A component is a contained object which is persisted as a value, not as an entity.
To implement the same we need to use <component> element in the mapping file.
And will have one single table to keep the value of varaiables of contained object.
Example:
Suppose we have one table: Employee with columns-id,fname,lname,age,sex.
And we will have one entity with name Employee and another with name as Name.
package com.javasafari;
public class Name {
private String fname,lname;
//getters and setters
}
package com.javasafari;
public class Employee {
private int id;
private Name name;
private int age;
private String sex;
//getters and setters
}
Here name is a dependent contained object.
Mapping file will look like:
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD//EN"
"http://www.hibernate.org/dtd/hibernate-mapping-3.0.dtd">
<hibernate-mapping>
<class name="Employee" table="EMPLOYEE">
<id name="id" type="int" column="id">
<generator class="native"/>
</id>
<component name="name" class="Name">
<property name="fname" column="first_name" type="string"/>
<property name="lname" column="last_name" type="string"/>
</component>
<property name="age" column="age" type="int"/>
<property name="sex" column="sex" type="string"/>
</class>
</hibernate-mapping>
To save as Employee object:
Session s=new Configuration().configure("hibernate.cfg.xml")
.buildSessionFactory().openSession();
Transaction t=s.beginTransaction();
t.begin();
Employee e1=new Employee(new Name("Ankit","Adlakha"),26,Male);
s.save(e1);
t.commit();
s.close();