Join Example using one to many in hibernate

Step1st:-  Create POJO Class for Vendor and Customer:-
package scs;
import java.util.Set;
public class Vendor {
   private int vid;
   private String vname;
   private Set children;
 
public Set getChildren() {
return children;
}
public void setChildren(Set children) {
this.children = children;
}
public int getVid() {
return vid;
}
public void setVid(int vid) {
this.vid = vid;
}
public String getVname() {
return vname;
}
public void setVname(String vname) {
this.vname = vname;
}  
}

package scs;

public class Customer {

  private int customerid;

  private String customername;

  private int fid;

public int getCustomerid() {

return customerid;

}

public void setCustomerid(int customerid) {

this.customerid = customerid;

}

public String getCustomername() {

return customername;

}

public void setCustomername(String customername) {

this.customername = customername;

}

public int getFid() {

return fid;

}

public void setFid(int fid) {

this.fid = fid;

}

   }

Step2nd:-  Create hbm.xml file for vendor and customer

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

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

<class name="scs.Vendor" table="tbl_vendor">

<id name="vid" >

<generator class="assigned"></generator>

</id>

<property name="vname" />

<set name="children" cascade="all" >

<key column="fid"></key>

<one-to-many class="scs.Customer" />

</set>

</class>

</hibernate-mapping>

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

<!DOCTYPE hibernate-mapping PUBLIC

"-//Hibernate/Hibernate Mapping DTD 3.0//EN"

"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping>

<class name="scs.Customer" table="tbl_customer">

<id name="customerid" >

<generator class="assigned"></generator>

</id>

<property name="customername" />

</class>

</hibernate-mapping>

Step3rd:-  add hbm file in cfg.xml file 

<?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="connection.driver_class">com.mysql.jdbc.Driver</property>

<property name="connection.url">jdbc:mysql://localhost:3306/hdb1</property>

<property name="connection.username">root</property>

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

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

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

<mapping resource="vendor.hbm.xml"></mapping>

<mapping resource="customer.hbm.xml"></mapping>

 <!--  <mapping resource="hibernate.hbm.xml"></mapping>

 <mapping resource="admin.hbm.xml"></mapping>-->

</session-factory>

</hibernate-configuration>

Step4th:-

Add Record in vendor and customer object for database insertion:

package scs;

import java.util.HashSet;

import java.util.Set;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.Transaction;

import org.hibernate.cfg.Configuration;

public class MappingExample {

  public static void main(String args[])

  {

    Configuration cfg = new Configuration();

cfg.configure("hibernate.cfg.xml");

SessionFactory sf = cfg.buildSessionFactory();

Session s = sf.openSession();

Customer c1 = new Customer();

c1.setCustomerid(1001);

c1.setCustomername("abc");

Customer c2 = new Customer();

c2.setCustomerid(1002);

c2.setCustomername("mno");

Vendor v = new Vendor();

v.setVid(1);

v.setVname("v101");

Set st = new HashSet<Customer>();

st.add(c1);

st.add(c2);

v.setChildren(st);

Transaction tx = s.beginTransaction();

s.save(v);

tx.commit();

s.close();

  }

}

Step 5th:-  Apply join (inner,left,right,full )

package scs;

import org.hibernate.Query;

import org.hibernate.Session;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.Configuration;

import java.util.*;

public class JoinExample {

public static void main(String[] args) {

Configuration cfg = new Configuration();

cfg.configure("hibernate.cfg.xml");

SessionFactory sf = cfg.buildSessionFactory();

Session s = sf.openSession();

Query q = s.createQuery("select v.vid ,v.vname ,c.customername from Vendor v inner join v.children c");

List lst = q.list();

Iterator it = lst.iterator();

while(it.hasNext())

{

Object arr[] = (Object[])it.next();

System.out.println(arr[0] +" "+arr[1]);

}

}

}