HB: Hibernate One-To-Many Using Annotation:

Hibernate One-To-Many Using Annotation:
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Files required are :

Employee.java
Address.java
hibernate.cfg.xml
SaveData.java

I am defining one parent (Employee.java) and one child class (Address.java).
Logic : Define one of the Collections i.e. Set in parent class , child objects needs to be added to this Set, associated with Employee, persist Employee object and commit the data.

Employee.java
===========

package mypackage;

import java.util.Set;
import javax.persistence.CascadeType;
import javax.persistence.Column;
import javax.persistence.Entity;
import javax.persistence.Id;
import javax.persistence.JoinColumn;
import javax.persistence.OneToMany;
import javax.persistence.Table;
@Entity
@Table(name = "EMPLOYEE")
public class Employee {
    @Id
    @Column(name = "empid")
    private int empId;
    @Column(name = "empName")
    private String empName;
    @OneToMany(targetEntity = Address.class,cascade = CascadeType.ALL)
    @JoinColumn(name = "empId_fk" , referencedColumnName = "empid")
// empId_fk is foreign key for empid defined in Employee class.
    private Set address;

    public int getEmpId() {
        return empId;
    }

    public void setEmpId(int empId) {
        this.empId = empId;
    }

    public String getEmpName() {
        return empName;
    }

    public void setEmpName(String empName) {
        this.empName = empName;
    }

    public Set getAddress() {
        return address;
    }

    public void setAddress(Set address) {
        this.address = address;
    }

}

Address.java

==========

package mypackage;

import javax.persistence.Column;

import javax.persistence.Entity;

import javax.persistence.Id;

import javax.persistence.Table;

@Entity

@Table(name = "ADDRESS")

public class Address {

    @Id

    @Column(name = "addrId")

    private int addrId;

    @Column(name = "addrName")

    private String addrName;

    public int getAddrId() {

        return addrId;

    }

    public void setAddrId(int addrId) {

        this.addrId = addrId;

    }

    public String getAddrName() {

        return addrName;

    }

    public void setAddrName(String addrName) {

        this.addrName = addrName;

    }

    

    

}

hibernate,cfg,xml

=============

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN" "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">

<hibernate-configuration>

  <session-factory>

    <property name="hibernate.dialect">org.hibernate.dialect.DerbyDialect</property>

    <property name="hibernate.connection.driver_class">org.apache.derby.jdbc.ClientDriver</property>

    <property name="hibernate.connection.url">jdbc:derby://localhost:1527/technology</property>

    <property name="hibernate.connection.username">app</property>

    <property name="hibernate.connection.password">app</property>

    <property name="show_sql">true</property>

    <property name="hbm2ddl.auto">create</property>

    <mapping class="mypackage.Address" />

    <mapping class="mypackage.Employee" />

  </session-factory>

</hibernate-configuration>

SaveData.java
===========

package mypackage;

import java.util.HashSet;

import java.util.Set;

import org.hibernate.cfg.*;

import org.hibernate.*;

public class SaveData {

       

    public static void main(String[] args){

    SessionFactory factory = new Configuration().configure().buildSessionFactory();

     Session session = factory.openSession();

    Transaction tx = session.beginTransaction();

    Employee emp = new Employee();

    Address addr1 = new Address();

    Address addr2 = new Address();

    addr1.setAddrId(11111);

    addr1.setAddrName("Mohan1111");

    addr2.setAddrId(33333);

    addr2.setAddrName("Mohan3333");

    emp.setEmpId(22222);

    emp.setEmpName("Bengaluru");

    Set set = new HashSet();

    set.add(addr1);

    set.add(addr2);

    emp.setAddress(set);

    session.save(emp);

    tx.commit();

    session.close();        

    factory.close();

    System.out.println("Saved the data successfully...");

    

    }

    

}