Abstract Class As Mapped Superclass : Inheritance « JPA « Java Tutorial






File: Customer.java

import java.io.Serializable;

import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.DiscriminatorColumn;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.Id;
import javax.persistence.Inheritance;
import javax.persistence.InheritanceType;
import javax.persistence.JoinColumn;
import javax.persistence.MappedSuperclass;
import javax.persistence.OneToOne;
import javax.persistence.Table;
import javax.persistence.Version;

@Entity
@Table(name = "ADDRESS")
class Address implements Serializable {
  protected String city;

  @Id
  protected Long id;



  @Version
  protected Long version;

  @Column(name = "ZIP_CODE")
  protected Long zipCode;

  public Address() {
  }

  public String getCity() {
    return city;
  }

  public void setCity(String city) {
    this.city = city;
  }

  public void setId(Long id) {
    this.id = id;
  }

  public Long getId() {
    return id;
  }
  public Long getZipCode() {
    return zipCode;
  }

  public void setZipCode(Long zipCode) {
    this.zipCode = zipCode;
  }
}

@Entity
@Inheritance(strategy = InheritanceType.JOINED)
@DiscriminatorColumn(name = "TYPE")
class Employee extends Person implements Serializable {
  protected String email;

  protected String dept;

  public Employee() {
  }

  public String getEmail() {
    return email;
  }

  public void setEmail(String email) {
    this.email = email;
  }

  public String getDept() {
    return dept;
  }

  public void setDept(String dept) {
    this.dept = dept;
  }
}

@MappedSuperclass
abstract class Person implements Serializable {


  @OneToOne(cascade = { CascadeType.ALL })
  @JoinColumn(name = "HOME_ADDRESS", referencedColumnName = "ID")
  private Address homeAddress;

  @Id
  @Column(nullable = false)
  @GeneratedValue(generator = "PersonIdGenerator")
  private Long id;


  @Version
  private Long version;

  public Person() {
  }
  public Address getHomeAddress() {
    return homeAddress;
  }

  public void setHomeAddress(Address homeAddress) {
    this.homeAddress = homeAddress;
  }

  public Long getId() {
    return id;
  }

  public void setId(Long id) {
    this.id = id;
  }

}

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();


    Customer cus = new Customer();
    
    cus.setFirstName("asdf");
    
    em.persist(cus);

    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>
  Download:  JPA-abstractClassAsMappedSuperclass.zip( 5,288 k)








22.16.Inheritance
22.16.1.Persist subclass
22.16.2.Three Leve Entity Hierarchy
22.16.3.Set Discriminator Value In Subclass
22.16.4.Mark Discriminator Column For Entities In Hierarchy
22.16.5.Mark Abstract Entity With Inheritance
22.16.6.Inheritance Type TABLE_PER_CLASS
22.16.7.Inheritance Type JOINED
22.16.8.Discriminator Type: INTEGER
22.16.9.Discriminator Column And Discriminator Value
22.16.10.Change Inheritance Type
22.16.11.Add Properties In Abstract Entity
22.16.12.Adding Properties To SubClasses
22.16.13.Abstract Class As Mapped Superclass