java設計模式（六） 命令模式

【命令模式】將”請求“封裝成對象，以便使用不同的請求，隊列或者日誌來參數化其他對象，命令模式也支持可撤銷的操作。

1，定義命令接口

package com.pattern.command;

public interface Command {
	
	public void execute();
	
}

2，接口的實現類

package com.pattern.command;

public class LightOnCommand implements Command{
	Light light;
	
	public LightOnCommand(Light light){
		this.light = light;
	}
	
	/** 
	 * @see com.pattern.command.Command#execute()
	 */
	@Override
	public void execute() {
		light.on();
	}

}

3，命令的具體執行者

package com.pattern.command;

public class Light {
	
	public void on(){
		System.out.println("turn on the light!");
	}

}

4，控制器類

package com.pattern.command;

public class SimpleRemoteControl {
	
	Command slot;
	
	public SimpleRemoteControl(){}
	
	public void setCommand(Command command){
		slot = command;
	}
	
	public void buttonWasPressed(){
		slot.execute();
	}
}

5，測試類

package com.pattern.command;

public class RemoteControlTest {
	
	public static void main(String[] args) {
		SimpleRemoteControl remote = new SimpleRemoteControl();
		Light light = new Light();
		LightOnCommand lightOn = new LightOnCommand(light);
		
		remote.setCommand(lightOn);
		remote.buttonWasPressed();
	}
}

輸出結果：

turn on the light!