Developing Struts Hibernate Plugin

In this section we will develop java code for Struts Hibernate Plugin. Our Hibernate Plugin will create Hibernate Session factory and cache it in the servlet context. This strategy enhances the performance of the application.

Source Code Of Hibernate Struts Plugin:


package roseindia.net.plugin;



import java.net.URL;

import javax.servlet.ServletContext;

import javax.servlet.ServletException;

import org.hibernate.SessionFactory;

import org.hibernate.cfg.Configuration;

import org.apache.commons.logging.Log;

import org.apache.commons.logging.LogFactory;

import org.apache.struts.action.ActionServlet;

import org.apache.struts.action.PlugIn;

import org.apache.struts.config.ModuleConfig;

import org.hibernate.HibernateException;





public class HibernatePlugIn implements PlugIn {

   private String _configFilePath = "/hibernate.cfg.xml";



    /**

     * the key under which the <code>SessionFactory
</code> instance is stored

     * in the <code>ServletContext</code>.

     */

    public static final String SESSION_FACTORY_KEY = SessionFactory.class.getName();



  private SessionFactory _factory = null;



   public void destroy() {

     try{

       _factory.close();

     }catch(HibernateException e){

      System.out.println("Unable to close Hibernate Session Factory: " + e.getMessage());

     }

       

   }



   public void init(ActionServlet servlet, 

ModuleConfig config) throws ServletException {

     System.out.println("*************************************");

   System.out.println("**** Initilizing HibernatePlugIn   **********");

        Configuration configuration = null;

        URL configFileURL = null;

        ServletContext context = null;



   try{

            configFileURL = 

HibernatePlugIn.class.getResource(_configFilePath);

            context = servlet.getServletContext();

            configuration =
(new Configuration()).configure(configFileURL);

            _factory = configuration.buildSessionFactory();

      //Set the factory into session

      context.setAttribute(SESSION_FACTORY_KEY, _factory);



   }catch(HibernateException e){

    System.out.println("Error while initializing hibernate: " + e.getMessage());

   }

   System.out.println("**************** *********************");



   }



    /**

     * Setter for property configFilePath.

     * @param configFilePath New value of property configFilePath.

     */

    public void setConfigFilePath(String configFilePath) {

        if ((configFilePath == null) || (configFilePath.trim().length() == 0)) {

            throw new IllegalArgumentException("configFilePath cannot be blank or null.");

        }

        

        System.out.println("Setting '
configFilePath' to '"  + configFilePath + "'...");

        _configFilePath = configFilePath;

    }





/*(SessionFactory) servletContext.getAttribute

(HibernatePlugIn.SESSION_FACTORY_KEY);

*/

  

}

In our plugin class we have define a variable _configFilePath to hold the name of Hibernate Configuration file.

private String _configFilePath = "/hibernate.cfg.xml";

Following code define the key to store the session factory instance in the Servlet context.

public static final String SESSION_FACTORY_KEY = SessionFactory.class.getName();

The init() is called on the startup of the Struts Application. On startup the session factory is initialized and cached in the Servlet context.

configFileURL = HibernatePlugIn.class.getResource(_configFilePath);
context = servlet.getServletContext();
configuration = (new Configuration()).configure(configFileURL);
_factory = configuration.buildSessionFactory();
//Set the factory into session
context.setAttribute(SESSION_FACTORY_KEY, _factory);

Changes to be done in struts-config.xml file

Configuring Hibernate with Struts is very simple work it requires you to have hibernate.cfg.xml in your WEB-INF/classes directory, and to add the following line to the struts-config.xml file.

<plug-in className="roseindia.net.plugin.HibernatePlugIn"></plug-in>

Testing the Plugin

Build your application and deploy on the tomcat server. Start tomcat server and observe the console output. It should display the following line:

log4j:WARN Please initialize the log4j system properly.
*************************************
**** Initilizing HibernatePlugIn **********
*************************************
Aug 7, 2006 10:09:53 AM org.apache.struts.tiles.TilesPlugin initD

This means you have successfully configured your Struts Hibernate Plugin with struts application.

Current Comments

11 comments so far (post your own) View All Comments Latest 10 Comments:

Hi,

This was really a very nice article.

Cheers,

Ujjwal B Soni

Posted by ujjwal sioni on Monday, 11.17.08 @ 00:18am | #81732

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is it necessary to use pulgin to integrate struts and hibernate

Posted by kk on Thursday, 09.18.08 @ 16:20pm | #80304

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I am writing a struts-hibernate plugin. I wrote a plugin for hibernate and inserted the plugin tag in struts-config.xml. I am getting the error " The requested resource (/strutshibernate) is not available." If I don't insert the plugin statement the page is getting displayed. In case I consider that the struts-config.xml doesnt have strutshibernate as the action path, how was it working when the plugin element <plug-in className="roseindia.net.plugin.HibernatePlugIn"></plug-in> was not entered. Could you please solve this for me.

Posted by Prasad Regula on Monday, 09.8.08 @ 20:08pm | #78055

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Code is useful, but try to add execute() template where the actual session factory will going to use.

Posted by chandrakanth on Monday, 08.25.08 @ 11:31am | #74973

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Code is useful ,but it give null pointer exception...plse slove this ..when run

thanks in advance

raghavendra

Posted by raghavendra on Monday, 06.9.08 @ 15:25pm | #62710

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Hi,
I found this tutorial very useful for integrating hibernate with struts.

Regards

Posted by Sanjeev Srinath on Tuesday, 06.3.08 @ 16:32pm | #61954

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When I download and inplement your code I am getting the following error!!
java.lang.NullPointerException
at roseindia.web.SearchTutorialAction.execute(SearchTutorialAction.java:40)
at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)
at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)
at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)
at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:763)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:225)
at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:127)
at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:230)
at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
at com.grems.struts.BasicFilter.doFilter(BasicFilter.java:52)
at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42)
at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3212)
at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321)
at weblogic.security.service.SecurityManager.runAs(SecurityManager.java:121)
at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:1983)
at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:1890)
at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1344)
at weblogic.work.ExecuteThread.execute(ExecuteThread.java:209)
at weblogic.work.ExecuteThread.run(ExecuteThread.java:181)

Please let me know what I have to do.

Posted by Jennie on Thursday, 06.28.07 @ 23:21pm | #20349

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It was nice and useful to novice people

Posted by m.venkatraju on Saturday, 03.17.07 @ 17:58pm | #11998

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Hi,

good one to beginners.

regards
raju

Posted by srinivasaraju on Wednesday, 02.7.07 @ 11:33am | #6541

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nice and usefull to me.
i want more information regarding hibernate

thanks
mahesh

Posted by mahesh on Thursday, 02.1.07 @ 17:25pm | #5219

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