LoginAction.java
- Java code
package com.cz;import com.opensymphony.xwork2.Action;public class LoginAction implements Action{ private UserBean user; private String tip; public void setUser(UserBean user){ this.user=user; } public UserBean getUser(){ return this.user; } public void setTip(String tip){ this.tip=tip; } public String getTip(){ return this.tip; } @Override public String execute() throws Exception { // TODO Auto-generated method stub System.out.println("hello"); if(this.getUser().getUsername().equals("cz")&&this.getUser().getPassword().equals("fzqkxeqm")){ this.setTip("登录成功"); return SUCCESS; }else{ this.setTip("登录失败"); return ERROR; } }}- Java code
package com.cz;import java.util.Map;import ognl.DefaultTypeConverter;public class MyConverter extends DefaultTypeConverter{ //类型转换器必须重写convertValue方法，该方法需要完成双向转换 @Override public Object convertValue(Map context,Object value,Class toType){ if(UserBean.class==toType){ String[] params = (String [])value; UserBean user=new UserBean(); String[] userValues=params[0].split(","); user.setUsername(userValues[0]); user.setPassword(userValues[1]); return user; }else if(String.class==toType){ UserBean user=(UserBean)value; return "<"+user.getUsername()+","+user.getPassword()+">"; } return null; }}- Java code
package com.cz;import java.util.Date;public class UserBean { private String username; private String password; public UserBean(){ } 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; } }LoginAction-conversion.properties
user=com.cz.MyConverter
index.jsp
- HTML code
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%><%String path = request.getContextPath();String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";%><!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"><html> <head> <base href="<%=basePath%>"> <title>My JSP 'index.jsp' starting page</title> <meta http-equiv="pragma" content="no-cache"> <meta http-equiv="cache-control" content="no-cache"> <meta http-equiv="expires" content="0"> <meta http-equiv="keywords" content="keyword1,keyword2,keyword3"> <meta http-equiv="description" content="This is my page"> <!-- <link rel="stylesheet" type="text/css" href="styles.css"> --> </head> <body> <h1>请输入您的注册信息</h1> <form method="post" action="./hello/login.action"> 用户名：<input type="text" name="username"><p> 密码：<input type="password" name="password"><p> <input type="submit" value="提交"/> </form> </body> </html>
struts.xml
- XML code
<?xml version="1.0" encoding="UTF-8"?><!DOCTYPE struts PUBLIC "-//Apache Software Foundation//DTD Struts Configuration 2.0//EN" "http://struts.apache.org/dtds/struts-2.0.dtd"><struts> <package name="struts2" namespace="/hello" extends="struts-default"> <!-- Action名字，类以及导航页面定义 --> <!-- 通过Action类处理才导航的Action定义 --> <action name="*" class="com.cz.LoginAction"> <result name="success">/result.jsp</result> <result name="error">/hello/index.jsp</result> </action> </package></struts>
报的错是
- Java code
严重: Servlet.service() for servlet default threw exceptionjava.lang.NullPointerException at com.cz.LoginAction.execute(LoginAction.java:30)
不知道自己建的类型转换器为什么没有作用
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30行是哪一行，明显的空指针啊。。。先把30行列出来给看看
------解决方案--------------------
debug看看进到转换器没先，根据情况再做下一步跟踪计划
------解决方案--------------------
LoginAction-conversion.properties 这个文件和对应action在不在一个包下！
------解决方案--------------------
UserBean这个改成User?
------解决方案--------------------
可以一步步排查，比如先不用converter看是否正常
------解决方案--------------------
if(this.getUser().getUsername().equals("cz")&&this.getUser().getPassword().equals("fzqkxeqm")){
你的这种写法很容易出现空指针异常的，你可以考虑使用if("cz".equals(this.getUser().getUsername()) && "fzqkxeqm".equals(this.getUser().getPassword())){
这样可以避免抛出不必要的空指针异常信息，按照你那种写法，用户必须输入数据才能正常提交，否则必然会出空指针异常，而改成我建议的这种写法之后，即使为空也会当成空串处理而不是空指向……反正就那么回事，解释多了反而搞的我自己都解释不清楚了，呵呵
------解决方案--------------------
先判断下是否为null，在进行下面的方法