22-04-18-책임연쇄패턴-2부-패턴적용하기

22-04-18-책임연쇄패턴-2부-패턴적용하기

목차

01.책임연쇄패턴 적용하기

01.1 RequestHandler

01.2 PrintRequestHandler

01.3 AuthRequestHandler

01.4 LoggingRequestHandler

01.5 Client

01.책임연쇄패턴 적용하기

01.1 RequestHandler

• before

  public class RequestHandler{
    public handler(Request request){
        System.out.println(request.getBody());
    }
  }

• after

  public abstract class RequestHandler{
    private RequestHandler nextHandler;
    public RequestHandler(RequestHandler nextHandler){
        this.nextHandler = nextHandler;
    }
    
    public void handle(Request request){
        if(nextHandler != null){
            nextHandler.handle(request);
        }
    }
  }

01.2 PrintRequestHandler

public class PrintRequestHandler extends RequestHandler{
    private PrintRequestHandler nextHandler;
    public PrintRequestHandler(RequestHandler nextHandler){
       super(nextHandler);
    }
    
    @Override
    public void handle(Request request){
        System.out.println(request.getBody());
        super.handle(request);
    }
}

01.3 AuthRequestHandler

public class AuthRequestHandler extends RequestHandler{
	public AuthRequestHandler(RequestHandler nextHandler){super(nextHandler);}
	@Override
	public void handle(Request request){
		System.out.println("인증이 되었는가?");
		super.handle(request);
	}
}

01.4 LoggingRequestHandler

public class LoggingRequestHandler extends RequestHandler{
	public LoggingRequestHandler(RequestHandler nextHandler){super(nextHandler);}
	@Override
	public void handle(Request request){
		System.out.println("로깅이 되었는가?");
		super.handle(request);
	}
}

01.5 Client

• before

  public class Client{
    public static void main(String[] args){
        Request request = new Request("무궁화 꽃이 피었습니다.");
        RequestHandler requestHandler = new RequestHandler();
        requestHander.handler(request);
    }
  }

• after

  public class Client{
    
    private RequestHandler requestHandler;
    public Client(RequestHandler requestHandler){
        this.requestHandler = requestHandler;
    }
    public void doWork(){
        Request request = new Request("이번 놀이는 뽑기 입니다.");
        requestHandler.handle(request);
  	}
    public static void main(String[] args){
  		RequestHandler chain = new AuthRequestHandler(new LoggingRequestHandler(new PrintRequestHandler(null)));
        Client client = new Client(chain);
        client.doWork();
    }
  }

  • 가장 중요한것은 이렇게 함으로써 클라이언트가 구체적인 핸들러타입을 결정안해도됨
  • 요청을 처리하는 쪽과 디커플되어있음, 타이트하게 묶여있지 않음
• 요청처리, 응답처리할때 많이 쓰인다.