【SSM】SpringMVC(三：SpringMVC拦截器)
文章目录
- 1. 登录案例
- 2. 拦截器
-
- 2.1 应用
- 2.2 拦截器的执行原理
- 2.3 拦截器执行的时机
- 2.4 拦截器的实现方法
- 2.5 拦截器的实现步骤
- 2.6 开发拦截器
1. 登录案例
【login.jsp】
<%--
Created by IntelliJ IDEA.
User: Beyong
Date: 2023/4/17
Time: 11:43
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<h2>登录</h2>
<form action="${pageContext.request.contextPath}/login">
姓名：<input name="name"/>
密码：<input type="password" name="pwd"/>
<input type="submit" value="登录"/>
</form>
${msg}
</body>
</html>
【main.jsp】
<%--
Created by IntelliJ IDEA.
User: Beyong
Date: 2023/4/15
Time: 21:55
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>main</title>
</head>
<body>
<h1>欢迎来到主页</h1>
</body>
</html>
【WebInfAction.java】
package com.sdnu.controller;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.http.HttpServletRequest;
@Controller
public class WebInfAction {
@RequestMapping("/main")
public String main(){
System.out.println("访问main.jsp");
return "main";
}
@RequestMapping("/showLogin")
public String showLogin(){
System.out.println("访问login.jsp");
return "login";
}
//登录逻辑判断
@RequestMapping("/login")
public String login(String name, String pwd, HttpServletRequest httpServletRequest){
if("xy".equalsIgnoreCase(name) && "123".equalsIgnoreCase(pwd)){
return "main";
} else {
httpServletRequest.setAttribute("msg", "用户名或者密码不正确");
return "login";
}
}
}
2. 拦截器
2.1 应用
日志 权限 性能
2.2 拦截器的执行原理
2.3 拦截器执行的时机
1)preHandle():在请求被处理之前进行操作
2)postHandle():在请求被处理之后,但结果还没有渲染前进行操作,可以改变响应结果
3)afterCompletion:所有的请求响应结束后执行善后工作,清理对象,关闭资源
2.4 拦截器的实现方法
1)继承HandlerInterceptorAdapter的父类
2)实现HandlerInterceptor接口,实现的接口,推荐使用实现接口的方式
2.5 拦截器的实现步骤
1）改造登录方法，在session中存储用户的信息，用于进行权限的验证
2）开发拦截器的功能，实现HandlerInterceptor接口，重写preHandle()方法
3）在springmvc.xml中注册拦截器
2.6 开发拦截器
package com.sdnu.interceptor;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
public class LoginInterceptor implements HandlerInterceptor {
@Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
//判断是否登陆过
if(request.getSession().getAttribute("user") == null){
//此时没有登陆过，返回到登录页面
request.setAttribute("msg", "您还没有登录过，请重新登录");
request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request, response);
return false;
}
return true;
}
@Override
public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
HandlerInterceptor.super.postHandle(request, response, handler, modelAndView);
}
@Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {
HandlerInterceptor.super.afterCompletion(request, response, handler, ex);
}
}
springmvc的配置文件中注册拦截器
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/**"/>
<mvc:exclude-mapping path="/showLogin"/>
<mvc:exclude-mapping path="/login"/>
<bean class="com.sdnu.interceptor.LoginInterceptor"/>
mvc:interceptor>
mvc:interceptors>