在Struts中使用PlugIn扩展Hibernate

时间:2021-05-02

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

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