    public String toString() {
        return "PartTimeProfessor id: " + getId() + " name: " + getName();
    }
}

File: GoodProfessor.java
import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
import javax.persistence.Table;
@Entity
@Table(name="Good_EMP")
@DiscriminatorValue("2")
public class GoodProfessor extends AbstractProfessor {
    private long salary = 1;
    private long pension = 1;
    
    public long getPension() {
        return pension;
    }
    
    public void setPension(long pension) {
        this.pension = pension;
    }
    
    public long getSalary() {
        return salary;
    }
    
    public void setSalary(long salary) {
        this.salary = salary;
    }
    public String toString() {
        return "FullTimeProfessor id: " + getId() + " name: " + getName();
    }
}

File: Professor.java
import java.util.Date;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.DiscriminatorType;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity
@Table(name = "EMP")
@Inheritance(strategy = InheritanceType.JOINED)
@DiscriminatorColumn(name = "EMP_TYPE", discriminatorType = DiscriminatorType.INTEGER)
public abstract class Professor {
  @Id
  private int id;
  private String name;
  @Temporal(TemporalType.DATE)
  @Column(name = "S_DATE")
  private Date startDate;
  public int getId() {
    return id;
  }
  public void setId(int id) {
    this.id = id;
  }
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
  public Date getStartDate() {
    return startDate;
  }
  public void setStartDate(Date startDate) {
    this.startDate = startDate;
  }
  public String toString() {
    return "Professor id: " + getId() + " name: " + getName();
  }
}

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public void createProfessor(Professor emp) {
    em.persist(emp);
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    GoodProfessor emp = null;
    emp = new GoodProfessor();
    emp.setId(1);
    emp.setName("good");
    
    service.createProfessor(emp);
    
    BadProfessor emp2 = new BadProfessor();
    emp2.setId(2);
    emp2.setName("bad");
    
    service.createProfessor(emp2);
    System.out.println("Professors: ");
    for (Professor emp1 : service.findAllProfessors()) {
      System.out.print(emp1);
    }
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}


File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Set Discriminator Value

File: AbstractProfessor.java

import javax.persistence.MappedSuperclass;
@MappedSuperclass
public abstract class AbstractProfessor extends Professor {
    private int vacation;
    public int getVacation() {
        return vacation;
    }
    public void setVacation(int vacation) {
        this.vacation = vacation;
    }
}

File: BadProfessor.java

import javax.persistence.Column;
import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
@Entity(name="BadEmp")
@DiscriminatorValue("BadEmp")
public class BadProfessor extends AbstractProfessor {
    @Column(name="H_RATE")
    private float hourlyRate;
    public float getHourlyRate() {
        return hourlyRate;
    }
    public void setHourlyRate(float hourlyRate) {
        this.hourlyRate = hourlyRate;
    }
    public String toString() {
        return "PartTimeProfessor id: " + getId() + " name: " + getName();
    }
}

File: GoodProfessor.java

import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
@Entity
@DiscriminatorValue("GoodEmp")
public class GoodProfessor extends AbstractProfessor {
    private long salary;
    private long pension;
    
    public long getPension() {
        return pension;
    }
    
    public void setPension(long pension) {
        this.pension = pension;
    }
    
    public long getSalary() {
        return salary;
    }
    
    public void setSalary(long salary) {
        this.salary = salary;
    }
    public String toString() {
        return "GoodProfessor id: " + getId() + " name: " + getName();
    }
}

File: Professor.java

import java.util.Date;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity 
@Table(name="EMP")
@Inheritance
@DiscriminatorColumn(name="EMP_TYPE")
public abstract class Professor  {
    @Id private int id;
    private String name;
    @Temporal(TemporalType.DATE)
    @Column(name="S_DATE")
    private Date startDate;
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    public Date getStartDate() {
        return startDate;
    }
    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName();
    }
}

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public void createProfessor(Professor emp) {
    em.persist(emp);
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    Professor emp = null;
    emp = new GoodProfessor();
    emp.setId(1);
    emp.setName("good");
    service.createProfessor(emp);
    
    emp = new BadProfessor();
    emp.setId(2);
    emp.setName("bad");
    service.createProfessor(emp);
    System.out.println("Professors: ");
    for (Professor emp1 : service.findAllProfessors()) {
      System.out.print(emp1);
    }
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}


File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Set Inheritance And discriminator Column

