【JavaEE案例】Spring MVC的核心类和注解

案例介绍

在客户端发送GET、POST、PUT、DELETE请求，由Spring MVC接收请求并响应。

案例实现

 

1.利用Maven创建一个web应用 

参考步骤1

2.引入对Spring和SpringMVC的依赖pom.xml

<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/maven-v4_0_0.xsd">
  <modelVersion>4.0.0</modelVersion>

  <groupId>com.itheima</groupId>
  <artifactId>SpringMVC</artifactId>
  <packaging>war</packaging>

  <version>1.0-SNAPSHOT</version>
  <name>SpringMVC Maven Webapp</name>
  <url>http://maven.apache.org</url>
  <dependencies>
    <dependency>
      <groupId>junit</groupId>
      <artifactId>junit</artifactId>
      <version>4.13.2</version>
      <scope>test</scope>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-context</artifactId>
      <version>5.3.16</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-test</artifactId>
      <version>5.3.16</version>
    </dependency>
    <dependency>
      <groupId>org.springframework</groupId>
      <artifactId>spring-webmvc</artifactId>
      <version>5.3.16</version>
    </dependency>
    <!-- servlet -->
    <dependency>
      <groupId>javax.servlet</groupId>
      <artifactId>javax.servlet-api</artifactId>
      <version>4.0.1</version>
      <scope>provided</scope>
    </dependency>
    <!--JSP-->
    <dependency>
      <groupId>javax.servlet.jsp</groupId>
      <artifactId>javax.servlet.jsp-api</artifactId>
      <version>2.3.3</version>
      <scope>provided</scope>
    </dependency>
  </dependencies>
  <build>
    <finalName>SpringMVC</finalName>
  </build>
</project>

3.配置web运行的Tomcat服务器

参考1.配置Web运行的Tomcat服务器和2.Tomcat:HTTP状态 404

4.配置前端控制器web.xml：Spring MVC通过前端控制器拦截客户端的请求并进行转发

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<!DOCTYPE web-app PUBLIC
        "-//Sun Microsystems, Inc.//DTD Web Application 2.3//EN"
        "http://java.sun.com/dtd/web-app_2_3.dtd" >

<web-app>
  <display-name>Restful Api Application</display-name>
  <servlet>
    <servlet-name>app</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>app</servlet-name>
    <url-pattern>/</url-pattern>
  </servlet-mapping>
</web-app>

5.配置处理器映射信息和视图解析器applicationContext.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       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.xsd">
    <!-- 配置 Spring MVC 要扫描的包 -->
    <context:component-scan base-package="com.itheima.controllers"/>
    <!-- 配置视图解析器 -->
    <bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <!--property name="prefix" value="/WEB-INF/pages/"/>
        <property name="suffix" value=".jsp"/-->
    </bean>
</beans>

6.创建处理器UserController.java：用于处理客户端的请求并指定响应时跳转的页面

package com.itheima.controllers;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.*;

@Controller
@RequestMapping("/user")
public class UserController {
    @GetMapping(value="/1")
    public void getUserById() {
        System.out.println("Find user with id 1");
    }

    @PostMapping
    public void addUser(String username) {
        System.out.println("Add " + username);
    }

    @PutMapping(value="/1")
    public void updateUser() {
        System.out.println("Update a user with id 1");
    }

    @DeleteMapping (value="/1")
    public void deleteUser() {
        System.out.println("Delete a user with id 1");
    }
}

7.启动项目并测试应用：在IDEA中运行程序，复制网址到Apifox中，（打开Apifox→新建接口），点击'发送'按钮，回到IDEA查看运行结果。

测试工具Apifox下载