本例实现登陆时的验证拦截，采用SpringMVC拦截器来实现
当用户点击到网站主页时要进行拦截，用户登录了才能进入网站主页，否则进入登陆页面
核心代码
首先是index.jsp,显示链接
<%@ 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%>" rel="external nofollow" >
<title>首页</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" rel="external nofollow" >
-->
</head>
<body>
<div style="margin:0 auto;padding-top:100px;font-size:18px;" align="center">
<p><a href="loginpage.html" rel="external nofollow" >登陆</a></p>
<p><a href="user/home.html" rel="external nofollow" >用户中心</a></p>
<p><a href="exception.html" rel="external nofollow" >触发异常</a></p>
</div>
</body>
</html>
controller类
package com.jikexueyuan.demo.springmvc.lesson4.controller;
import javax.annotation.Resource;
import javax.servlet.http.HttpServletRequest;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestMethod;
import org.springframework.web.bind.annotation.RequestParam;
import com.jikexueyuan.demo.springmvc.lesson4.constant.Global;
import com.jikexueyuan.demo.springmvc.lesson4.exception.MyException;
import com.jikexueyuan.demo.springmvc.lesson4.model.User;
import com.jikexueyuan.demo.springmvc.lesson4.service.LoginService;
/**
* 这个例子讲解了如何定义MVC三层注解，使用@Resource进行注入，以及使用@RequestMapping、@RequestParam 、@SessionAttributes
*/
@Controller
public class LoginController extends BaseController {
@Resource
LoginService service;
@Resource
HttpServletRequest request;
@RequestMapping("/exception")
public void exception() throws MyException{
throw new MyException("测试springmvc中的异常捕获");
}
@RequestMapping("/loginpage")
public String toLoginPage(){
return "/WEB-INF/jsp/login.jsp";
}
@RequestMapping("/user/home")
public String toUserHome(){
return "/WEB-INF/jsp/userhome.jsp";
}
@RequestMapping("/logout")
public String logout(){
request.getSession().removeAttribute(Global.USER_SESSION_KEY);
return "redirect:/";
}
@RequestMapping(value = "/doLogin", method = RequestMethod.POST)
public String doLogin(@RequestParam String userName, @RequestParam String password){
try {
User user = service.doLogin(userName, password);
request.getSession().setAttribute(Global.USER_SESSION_KEY, user);
return "redirect:/user/home.html";
} catch (Exception e) {
return "/WEB-INF/jsp/login.jsp";
}
}
}
当点击用户中心时，触发拦截，相关配置如下
在spring-mvc.xml中加上拦截配置，拦截所有URL中包含/user/的请求，当然请求用户中心时就会触发这个拦截器了
<mvc:interceptors>
<mvc:interceptor>
<!-- 拦截所有URL中包含/user/的请求 -->
<mvc:mapping path="/user/**"/>
<bean class="com.jikexueyuan.demo.springmvc.lesson4.interceptor.LoginInterceptor"></bean>
</mvc:interceptor>
</mvc:interceptors>
然后是bean指向的具体的interceptor类，如果session保存的用户信息为null，则跳到login页面，postHandle和afterCompletion方法都不执行，反之都执行。
package com.jikexueyuan.demo.springmvc.lesson4.interceptor;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import com.jikexueyuan.demo.springmvc.lesson4.constant.Global;
public class LoginInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
Object user = request.getSession().getAttribute(Global.USER_SESSION_KEY);
if (user == null) {
System.out.println("尚未登录，调到登录页面");
response.sendRedirect("/loginpage.html");
return false;
}
return true;
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
System.out.println("postHandle");
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
System.out.println("afterCompletion");
}
}
至此，简单的springmvc拦截器就完成了。
