Form 为空的有关问题_J2EE

Form 为空的问题
各位，本人是菜鸟，建了个工程测试struts登录，当点击subset时报空指针，哪位仁兄指点一下。

Java code

package com.isoftstone.Test.form;import javax.servlet.http.HttpServletRequest;import org.apache.struts.action.ActionErrors;import org.apache.struts.action.ActionMapping;import org.apache.struts.validator.ValidatorForm;public class LoginForm extends ValidatorForm {    private String userName;    private String password;    @Override      public void reset(ActionMapping mapping, HttpServletRequest request) {           System.out.println("--------LoginAcionForm.reset()--------");       }       /* (non-Javadoc)       * @see org.apache.struts.action.ActionForm#validate(org.apache.struts.action.ActionMapping, javax.servlet.http.HttpServletRequest)       */      @Override      public ActionErrors validate(ActionMapping mapping,               HttpServletRequest request) {           System.out.println("-----LoginAcitonForm.validate()");   //      UserManager.getInstance().login(username, password);           return null;       }              public String getUserName() {        return userName;    }    public void setUserName(String userName) {        this.userName = userName;    }    public String getPassword() {        return password;    }    public void setPassword(String password) {        this.password = password;    }}

下面是action

Java code

package com.isoftstone.Test.action;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import org.apache.struts.action.Action;import org.apache.struts.action.ActionForm;import org.apache.struts.action.ActionForward;import org.apache.struts.action.ActionMapping;import com.isoftstone.Test.dao.UserDAO;import com.isoftstone.Test.form.LoginForm;public class LoginAction extends Action{        public ActionForward execute(ActionMapping mapping, ActionForm form,                                 HttpServletRequest request, HttpServletResponse response){        LoginForm loginForm = (LoginForm)form;        System.out.println(loginForm.getUserName());        UserDAO dao = new UserDAO();        if(dao.check(loginForm.getUserName())){            return mapping.findForward("success");        }else{            return mapping.findForward("error");        }        }}

这是jsp页面

HTML code

<%@ page language="java" pageEncoding="gb2312"%><%@ taglib uri="http://struts.apache.org/tags-bean" prefix="bean" %><%@ taglib uri="http://struts.apache.org/tags-html" prefix="html" %><%@ taglib uri="http://struts.apache.org/tags-logic" prefix="logic" %><%@ taglib uri="http://struts.apache.org/tags-tiles" prefix="tiles" %><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html:html lang="true">  <head>    <html:base />    <title>login.jsp</title>  </head>  <body>   <form action="/Test/login.do" method="post">     username：<input type=text name="userName" size="15"/><br>    password：<input type=password name="password" size="15"/><br>    <input type="submit" value="submit">    <input type="reset"  value="reset">   </form>   </body></html:html>

------解决方案--------------------
伙计,写代码的时候小心点,
你看看