构建RESTful Web服务
本指南将手把手教您如何使用Spring框架创建一个“Hello，World”RESTful网络服务。
1、创建一个数据类Greeting，

package com.example.restservice;

public record Greeting(long id, String content) { }

2、创建一个控制器GreetingController，

package com.example.restservice;

import java.util.concurrent.atomic.AtomicLong;

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

@RestController
public class GreetingController {

  private static final String template = "Hello, %s!";
  private final AtomicLong counter = new AtomicLong();

  @GetMapping("/greeting")
  public Greeting greeting(@RequestParam(defaultValue = "World") String name) {
    return new Greeting(counter.incrementAndGet(), template.formatted(name));
  }
}

3、启动服务类

package com.example.restservice;

import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
public class RestServiceApplication {

  public static void main(String[] args) {
    SpringApplication.run(RestServiceApplication.class, args);
  }

}

4、编译，打包，并启动服务。

java -jar build/libs/gs-rest-service-0.1.0.jar

5、测试运行。
浏览器访问地址 http://localhost:8080/greeting
返回结果如下 {"id":1,"content":"Hello, World!"}