命令模式(command pattern) 详细解释

本文地址: http://blog.csdn.net/caroline_wendy

命令模式: 将请求封装成对象, 以便使用不同的请求\队列\日志来參数化其它对象. 命令模式也支持可撤销操作.

命令模式:

调用者(Invoker);

命令(Command): 可运行方法(execute), 详细命令(Concrete Command);

接受者(Receiver): 调用命令(Set Command);

详细方法:

1. 详细对象.

/**
 * @time 2014年6月9日
 */
package command;

/**
 * @author C.L.Wang
 *
 */
public class Light {

	public Light() {}
	
	public void on() {
		System.out.println("Light is on");
	}
	
	public void off() {
		System.out.println("Light is off");
	}
	
}


/**
 * @time 2014年6月9日
 */
package command;

/**
 * @author C.L.Wang
 *
 */
public class GarageDoor {
	
	public GarageDoor() {}

	public void up() {
		System.out.println("Garage Door is Open");
	}

	public void down() {
		System.out.println("Garage Door is Closed");
	}

	public void stop() {
		System.out.println("Garage Door is Stopped");
	}

	public void lightOn() {
		System.out.println("Garage light is on");
	}

	public void lightOff() {
		System.out.println("Garage light is off");
	}
}

/**
 * @time 2014年6月9日
 */
package command;

/**
 * @author C.L.Wang
 *
 */
public interface Command {
	public void execute();
}

3. 详细命令(concrete command), 继承命令接口, 实现接口的方法.

/**
 * @time 2014年6月9日
 */
package command;

/**
 * @author C.L.Wang
 *
 */
public class LightOnCommand implements Command {

	Light light;
	
	public LightOnCommand (Light light) {
		this.light = light;
	}
	
	/* (non-Javadoc)
	 * @see command.Command#execute()
	 */
	@Override
	public void execute() {
		// TODO Auto-generated method stub
		light.on();
	}

}



/**
 * @time 2014年6月9日
 */
package command;

/**
 * @author C.L.Wang
 *
 */
public class GarageDoorOpenCommand implements Command {
	
	GarageDoor garageDoor;
	
	public GarageDoorOpenCommand (GarageDoor garageDoor) {
		this.garageDoor = garageDoor;
	}
	
	/* (non-Javadoc)
	 * @see command.Command#execute()
	 */
	@Override
	public void execute() {
		// TODO Auto-generated method stub
		garageDoor.up();
	}

}

/**
 * @time 2014年6月9日
 */
package command;

/**
 * @author C.L.Wang
 *
 */
public class SimpleRemoteControl {
	
	Command slot;
	
	public SimpleRemoteControl() {}
	
	public void setCommand(Command command) {
		this.slot = command;
	}
	
	public void buttonWasPressed() {
		slot.execute();
	}
}

/**
 * @time 2014年6月9日
 */
package command;

/**
 * @author C.L.Wang
 *
 */
public class RemoteControlTest {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		SimpleRemoteControl remote = new SimpleRemoteControl();
		Light light = new Light();
		GarageDoor garageDoor = new GarageDoor();
		LightOnCommand lightOn = new LightOnCommand(light);
		GarageDoorOpenCommand garageOpen = 
				new GarageDoorOpenCommand(garageDoor);
		
		remote.setCommand(lightOn);
		remote.buttonWasPressed();
		remote.setCommand(garageOpen);
		remote.buttonWasPressed();
		
	}

}