新建Maven项目

注意archetype选择quickstart

pom.xml

修改App.java

App.java同级目录新增controller包

HelloController.java

package org.example.controller;

import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
@RequestMapping("hello")
public class HelloController {

    @GetMapping("/show")
    public String sayHello(){
        return "helloworld";
    }
}

启动服务

浏览器输入

http://localhost:8080/hello/show