Java by API/javax.persistence/Column — различия между версиями

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м (1 версия)
 
м (1 версия)
 
(нет различий)

Текущая версия на 14:34, 31 мая 2010

Column: columnDefinition()

  

File: Professor.java
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Professor {
  @Id
  @Column(columnDefinition = "VARCHAR(40)")
  private String name;
  @Column(name = "START_DATE", columnDefinition = "DATE DEFAULT CURRENT_DATE")
  private java.sql.Date startDate;
  public String getName() {
    return name;
  }
  public void setName(String name) {
    this.name = name;
  }
  public java.sql.Date getStartDate() {
    return startDate;
  }
  public void setStartDate(java.sql.Date startDate) {
    this.startDate = startDate;
  }
}

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 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.findAllProfessors();
    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>





Column.length()

  

File: Professor.java

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.ManyToOne;
@Entity
public class Professor {
    @Id 
    @Column(length=40) 
    private String name;
    @ManyToOne 
    @JoinColumn(name="MGR")
    private Professor manager;
    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;
    }
}

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 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.findAllProfessors();
    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>





Column.name()

  

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>





Column.nullable()

  

File: Professor.java
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Professor {
    @Id private int id;
    
    @Column(unique=true, nullable=false) 
    private String name;
    private long salary;
    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 long getSalary() {
        return salary;
    }
    
    public void setSalary(long salary) {
        this.salary = salary;
    }
    
    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 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.findAllProfessors();
    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>





Column.precision()

  

File: Professor.java

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Professor {
    @Id 
    @Column(length=40) 
    private String name;
    @Column(precision=8, scale=2) 
    private float hourlyRate;
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    public float getHourlyRate() {
      return hourlyRate;
    }
    public void setHourlyRate(float hourlyRate) {
      this.hourlyRate = hourlyRate;
    }

}

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 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.findAllProfessors();
    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>





Column.scale()

  

File: Professor.java

import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Professor {
    @Id 
    @Column(length=40) 
    private String name;
    @Column(precision=8, scale=2) 
    private float hourlyRate;
    public String getName() {
        return name;
    }
    
    public void setName(String name) {
        this.name = name;
    }
    public float getHourlyRate() {
      return hourlyRate;
    }
    public void setHourlyRate(float hourlyRate) {
      this.hourlyRate = hourlyRate;
    }

}

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 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.findAllProfessors();
    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>





Column.table()

  

File: Address.java

import javax.persistence.Column;
import javax.persistence.Embeddable;
@Embeddable
public class Address {
    private String street; 
    private String city; 
    private String state;
    @Column(name="ZIP_CODE")
    private String zip;
    public String getStreet() {
        return street;
    }
    
    public void setStreet(String address) {
        this.street = address;
    }
    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 getZip() {
        return zip;
    }
    public void setZip(String zip) {
        this.zip = zip;
    }
    public String toString() {
        return "Address street: " + getStreet() +
               ", city: " + getCity() +
               ", state: " + getState() +
               ", zip: " + getZip();
    }
}

File: Professor.java

import javax.persistence.AttributeOverride;
import javax.persistence.AttributeOverrides;
import javax.persistence.Column;
import javax.persistence.Embedded;
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;
    @Embedded
    @AttributeOverrides({
        @AttributeOverride(name="street", column=@Column(table="EMP_ADDRESS")),
        @AttributeOverride(name="city", column=@Column(name="CITY", table="EMP_ADDRESS")),
        @AttributeOverride(name="state", column=@Column(name="STATE", table="EMP_ADDRESS")),
        @AttributeOverride(name="zip",
                           column=@Column(name="ZIP_CODE", table="EMP_ADDRESS"))
    })
    private Address address;

    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 Address getAddress() {
        return address;
    }
    
    public void setAddress(Address address) {
        this.address = address; 
    }
    public String toString() {
        return "Professor id: " + getId() + " name: " + getName() +
               " with " + getAddress();
    }
}

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);
    Address addr = new Address();
    addr.setStreet(street);
    addr.setCity(city);
    addr.setState(state);
    addr.setZip(zip);
    emp.setAddress(addr);
    em.persist(emp);
    return 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();
    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: 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>





Column.unique()

  
File: Professor.java
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
@Entity
public class Professor {
    @Id private int id;
    
    @Column(unique=true, nullable=false) 
    private String name;
    private long salary;
    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 long getSalary() {
        return salary;
    }
    
    public void setSalary(long salary) {
        this.salary = salary;
    }
    
    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 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.findAllProfessors();
    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>


Источник — «http://jexp.ru/index.php?title=Java_by_API/javax.persistence/Column&oldid=1651»