拦截器应用-登录拦截判断
效果就是
登录成功的话展示首页,并且可以在导航栏上直接写请求访问
加了拦截器后
没有登录不能直接进入首页 注销后会跳转到登录页面,并且不能在导航栏上直接写请求访问
第一步 导入pom依赖
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>5.2.0.RELEASE</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
</dependency>
<dependency>
<groupId>javax.servlet.jsp</groupId>
<artifactId>jsp-api</artifactId>
<version>2.2</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>jstl</artifactId>
<version>1.2</version>
</dependency>
</dependencies>
<build>
<resources>
<resource>
<directory>src/main/java</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
<resource>
<directory>src/main/resources</directory>
<includes>
<include>**/*.properties</include>
<include>**/*.xml</include>
</includes>
<filtering>false</filtering>
</resource>
</resources>
</build>
第二步 jsp页面
index.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>$Title$</title>
</head>
<body>
<h1><a href="${pageContext.request.contextPath}/user/goLogin"> 登录页面</a></h1>
<a href="${pageContext.request.contextPath}/user/main">首页</a>
</body>
</html>
login.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
<%--在WEB-INF下的所有资源或者页面,只能通过controller,或者servlet进行访问--%>
<h1> 登陆页面 </h1>
<form action="${pageContext.request.contextPath}/user/login" method="post">
用户名:<input type="text" name="username" />
密码:<input type="text" name="password" />
<input type="submit">
</form>
</body>
</html>
main.jsp
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
<title>Title</title>
</head>
<body>
首页
${msg}
<a href="${pageContext.request.contextPath}/user/logout">注销</a>
</body>
</html>
第三步 web.xml
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://xmlns.jcp.org/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://xmlns.jcp.org/xml/ns/javaee http://xmlns.jcp.org/xml/ns/javaee/web-app_4_0.xsd"
version="4.0">
<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:applicationContext.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
<filter>
<filter-name>encoding</filter-name>
<filter-class>org.springframework.web.filter.CharacterEncodingFilter</filter-class>
<init-param>
<param-name>encoding</param-name>
<param-value>utf-8</param-value>
</init-param>
</filter>
<filter-mapping>
<filter-name>encoding</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
</web-app>
第四步 applicationContext.xml
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans.xsd
http://www.springframework.org/schema/mvc
https://www.springframework.org/schema/mvc/spring-mvc.xsd
http://www.springframework.org/schema/context
https://www.springframework.org/schema/context/spring-context.xsd">
<context:component-scan base-package="com.kuang.controller"/>
<mvc:default-servlet-handler/>
<mvc:annotation-driven/>
<bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver">
<property name="prefix" value="/WEB-INF/jsp/"/>
<property name="suffix" value=".jsp" />
</bean>
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/user/**"/>
<bean class="com.kuang.config.LoginIntercepetor"/>
</mvc:interceptor>
</mvc:interceptors>
</beans>
第五步 controller
package com.kuang.controller;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import javax.servlet.http.HttpSession;
@Controller
@RequestMapping("/user")
public class LoginController {
@RequestMapping("/main")
public String main(){
return "main";
}
@RequestMapping("/goLogin")
public String login(){
return "login";
}
@RequestMapping("/login")
public String login(HttpSession session, String username, String password,Model model){
session.setAttribute("userLoginInfo",username);
model.addAttribute("msg",username);
return "main";
}
@RequestMapping("/logout")
public String logout(HttpSession session){
session.removeAttribute("userLoginInfo");
return "main";
}
}
第六步 LoginIntercepetor
package com.kuang.config;
import org.springframework.web.servlet.HandlerInterceptor;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;
public class LoginIntercepetor implements HandlerInterceptor {
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
HttpSession session = request.getSession();
if(request.getRequestURI().contains("goLogin")){
return true;
}
if(request.getRequestURI().contains("login")){
return true;
}
if(session.getAttribute("userLoginInfo")!=null){
return true;
}
request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request,response);
return false;
}
}
第七步 在applicationContext.xml配置拦截器
<mvc:interceptors>
<mvc:interceptor>
<mvc:mapping path="/user/**"/>
<bean class="com.kuang.config.LoginIntercepetor"/>
</mvc:interceptor>
</mvc:interceptors>