学习日常-SpringMvc之拦截器

新手进行的一个简单拦截器开发
开发工具： IDEA

项目结构

pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>org.example</groupId>
    <artifactId>SSM-StudyDemo</artifactId>
    <packaging>pom</packaging>
    <version>1.0-SNAPSHOT</version>
    <modules>
        <module>SSM-SpringMVc</module>
    </modules>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.5.RELEASE</version>
        </dependency>
        <!--servelt-->
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>4.0.0-b07</version>
            <scope>provided</scope>
        </dependency>

     
    </dependencies>
    <build>
        <finalName>SSM</finalName>
        <resources>
            <resource>
                <directory>src/main/java</directory>
                <includes>
                    <include>**/*.xml
                
            
        
    

实体类

package Com.Demo.pojo;

public class User {
    private Integer id;
    private String username;
    private String password;

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getUsername() {
        return username;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public User() {
    }

    public User(Integer id, String username, String password) {
        this.id = id;
        this.username = username;
        this.password = password;
    }
}

拦截器

package Com.Demo.Config;

import Com.Demo.pojo.User;
import org.springframework.web.servlet.HandlerInterceptor;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;


//拦截器，拦截用户的请求并作出相应的处理
public class LoginExterceptor implements HandlerInterceptor {
    /*
    * preHandle： 该方法会在控制器方法前执行，其返回值表示是否中断后续操作
    * */
    public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
        System.out.println("正在进入preHandle方法");

        HttpSession session = request.getSession(false);
        // 获取session
        User user = (User) session.getAttribute("user");



        if (user ==null){
            //跳转到登录界面
            request.getRequestDispatcher("/WEB-INF/jsp/login.jsp").forward(request,response);
        }

        return true;
    }

    /*
    * postHandle：该方法会在控制器方法调用之后，且解析视图之前执行
    * */
    public void postHandle(HttpServletRequest request, HttpServletResponse response, Object handler, ModelAndView modelAndView) throws Exception {
        System.out.println("正在进入postHandle方法");

    }

    /*
    * afterCompletion： 该方法会在整个请求完成，即视图渲染结束之后执行
    * */
    public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex) throws Exception {

        System.out.println("正在进入afterCompletion方法");
    }
}

控制器

package Com.Demo.Controller;


import Com.Demo.pojo.User;
import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.servlet.ModelAndView;

import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpSession;

@Controller
public class UserController {

    @RequestMapping("/hello")
    public String Test(Model  model){
        model.addAttribute ("msg","HelloWorld");
        System.out.println("控制层");
        return "Hello";
    }


    @RequestMapping("/login")
    public String login(HttpServletRequest request,User user) {
        // 创建Session
        HttpSession session = request.getSession();
        String username = user.getUsername();
        String password = user.getPassword();

        //把用户名和密码存到session域中
        session.setAttribute("user", user);


        return "login";
    }


    @RequestMapping("/welcome")
    public String welcome(){
        return "welcome";
    }
}

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">
    <filter>
        <filter-name>filter</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>filter</filter-name>
        <url-pattern>/*
    


    
        dispatcherServlet
        org.springframework.web.servlet.DispatcherServlet
        
            contextConfigLocation
            classpath:SpringMvc.xml
        
        1
    
    
        dispatcherServlet
        
        /
    

springmvc.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:context="http://www.springframework.org/schema/context"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.3.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd">
    <context:component-scan base-package="Com.Demo.Controller"></context:component-scan>
    <mvc:annotation-driven></mvc:annotation-driven>
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="prefix" value="/WEB-INF/jsp/"/>
        <property name="suffix" value=".jsp"/>
    </bean>

    <!--配置拦截器-->
    <mvc:interceptors>
        <!--拦截器的指定路径-->
        <mvc:interceptor>
            <!--拦截器作用路径，path ="/**" 表示拦截所有路径-->
            <mvc:mapping path="/**"/>
            <!--mvc:exclude-mapping path="" ：指定不需要拦截的对象-->
            <mvc:exclude-mapping path="/login"/>
            <mvc:exclude-mapping path="/welcome"/>
            <!--表示匹配指定路径的请求-->
                    <bean class="Com.Demo.Config.LoginExterceptor"></bean>
        </mvc:interceptor>
    </mvc:interceptors>
</beans>

接下来是：
index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
  <head>
    <title>$Title$</title>
  </head>
  <body>
<a href="/hello">点我进入主页</a>
<a href="/login">登录</a>
  </body>
</html>

Hello.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
${msg}
</body>
</html>

welcome

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<h2>欢迎</h2>
</body>
</html>

login.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
</head>
<body>
<form action="/welcome" method="post">
   用户名: <input type="text" name="username"><br>
    密码:<input type="password" name="password"><br>
    <input type="submit" value="提交"><br>
</form>
</body>
</html>

运行结果