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SpringMVC拦截器——实现登录验证拦截器的示例代码

2019年07月22日  | 移动技术网IT编程  | 我要评论

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。

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