File: ContractProfessor.java

import javax.persistence.Column;
import javax.persistence.Entity;
@Entity
public class ContractProfessor extends Professor {
    @Column(name="D_RATE")
    private int dailyRate;
    private int term;
    
    public int getDailyRate() {
        return dailyRate;
    }
    
    public void setDailyRate(int dailyRate) {
        this.dailyRate = dailyRate;
    }
    
    public int getTerm() {
        return term;
    }
    
    public void setTerm(int term) {
        this.term = term;
    }
    public String toString() {
        return "ContractProfessor id: " + getId() + " name: " + getName();
    }
}

File: Professor.java

import java.util.Date;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity 
@Table(name="EMP")
@Inheritance
@DiscriminatorColumn(name="EMP_TYPE")
public abstract class Professor  {
    @Id private int id;
    private String name;
    @Temporal(TemporalType.DATE)
    @Column(name="S_DATE")
    private Date startDate;
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    public Date getStartDate() {
        return startDate;
    }
    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName();
    }
}

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public void createProfessor(Professor emp) {
    em.persist(emp);
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    Professor emp = null;
    emp = new ContractProfessor();
    emp.setId(1);
    emp.setName("name");
    service.createProfessor(emp);
    System.out.println("Professors: ");
    for (Professor emp1 : service.findAllProfessors()) {
      System.out.print(emp1);
    }
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}



File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Single Table Inheritance

File: ContractProfessor.java

import javax.persistence.Column;
import javax.persistence.Entity;
@Entity
public class ContractProfessor extends Professor {
    @Column(name="D_RATE")
    private int dailyRate;
    private int term;
    
    public int getDailyRate() {
        return dailyRate;
    }
    
    public void setDailyRate(int dailyRate) {
        this.dailyRate = dailyRate;
    }
    
    public int getTerm() {
        return term;
    }
    
    public void setTerm(int term) {
        this.term = term;
    }
    public String toString() {
        return "ContractProfessor id: " + getId() + " name: " + getName();
    }
}

File: Professor.java

import java.util.Date;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity 
@Table(name="EMP")
@Inheritance
@DiscriminatorColumn(name="EMP_TYPE")
public abstract class Professor  {
    @Id private int id;
    private String name;
    @Temporal(TemporalType.DATE)
    @Column(name="S_DATE")
    private Date startDate;
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    public Date getStartDate() {
        return startDate;
    }
    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName();
    }
}

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public void createProfessor(Professor emp) {
    em.persist(emp);
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    Professor emp = null;
    emp = new ContractProfessor();
    emp.setId(1);
    emp.setName("name");
    service.createProfessor(emp);
    System.out.println("Professors: ");
    for (Professor emp1 : service.findAllProfessors()) {
      System.out.print(emp1);
    }
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}


File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Using Mapped Super class

File: Professor.java

import java.util.Date;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.Table;
import javax.persistence.Temporal;
import javax.persistence.TemporalType;
@Entity 
@Table(name="EMP")
@Inheritance
@DiscriminatorColumn(name="EMP_TYPE")
public abstract class Professor  {
    @Id private int id;
    private String name;
    @Temporal(TemporalType.DATE)
    @Column(name="S_DATE")
    private Date startDate;
    public int getId() {
        return id;
    }
    
    public void setId(int id) {
        this.id = id;
    }
    
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    public Date getStartDate() {
        return startDate;
    }
    public void setStartDate(Date startDate) {
        this.startDate = startDate;
    }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName();
    }
}

File: BadProfessor.java

import javax.persistence.Column;
import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
@Entity(name="BadEmp")
@DiscriminatorValue("BadEmp")
public class BadProfessor extends AbstractProfessor {
    @Column(name="H_RATE")
    private float hourlyRate;
    public float getHourlyRate() {
        return hourlyRate;
    }
    public void setHourlyRate(float hourlyRate) {
        this.hourlyRate = hourlyRate;
    }
    public String toString() {
        return "PartTimeProfessor id: " + getId() + " name: " + getName();
    }
}

File: GoodProfessor.java

import javax.persistence.DiscriminatorValue;
import javax.persistence.Entity;
@Entity
@DiscriminatorValue("GoodEmp")
public class GoodProfessor extends AbstractProfessor {
    private long salary;
    private long pension;
    
    public long getPension() {
        return pension;
    }
    
    public void setPension(long pension) {
        this.pension = pension;
    }
    
    public long getSalary() {
        return salary;
    }
    
    public void setSalary(long salary) {
        this.salary = salary;
    }
    public String toString() {
        return "GoodProfessor id: " + getId() + " name: " + getName();
    }
}

