导读：本文以实例讲解了如何在Struts中使用PlugIn扩展Hibernate的方法：

使用Struts的PlugIn技术把HibernateＳessionFactory，具体过程如下：

（1）创建HibernateSessionFactory.java，代码如下：

　　package zy.pro.td.util;　　　　import net.sf.hibernate.HibernateException;　　import net.sf.hibernate.Session;　　import net.sf.hibernate.cfg.Configuration;　　　　/**　　* Configures and provides access to Hibernate sessions, tied to the　　* current thread of execution.　Follows the Thread Local Session　　* pattern, see {@link http://hibernate.org/42.html}.　　*/　　public class HibernateSessionFactory {　　　　/**　　* Location of hibernate.cfg.xml file.　　* NOTICE: Location should be on the classpath as Hibernate uses　　* #resourceAsStream style lookup for its configuration file. That　　* is place the config file in a Java package - the default location　　* is the default Java package.<br><br>　　* Examples: <br>　　* <code>CONFIG_FILE_LOCATION = "/hibernate.conf.xml".　　* CONFIG_FILE_LOCATION = "/com/foo/bar/myhiberstuff.conf.xml".</code>　　*/　　private static String CONFIG_FILE_LOCATION = "/hibernate.cfg.xml";　　　　/** Holds a single instance of Session */　　private final ThreadLocal threadLocal = new ThreadLocal();　　　　/** The single instance of hibernate configuration */　　private final Configuration cfg = new Configuration();　　　　/** The single instance of hibernate SessionFactory */　　private net.sf.hibernate.SessionFactory sessionFactory;　　　　/**　　* Returns the ThreadLocal Session instance.　Lazy initialize　　* the <code>SessionFactory</code> if needed.　　*　　*　@return Session　　*　@throws HibernateException　　*/　　public Session currentSession() throws HibernateException {　　Session session = (Session) threadLocal.get();　　　　if (session == null) {　　if (sessionFactory == null) {　　try {　　cfg.configure(CONFIG_FILE_LOCATION);　　sessionFactory = cfg.buildSessionFactory();　　}　　catch (Exception e) {　　System.err.println("%%%% Error Creating SessionFactory %%%%");　　e.printStackTrace();　　}　　}　　session = sessionFactory.openSession();　　threadLocal.set(session);　　}　　　　return session;　　}　　　　/**　　*　Close the single hibernate session instance.　　*　　*　@throws HibernateException　　*/　　public void closeSession() throws HibernateException {　　Session session = (Session) threadLocal.get();　　threadLocal.set(null);　　　　if (session != null) {　　session.close();　　}　　}　　　　/**　　* Default constructor.　　*/　　public HibernateSessionFactory() {　　}　　　　}

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　　（2） 创建HibernatePlugIn.java，代码如下：

　　package zy.pro.td.plugin;　　　　/*　　* Created on Oct 4, 2004　　*　　* To change the template for this generated file go to　　* Window>Preferences>Java>Code Generation>Code and Comments　　*/　　import javax.servlet.ServletException;　　　　import org.apache.struts.action.ActionServlet;　　import org.apache.struts.action.PlugIn;　　import org.apache.struts.config.ModuleConfig;　　　　import javax.naming.Context;　　import javax.naming.InitialContext;　　　　import zy.pro.td.util.HibernateSessionFactory;　　　　/**　　* @author sunil　　*　　*　　This class will initialize hibernate and bind SessionFactory in JNDI at the　　*　　time of application and startup and unbind it from JNDI at the time of application　　*　shutdown　　*/　　public class HibernatePlugin　　implements PlugIn {　　　　private static final String jndi_hibernate = "jndi_hibernate_factory";　　private　 HibernateSessionFactory　hsf;　　private String name;　　　　public HibernatePlugin() {　　hsf=new HibernateSessionFactory();　　}　　　　// This method will be called at the time of application shutdown　　public void destroy() {　　System.out.println("Entering HibernatePlugIn.destroy()");　　//Put hibernate cleanup code here　　System.out.println("Exiting HibernatePlugIn.destroy()");　　}　　　　//This method will be called at the time of application startup　　public void init(ActionServlet actionServlet, ModuleConfig config) throws　　ServletException {　　System.out.println("Entering HibernatePlugIn.init()");　　System.out.println("Value of init parameter " + getName());　　//Uncomment next two lines if you want to throw UnavailableException from your servlet　　//　　　　if(true)　　//　　　　　　throw new ServletException("Error configuring HibernatePlugIn");　　System.out.println("Exiting HibernatePlugIn.init()");　　bindFactoryToJNDI();　　}　　　　private void bindFactoryToJNDI() {　　　　try {　　Context ctx = new InitialContext();　　ctx.bind(this.jndi_hibernate,hsf);　　System.out.println("bindind　the　hibernate　factory　to　JNDI　successfully");　　}　　catch (Exception e) {　　e.printStackTrace();　　}　　}　　　　public String getName() {　　　　return name;　　}　　　　public void setName(String string) {　　name = string;　　}　　}

　　（3） 配置Struts-config.xml,如下：

　　<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE struts-config PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 1.1//EN" "http://jakarta.apache.org/struts/dtds/struts-config_1_1.dtd">　　<struts-config>　　<form-beans>　　<form-bean name="userActionForm" type="zy.pro.td.controller.UserActionForm" />　　</form-beans>　　<action-mappings>　　<action name="userActionForm" path="/act/log/login" scope="request" type="zy.pro.td.controller.LoginAction" />　　</action-mappings>　　<plug-in className="org.apache.struts.tiles.TilesPlugin">　　<set-property property="definitions-config" value="/WEB-INF/tiles-defs.xml" />　　</plug-in>　　<plug-in className="org.apache.struts.validator.ValidatorPlugIn">　　<set-property property="pathnames" value="/WEB-INF/validator-rules.xml,/WEB-INF/validation.xml" />　　</plug-in>　　<plug-in className="zy.pro.td.plugin.HibernatePlugin" />　　<plug-in className="zy.pro.td.plugin.HibernateSessionFactoryPlugIn" />　　</struts-config>　　　　这一部分就是你的嵌入代码

　　（4）创建ActionForm,代码如下：

　　package zy.pro.td.controller;　　　　import org.apache.struts.action.*;　　import javax.servlet.http.*;　　　　public class UserActionForm extends ActionForm {　　private String password;　　private String username;　　public String getPassword() {　　return password;　　}　　public void setPassword(String password) {　　this.password = password;　　}　　public String getUsername() {　　return username;　　}　　public void setUsername(String username) {　　this.username = username;　　}　　public ActionErrors validate(ActionMapping actionMapping, HttpServletRequest httpServletRequest) {　　/**@todo: finish this method, this is just the skeleton.*/　　return null;　　}　　public void reset(ActionMapping actionMapping, HttpServletRequest httpServletRequest) {　　}　　}

　（5）创建Action

　　package zy.pro.td.controller;　　　　import org.apache.struts.action.*;　　import javax.servlet.http.*;　　import javax.naming.Context;　　import javax.naming.InitialContext;　　import net.sf.hibernate.SessionFactory;　　import net.sf.hibernate