[Spring Boot] 스프링부트 API 성공 및 실패에 대한 HTTP 코드 반환(HttpStatus.OK, HttpStatus.INTERNAL_SERVER_ERROR)

package com.lsj.blog;

import java.util.Random;

import javax.transaction.Transactional;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RestController;

import com.lsj.blog.model.RoleType;
import com.lsj.blog.repository.UserRepository;
import com.lsj.dto.ResponseDto;

@RestController
public class DummyController {

	@Autowired // DI
	private UserRepository userRepository;
	
	@PostMapping("/api/user")
	@Transactional
	public ResponseDto<String> save(@RequestBody BlogUser user){

		BlogUser usre2 = new BlogUser();
		
		Random random = new Random();

		usre2.setUsername(String.valueOf(random.nextInt(10)));
		usre2.setPassword("12345"); 
		usre2.setEmail("abc@naver.com");
		userRepository.save(usre2); 
			
		new ResponseDto<String>(HttpStatus.OK.value(), "데이터 insert에 성공했습니다.");
		// HttpStatus.OK.value() → 200이라는 코드 반환 (정상 성공)
	}
}

package com.lsj.blog.handler;

import org.springframework.http.HttpStatus;
import org.springframework.web.bind.annotation.ControllerAdvice;
import org.springframework.web.bind.annotation.ExceptionHandler;
import org.springframework.web.bind.annotation.RestController;

import com.lsj.dto.ResponseDto;

@ControllerAdvice // 어떤 Exception이 오든 이 페이지로 오게 된다.
@RestController
public class GlobalExceptionHandler {
	
	@ExceptionHandler(value=Exception.class) // 모든 부모 Exception
	public ResponseDto<String> handleException(Exception e) {
		return new ResponseDto<String>(HttpStatus.INTERNAL_SERVER_ERROR.value(),e.getMessage());
		// HttpStatus.INTERNAL_SERVER_ERROR.value() → 500 코드 반환 (서버 에러)
		//return "<h1>" + e.getMessage() + "</h1>";
	}
}

package com.lsj.dto;

import org.springframework.http.HttpStatus;

import lombok.AllArgsConstructor;
import lombok.Builder;
import lombok.Data;
import lombok.NoArgsConstructor;

@Data
@NoArgsConstructor
@AllArgsConstructor
@Builder
public class ResponseDto<T> {
	int status;
//	HttpStatus status;
	T data;
}