File: ProfessorService.java
import java.util.Collection;
import javax.persistence.EntityManager;
import javax.persistence.Query;
public class ProfessorService {
  protected EntityManager em;
  public ProfessorService(EntityManager em) {
    this.em = em;
  }
  public void createProfessor(Professor emp) {
    em.persist(emp);
  }
  public Collection<Professor> findAllProfessors() {
    Query query = em.createQuery("SELECT e FROM Professor e");
    return (Collection<Professor>) query.getResultList();
  }
}

File: AbstractProfessor.java

import javax.persistence.MappedSuperclass;
@MappedSuperclass
public abstract class AbstractProfessor extends Professor {
    private int vacation;
    public int getVacation() {
        return vacation;
    }
    public void setVacation(int vacation) {
        this.vacation = vacation;
    }
}

File: JPAUtil.java
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;
public class JPAUtil {
  Statement st;
  
  public JPAUtil() throws Exception{
    Class.forName("org.hsqldb.jdbcDriver");
    System.out.println("Driver Loaded.");
    String url = "jdbc:hsqldb:data/tutorial";
    Connection conn = DriverManager.getConnection(url, "sa", "");
    System.out.println("Got Connection.");
    st = conn.createStatement();
  }
  public void executeSQLCommand(String sql) throws Exception {
    st.executeUpdate(sql);
  }
  public void checkData(String sql) throws Exception {
    ResultSet rs = st.executeQuery(sql);
    ResultSetMetaData metadata = rs.getMetaData();
    for (int i = 0; i < metadata.getColumnCount(); i++) {
      System.out.print("\t"+ metadata.getColumnLabel(i + 1)); 
    }
    System.out.println("\n----------------------------------");
    while (rs.next()) {
      for (int i = 0; i < metadata.getColumnCount(); i++) {
        Object value = rs.getObject(i + 1);
        if (value == null) {
          System.out.print("\t       ");
        } else {
          System.out.print("\t"+value.toString().trim());
        }
      }
      System.out.println("");
    }
  }
}

File: Main.java
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
public class Main {
  public static void main(String[] a) throws Exception {
    JPAUtil util = new JPAUtil();
    EntityManagerFactory emf = Persistence.createEntityManagerFactory("ProfessorService");
    EntityManager em = emf.createEntityManager();
    ProfessorService service = new ProfessorService(em);
    em.getTransaction().begin();
    Professor emp = null;
    emp = new GoodProfessor();
    emp.setId(1);
    emp.setName("good");
    service.createProfessor(emp);
    
    emp = new BadProfessor();
    emp.setId(2);
    emp.setName("bad");
    service.createProfessor(emp);
    System.out.println("Professors: ");
    for (Professor emp1 : service.findAllProfessors()) {
      System.out.print(emp1);
    }
    util.checkData("select * from EMP");
    em.getTransaction().rumit();
    em.close();
    emf.close();
  }
}


File: persistence.xml
<persistence xmlns="http://java.sun.ru/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.ru/xml/ns/persistence http://java.sun.ru/xml/ns/persistence/persistence" version="1.0">
  <persistence-unit name="JPAService" transaction-type="RESOURCE_LOCAL">
    <properties>
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect"/>
      <property name="hibernate.hbm2ddl.auto" value="update"/>
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver"/>
      <property name="hibernate.connection.username" value="sa"/>
      <property name="hibernate.connection.password" value=""/>
      <property name="hibernate.connection.url" value="jdbc:hsqldb:data/tutorial"/>
    </properties>
  </persistence-unit>
</persistence>

Java/JPA/Inheritance — различия между версиями

Текущая версия на 07:22, 1 июня 2010

Содержание

Change Inheritance Type In Hierarchy

Inheritance Type JOINED

Inheritance Type TABLE_PER_CLASS

Lifecycle CallBack: Add Listener To Subclass

Lifecycle CallBack Exclude Superclass Listeners

Many To One Mapping In Mapped Super class

Map Each Class In Hierarchy To Its Own Table

Map Hierarchical Data

Map One POJO To Multiple Tables

Set Discriminator Column: Discriminator Type INTEGER

Set Discriminator Value

Set Inheritance And discriminator Column

Single Table Inheritance

Using Mapped Super class

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Версия 18:01, 31 мая 2010 (просмотреть исходный код) (обсуждение)	Текущая версия на 07:22, 1 июня 2010 (просмотреть исходный код) Admin (обсуждение \| вклад) м (1 версия)
(нет различий)