Java by API/javax.persistence/PrimaryKeyJoinColumn

PrimaryKeyJoinColumn: name()

   <source lang="java">
 

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>

 </source>
   
  
 
  

PrimaryKeyJoinColumn: referencedColumnName()

   <source lang="java">
 

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>

 </source>