SERVICE 생성

package com.cos.blog.service;

@Service
public class UserService {
	
	@Autowired
	private UserRepository userRepository;

	@Transactional
	public void 회원가입(User user ) {
		userRepository.save(user);
	}
}

RestController

@RestController
public class UserApiController {

	
	@Autowired
	private UserService userService;
	
    @PostMapping("/api/user")
	public ResponseDto<Integer> save(@RequestBody User user) {
		System.out.println("save 호출");
        user.setRole(RoleType.USER);
		userService.회원가입(user);
		return new ResponseDto<Integer>(HttpStatus.OK.value(),1); 
		// jackson을 통해 자동으로 json 으로 전달
	}
}