001：SpringBoot-HelloWord

启动项：

@SpringBootApplication

public class App {

    public static void main(String[] args) {

        SpringApplication.run(App.class, args);

    }

}

输出项：

@RestController

public class HelloController {

    @RequestMapping("/")

    public String hello(){

        return "Hello world!";

     }

}

访问路径：http://127.0.0.1:8080/