Hibernate Criteria, Hibernate filter, Hibernate Example, Hibernate Criteria and Filter Example

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Hibernate Query and Hibernate Criteria demo with example code
By just extending an example that was already on display in this site,
I just tried to add some Hibernate Filter and Hibernate Criteria 
features provided by Hibernate Framework.

Software environment that I have used in this example are as follows:
1. Eclipse 3.2
2. JDK 1.5
3. Hibernate 3.2

And I tried to see ways of using two ways of putting where condition to
any SQL that is ultimately executed at database side.

In order to use Hibernate Filter functionality, one has to define
the Filter in HBM descriptor XML file, within <filter-def> Tag.
This Filter-def tag can be defined at the class Tag level or within the
dependent or related SET/BAG collection tag (in case of one to many
type of mapping). So the existing DeptsEmployee.HBM.XML file will 
be having entries for Filter-Def, Filter-Param and Filter Tags, as 
follows:











DeptsEmployee.HBM.XML
 <?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">
<hibernate-mapping package="demo">
  <class name="Dept" table="dept">
    <id name="deptId" column="dept_id">
      <generator class="assigned"/>
    </id>
    <property name="deptName" column="dept_name" type="java.lang.String"/>
    <set name="employees" table="employee" cascade="persist,delete">
      <key column="dept_id" />
      <one-to-many class="Employee"/>
    </set>
  </class>
  <class name="Employee" table="employee">
    <id name="employeeId" column="employee_id">
      <generator class="assigned"/>
    </id>
    <property name="employeeName" column="employee_name" type="java.lang.String"/>
    <one-to-one name="dept" class="Dept" />
    <filter name="listStartsWithCapitalT" condition="employee_name like :employeeName1"/>
  </class>
  <filter-def name="listStartsWithCapitalT">
	  <filter-param name="employeeName1" type="string"/>
  </filter-def>

</hibernate-mapping>


Remaining files of this example can be used from the following link,
http://www.techienjoy.com/Hibernate-One-to-Many-mapping-example.php
as I have just used files from that Page for rapidly setting up
environment for one to Many Hibernate mapping example with Hibernate Filter
and Hibernate Criteria and Hibernate Query.
List of files includes:
Dept.java
Employee.java
hibernate.cfg.xml

As the above HBM XML file shows, filter-def has a filter-param with a name and
type attribute. This filter-def name attribute will be used in filter Tag in 
the class or set tags etc. Tag filter-param name attribute will be used 
with a ":" prefix, as the place holder in the where criteria expression,
whose value is to be passed from the Client code.

    <filter name="listStartsWithCapitalT" condition="employee_name like :employeeName1"/>


Now we can go through the Client code, showing ways to use Hibernate Filter
with Hibernate criteria. Before using any Hibernate Filter, it has to be
enabled for the Hibernate Session that is to be used for executing the 
Query or Criteria.


Client.java
 
/**
*  This source is provided as is, without any warranty
*  and /or guaranty of any kind.
*  Copyright (C) 2008, TECHIENJOY.COM, All Rights Reserved.
*  You can use it for Personal Learning purpose only.
*  E-mail: usingframeworks @ gmail . com
*/
package demo;

import java.util.HashSet;
import java.util.List;
import java.util.Set;

import org.hibernate.Criteria;
import org.hibernate.Session;
import org.hibernate.SessionFactory;
import org.hibernate.Transaction;
import org.hibernate.cfg.Configuration;
import org.hibernate.criterion.Restrictions;

public class Client {
    // Hibernate SessionFactory
    SessionFactory sessionFactory;
    public Client() {
        //Hibernate Configuration
        Configuration conf = new Configuration();
        //Loading configuration properties file 
		//and building Hibernate SessionFactory.
        sessionFactory =
		    conf.configure("hibernate.cfg.xml")
			    .buildSessionFactory();
        if(sessionFactory != null) {
            Session session = sessionFactory.getCurrentSession();
            Transaction trans = session.getTransaction();
            trans.begin();
            session.enableFilter("listStartsWithCapitalT");
            Criteria criteria = session.createCriteria(Employee.class);
            session.getEnabledFilter("listStartsWithCapitalT")
			       .setParameter("employeeName1", "%test%");
            criteria.add(Restrictions.like("employeeName", "%test1"));
            List list = criteria.list();
            System.out.println(list.size());
            trans.commit();         
        }
        
    }
	
    /**
     * Client main method
     * @param args
     */
    public static void main(String[] args) {
        new Client(); 
    }

}


As shown in the above Client code, we have used both Filter and 
Hibernate Criteria with Restrictions to add another filter criteria
So following is the final SQL that is getting printed in screen output
/ console as

 (Auto generated by Hibernate, just for reference)
select this_.employee_id as employee1_1_1_, this_.employee_name as
employee2_1_1_, dept2_.dept_id as dept1_0_0_, dept2_.dept_name as dept2_0_0_
from employee this_ left outer join dept dept2_ on
this_.employee_id=dept2_.dept_id where this_.employee_name like ? and
this_.employee_name like ?



As the section in bold (above) shows that we have enabled the filter criteria
as defined in HBM file, as well as the Client code using Hibernate 
Restrictions feature to add LIKE function for the employee name
like filter criteria.


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