Hello,SpringBoot.

package com.example.demo;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
              
@SpringBootApplication
@RestController
public class DemoApplication {
                
                  
    public static void main(String[] args) {
        SpringApplication.run(DemoApplication.class, args)
    }
                  
    @GetMapping("/hello")
    public String hello(@RequestParam(value = "name", defaultValue = "World") String name) {
        return String.format("Hello %s!", name);
    }
                
}