Attribute Overrides For Embeddable ID : Attribute Overrides « JPA « Java Tutorial

1. Java Tutorial
2. JPA
3. Attribute Overrides

File: Employee.java

import javax.persistence.AttributeOverride;
import javax.persistence.AttributeOverrides;
import javax.persistence.Column;
import javax.persistence.EmbeddedId;
import javax.persistence.Entity;
import javax.persistence.Transient;

@Entity
public class Employee implements java.io.Serializable {
  private String firstName;

  private EmployeePK pk;

  public String getFirstName() {
    return firstName;
  }

  public void setFirstName(String firstName) {
    this.firstName = firstName;
  }

  @EmbeddedId
  @AttributeOverrides( {
      @AttributeOverride(name = "lastName", column = @Column(name = "LAST_NAME")),
      @AttributeOverride(name = "ssn", column = @Column(name = "SSN")) })
  public EmployeePK getPk() {
    return pk;
  }

  public void setPk(EmployeePK pk) {
    this.pk = pk;
  }

  @Transient
  public String getLastName() {
    return pk.getLastName();
  }

  @Transient
  public long getSsn() {
    return pk.getSsn();
  }
}

File: EmployeePK.java

import javax.persistence.Column;
import javax.persistence.Embeddable;

@Embeddable
public class EmployeePK implements java.io.Serializable {
  private String lastName;

  private long ssn;

  public EmployeePK() {
  }

  public EmployeePK(String lastName, long ssn) {
    this.lastName = lastName;
    this.ssn = ssn;
  }

  @Column(name = "CUSTOMER_LAST_NAME")
  public String getLastName() {
    return this.lastName;
  }

  public void setLastName(String lastName) {
    this.lastName = lastName;
  }

  @Column(name = "CUSTOMER_SSN")
  public long getSsn() {
    return ssn;
  }

  public void setSsn(long ssn) {
    this.ssn = ssn;
  }

  public boolean equals(Object obj) {
    if (obj == this)
      return true;
    if (!(obj instanceof EmployeePK))
      return false;
    EmployeePK pk = (EmployeePK) obj;
    if (!lastName.equals(pk.lastName))
      return false;
    if (ssn != pk.ssn)
      return false;
    return true;
  }

  public int hashCode() {
    return lastName.hashCode() + (int) ssn;
  }
}

File: Helper.java

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.Statement;

public class Helper {
  public static void checkData() throws Exception {
    Class.forName("org.hsqldb.jdbcDriver");
    Connection conn = DriverManager.getConnection("jdbc:hsqldb:data/tutorial", "sa", "");
    Statement st = conn.createStatement();

    ResultSet mrs = conn.getMetaData().getTables(null, null, null, new String[] { "TABLE" });
    while (mrs.next()) {
      String tableName = mrs.getString(3);
      System.out.println("\n\n\n\nTable Name: "+ tableName);

      ResultSet rs = st.executeQuery("select * from " + tableName);
      ResultSetMetaData metadata = rs.getMetaData();
      while (rs.next()) {
        System.out.println(" Row:");
        for (int i = 0; i < metadata.getColumnCount(); i++) {
          System.out.println("    Column Name: "+ metadata.getColumnLabel(i + 1)+ ",  ");
          System.out.println("    Column Type: "+ metadata.getColumnTypeName(i + 1)+ ":  ");
          Object value = rs.getObject(i + 1);
          System.out.println("    Column Value: "+value+"\n");
        }
      }
    }
  }
}

File: Main.java

import java.util.List;

import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import javax.persistence.Query;

public class Main {
  static EntityManagerFactory emf = Persistence.createEntityManagerFactory("JPAService");

  static EntityManager em = emf.createEntityManager();

  public static void main(String[] a) throws Exception {
    em.getTransaction().begin();




    em.getTransaction().commit();
    em.close();
    emf.close();

    Helper.checkData();
  }
}

File: persistence.xml

<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/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>

22.31.Attribute Overrides
	22.31.1.	Using Attribute Overrides
	22.31.2.	Attribute Overrides For Secondary Table
	22.31.3.	Attribute Overrides For Embeddable ID
	22.31.4.	Subclass With Attribute Overrides