一共4步
1.第一步导入坐标

<dependencies>
        <dependency>
            <groupId>javax.servlet</groupId>
            <artifactId>javax.servlet-api</artifactId>
            <version>3.1.0</version>
            <scope>provided</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-webmvc</artifactId>
            <version>5.2.10.RELEASE</version>
        </dependency>
    </dependencies>

2.定义Controller

package com.itheima.controller;

import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

//2.定义controller
//2.1使用@Controller定义bean
@Controller
public class UserController {
    //2.2设置当前操作的访问路径
    @RequestMapping("/save")
    //2.3设置当前操作的返回值类型
    @ResponseBody
    public String save(){
        System.out.println("user save ...");
     return "{'module':'springmvc'}";
    }
}

3.创建springmvc的配置文件，加载对应的Controller对应的bean

package com.itheima.config;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;

//3.创建springmvc的配置文件，加载对应的Controller对应的bean
@Configuration
@ComponentScan("com.itheima.controller")
public class SpringMvcConfig {
}

4.定义一个servlet容器启动的配置类，在里面加载spring配置

package com.itheima.config;

import org.springframework.web.context.WebApplicationContext;
import org.springframework.web.context.support.AnnotationConfigWebApplicationContext;
import org.springframework.web.servlet.support.AbstractDispatcherServletInitializer;

//4.定义一个servlet容器启动的配置类，在里面加载spring配置
public class ServletContainersInitConfig extends AbstractDispatcherServletInitializer {

    //加载springmvc容器配置
    @Override
    protected WebApplicationContext createServletApplicationContext() {
        AnnotationConfigWebApplicationContext ac = new AnnotationConfigWebApplicationContext();
        ac.register(SpringMvcConfig.class);
        return ac;
    }

    //设置哪些请求归属springMVC处理
    @Override
    protected String[] getServletMappings() {
        return new String[]{"/"};
    }

    //加载spring容器配置
    @Override
    protected WebApplicationContext createRootApplicationContext() {
        return null;
    }
}

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