@RequiredArgsConstructor

• 생성자 주입 방법
• import lombok.RequiredArgsConstructor; lombok에서 지원하는 기능
  
• 기존 의존성 주입 방식 의존성 주입 방법에는 1. 생성자 2. setter 3. field 3가지 방법이 있음

  1. Constructor (생성자)

     public  class  ExampleCase {
         
         private  final  ChocolateService  chocolateService;
         private  final  DrinkService  drinkService;
         
         @Autowired
         public ExampleCase(ChocolateService  chocolateService, DrinkService  drinkService) {
        	this.chocolateService = chocolateService;
        	this.drinkService = drinkService;
         }
     }

  2. Setter 주입

     public  class  ExampleCase{
         
         	private  ChocolateService  chocolateService;
         	private  DrinkService  drinkService;
         
         	@Autowired
         	public void  setChocolateService(ChocolateService  chocolateService){
         		this.chocolateService = chocolateService;
         	}
         
         	@Autowired
         	public void  setDrinkService(DrinkService  drinkService){
         		this.drinkService = drinkService;
         	}
       

  3. field 주입

     public  class  ExampleCase{
         
         	@Autowired
         	private ChocolateService  chocolateService;
         
         	@Autowired
         	private DrinkService  drinkService;
         }

• @RequiredArgsConstructor 어노테이션을 통한 생성자 주입 방식

  위 기존방식 중 생성자주입의 방법을 보면, 직접 생성자를 생성자를 생성해줘야하는 번거로움이 존재함.

  @RequiredArgsConstructor 어노테이션을 사용하면, 생성자를 만들 때, 필드에 주입해주는 방법으로 동작

  		//롬복이 제공하는 어노테이션을 활용한 방식
  		@Service
      @RequiredArgsConstructor
      public class BannerServiceImpl implements BannerService {
      
          private final BannerRepository bannerRepository;
      
          private final CommonFileUtils commonFileUtils;
          ...
  
  		//기존 생성자를 이용한 방식
  		@Service
      public class BannerServiceImpl implements BannerService {
      
          private BannerRepository bannerRepository;
      
          private CommonFileUtils commonFileUtils;
      
          @Autowired
          public BannerServiceImpl(BannerRepository bannerRepository, CommonFileUtils commonFileUtils) {
              this.bannerRepository = bannerRepository;
              this.commonFileUtils = commonFileUtils;
          }
          ...