CamelAct

Overview

요청을 객체 형태로 캡슐화하여(실행할 함수를 캡슐화하여) 사용자가 요청한 메서드 이름, 매개변수 등의 정보를 나중에 저장, 로깅 또는 사용할 수 있도록 하는 패턴입니다. 요청에 필요한 정보를 취소합니다.
명령 패턴은 항상 명령, 수신자, 호출자 및 클라이언트의 네 가지 용어를 따릅니다.

장점
명령 패턴을 활용하여 요청 부분과 작업 부분을 분리함으로써 시스템의 결합 정도를 낮출 수 있으며, 각 객체가 수정되어도 다른 객체에는 영향을 미치지 않습니다.
클라이언트와 Invoker클래스 간의 종속성이 제거됩니다.

단점
수신자의 액션을 추가하면 액션에 대한 클래스를 생성해야 하므로 잡다한 클래스가 오히려 많이 추가되는 단점이 있습니다.

Structure

Code Example

package com.example.design.pattern;

interface Command {
	public abstract void execute();
}

class Button {
	private Command theCommand;

	public Button(Command theCommand) {
		setCommand(theCommand);
	}

	public void setCommand(Command newCommand) {
		this.theCommand = newCommand;
	}

	public void pressed() {
		theCommand.execute();
	}
}

class Lamp {
	public void turnOn() {
		System.out.println("Lamp On");
	}
}

class LampOnCommand implements Command {
	private Lamp theLamp;

	public LampOnCommand(Lamp theLamp) {
		this.theLamp = theLamp;
	}

	public void execute() {
		theLamp.turnOn();
	}
}

class Alarm {
	public void start() {
		System.out.println("Alarming");
	}
}

class AlarmStartCommand implements Command {
	private Alarm theAlarm;

	public AlarmStartCommand(Alarm theAlarm) {
		this.theAlarm = theAlarm;
	}

	public void execute() {
		theAlarm.start();
	}
}

public class MyCommand {
	public static void main(String[] args) {
		Lamp lamp = new Lamp();
		Command lampOnCommand = new LampOnCommand(lamp);
		Alarm alarm = new Alarm();
		Command alarmStartCommand = new AlarmStartCommand(alarm);

		Button button1 = new Button(lampOnCommand); 
		button1.pressed();

		Button button2 = new Button(alarmStartCommand);
		button2.pressed(); 
		button2.setCommand(lampOnCommand);
		button2.pressed(); 
	}
}

Console Result

Lamp On
Alarming
Lamp On

Conclusion

N/A