Controller

@Controller 주로 View를 반환하기 위해 사용함

@ResponseBody 컨트롤러에서 데이터를 반환할때 쓴다.

//@ResponseBody예제
@Controller
@RequiredArgsConstructor
public class UserController {

    private final UserService userService;

    @GetMapping(value = "/users")
    public @ResponseBody ResponseEntity<User> findUser(@RequestParam("userName") String userName){
        return ResponseEntity.ok(userService.findUser(user));
    }
    
    @GetMapping(value = "/users/detailView")
    public String detailView(Model model, @RequestParam("userName") String userName){
        User user = userService.findUser(userName);
        model.addAttribute("user", user);
        return "/users/detailView";
    }
}

@RestController

@Controller에 @ResponseBody가 추가된 것이다.

RestController의 주용도는 Json 형태로 객체 데이터를 반환하는것

최근엔 데이터를 응답으로 제공하는 REST API 개발할 때 주로 사용하고, ResponseEntity로 감싸서 반환한다.

package com.sample.coffee.controller;

import com.codestates.coffee.dto.CoffeePatchDto;
import com.codestates.coffee.dto.CoffeePostDto;
import com.codestates.coffee.dto.CoffeeResponseDto;
import com.codestates.coffee.entity.Coffee;
import com.codestates.coffee.mapper.CoffeeMapper;
import com.codestates.coffee.service.CoffeeService;
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.*;

import javax.validation.Valid;
import javax.validation.constraints.Positive;
import java.util.List;
import java.util.stream.Collectors;

@RestController
@RequestMapping("/v5/coffees")
@Validated
public class CoffeeController {
    private CoffeeService coffeeService;
    private CoffeeMapper mapper;

    public CoffeeController(CoffeeService coffeeService, CoffeeMapper coffeeMapper) {
        this.coffeeService = coffeeService;
        this.mapper = coffeeMapper;
    }

    @PostMapping
    public ResponseEntity postCoffee(@Valid @RequestBody CoffeePostDto coffeePostDto) {
        Coffee coffee = coffeeService.createCoffee(mapper.coffeePostDtoToCoffee(coffeePostDto));

        return new ResponseEntity<>(mapper.coffeeToCoffeeResponseDto(coffee), HttpStatus.CREATED);
    }

    @PatchMapping("/{coffee-id}")
    public ResponseEntity patchCoffee(@PathVariable("coffee-id") @Positive long coffeeId,
                                      @Valid @RequestBody CoffeePatchDto coffeePatchDto) {
        coffeePatchDto.setCoffeeId(coffeeId);
        Coffee coffee = coffeeService.updateCoffee(mapper.coffeePatchDtoToCoffee(coffeePatchDto));

        return new ResponseEntity<>(mapper.coffeeToCoffeeResponseDto(coffee), HttpStatus.OK);
    }

    @GetMapping("/{coffee-id}")
    public ResponseEntity getCoffee(@PathVariable("coffee-id") long coffeeId) {
        Coffee coffee = coffeeService.findCoffee(coffeeId);

        return new ResponseEntity<>(mapper.coffeeToCoffeeResponseDto(coffee), HttpStatus.OK);
    }

    @GetMapping
    public ResponseEntity getCoffees() {
        List<Coffee> coffees = coffeeService.findCoffees();

        List<CoffeeResponseDto> response = mapper.coffeesToCoffeeResponseDtos(coffees);
        return new ResponseEntity<>(response, HttpStatus.OK);
    }

    @DeleteMapping("/{coffee-id}")
    public ResponseEntity deleteCoffee(@PathVariable("coffee-id") long coffeeId) {
        coffeeService.deleteCoffee(coffeeId);

        return new ResponseEntity<>(HttpStatus.NO_CONTENT);
    }
}

• RequestMapping : 메소드들과 요청을 매핑할 때 사용한다.
  공유 매핑으로 클래스 수준에서 사용하거나 엔드 포인트 매핑을 위해 메소드 수준에서 사용할 수 있다.
• PathVariable : REST API에서 URI에 변수가 들어가는걸 실무에서 많이 볼 수 있다.

예를 들면, 아래 URI에서/1234,/4062464가 @PathVariable로 처리해줄 수 있는 부분이다.

http://localhost:8080/api/user/1234

https://music.bugs.co.kr/album/4062464