16-拦截器应用-登录拦截判断

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>
<%--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/>




<!--视图解析器-->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver" id="internalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp" />
    </bean>
    
<!--拦截器配置-->
<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

<!--拦截器配置-->
<mvc:interceptors>
    <mvc:interceptor>
        <mvc:mapping path="/user/**"/>
        <bean class="com.kuang.config.LoginIntercepetor"/>
    </mvc:interceptor>
</mvc:interceptors>
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