프록시 - 프록시 패턴(기능 추가)

public interface Component {
    String operation();
}

@Slf4j
public class RealComponent implements Component {
    @Override
    public String operation() {
        log.info("RealComponent 실행");
        return "data";
    }
}

@Slf4j
public class DecoratorPatternClient {

    private Component component;

    public DecoratorPatternClient(Component component) {
        this.component = component;
    }

    public void execute() {
        String result = component.operation();
        log.info("result={}", result);
    }
}

@Slf4j
public class MessageDecorator implements Component {

    private Component component;

    public MessageDecorator(Component component) {
        this.component = component;
    }

    @Override
    public String operation() {
        log.info("MessageDecorator 실행");

        //data -> *****data*****
        String result = component.operation();
        String decoResult = "*****" + result + "*****";
        log.info("MessageDecorator 꾸미기 적용 전={}, 적용 후={}", result, decoResult);
        return decoResult;
    }
}

@Test
void noDecorator() {
    RealComponent realComponent = new RealComponent();
    DecoratorPatternClient client = new DecoratorPatternClient(realComponent);
    client.execute();
}

@Test
void decorator1() {
    RealComponent realComponent = new RealComponent();
    MessageDecorator messageDecorator = new MessageDecorator(realComponent);
    DecoratorPatternClient client = new DecoratorPatternClient(messageDecorator);
    client.execute();
}

- 데코레이터 패턴으로 값을 꾸미는 기능을 추가 할 수 있다.

 

 

@Slf4j
public class TimeDecorator implements Component {

    private Component component;

    public TimeDecorator(Component component) {
        this.component = component;
    }

    @Override
    public String operation() {
        log.info("TimeDecorator 실행");
        long startTime = System.currentTimeMillis();

        String result = component.operation();

        long endTime = System.currentTimeMillis();
        long resultTime = endTime - startTime;
        log.info("TimeDecorator 종료 resultTime={}ms", resultTime);
        return result;
    }
}

@Test
void decorator2() {
    RealComponent realComponent = new RealComponent();
    MessageDecorator messageDecorator = new MessageDecorator(realComponent);
    TimeDecorator timeDecorator = new TimeDecorator(messageDecorator);
    DecoratorPatternClient client = new DecoratorPatternClient(timeDecorator);
    client.execute();
}

- 걸리는 시간을 구하는 기능을 하나 더 추가하여 데코레이터를 추가하였다. 데코레이터는 이렇게 체인으로 계속 추가할 수가 있다.