1.在WEN-INF文件夹下面，添加一个login.jsp文件
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| <%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>用户登录</title>
</head>
<body>
<form action="user/login" method="post">
用户名:<input type="text" name="username"/><br/>
用户密码:<input type="password" name="password"/><br/>
<input type="submit" value="用户登录"/>
</form>
</body>
</html>
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2.在UserController.java中加入login
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| @RequestMapping(value="/login",method=RequestMethod.POST)
public String login(String username,String password,HttpSession session){
if(!users.containsKey(username)){
throw new UserException("用户名不存在");
}
User u = users.get(username);
if(!u.getPassword().equals(password)){
throw new UserException("用户密码不正确");
}
session.setAttribute("loginUser", u);
return "redirect:/user/users";
}
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3.其中需要new UserException，再创建UserException.java
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| package org.common.model;
public class UserException extends RuntimeException {
/**
*
*/
private static final long serialVersionUID = 1L;
public UserException() {
super();
// TODO Auto-generated constructor stub
}
public UserException(String message, Throwable cause) {
super(message, cause);
// TODO Auto-generated constructor stub
}
public UserException(String message) {
super(message);
// TODO Auto-generated constructor stub
}
public UserException(Throwable cause) {
super(cause);
// TODO Auto-generated constructor stub
}
}
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如果只是做到这些的话，当输出的用户名和密码错误的时候，报错如下图
4.在UserController.java中加入局部异常处理，并在jsp文件夹下面添加error.jsp
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| //局部的异常处理，仅仅只能处理这个控制器中的异常
@ExceptionHandler(value={UserException.class})
public String handlerException(UserException e,HttpServletRequest req) {
req.setAttribute("exception",e);
return "error";
}
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| <%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
发现错误:
<h1>${exception.message}</h1>
</body>
</html>
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这时候如果输入用户名或者密码输入，如下图
另外一种异常处理方法，全局异常
需要把Controller中的局部异常注释掉
然后在user-servlet.xml中加入
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| <!-- 全局异常处理 -->
<bean id="exceptionResolver" class="org.springframework.web.servlet.handler.SimpleMappingExceptionResolver">
<property name="exceptionMappings">
<props>
<prop key="org.common.model.UserException">error</prop>
<prop key="java.lang.nullpointerexception">exception</prop>
</props>
</property>
</bean>
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