图解Java设计模式之命令模式

package com.example.demo.command;

/**
 * 创建命令接口
 * @author zhaozhaohai
 *
 */
public interface Command {
	
	/**
	 * 执行动作（操作）
	 */
	public void execute();

	/**
	 * 撤销动作（操作）
	 */
	public void undo();
}
package com.example.demo.command;

public class LightOffCommand implements Command{
	
	/**
	 * 聚合LightReceiver
	 */
	private LightReceiver LightReceiver;
	
	public LightOffCommand(LightReceiver lightReceiver) {
		this.LightReceiver = lightReceiver;
	}

	@Override
	public void execute() {
		// TODO Auto-generated method stub
		LightReceiver.off();
	}

	@Override
	public void undo() {
		// TODO Auto-generated method stub
		LightReceiver.on();
	}

}
package com.example.demo.command;

public class LightOnCommand implements Command{

	/**
	 * 聚合LightReceiver
	 */
	private LightReceiver LightReceiver;
	
	public LightOnCommand(LightReceiver lightReceiver) {
		this.LightReceiver = lightReceiver;
	}

	@Override
	public void execute() {
		// TODO Auto-generated method stub
		// 调用接收者方法
		LightReceiver.on();
	}

	@Override
	public void undo() {
		// TODO Auto-generated method stub
		// 调用接收者方法
		LightReceiver.off();
	}

}
package com.example.demo.command;

public class LightReceiver {

	public void on() {
		System.out.println(" 电灯打开了。。。 ");
	}
	
	public void off() {
		System.out.println(" 电灯关闭了。。。 ");
	}
}
package com.example.demo.command;

/**
 * 没有任何命令，即空执行 ：用于初始化每个按钮，当调用空命令时，对象什么都不做其实，这样是一种设计模式，可以省掉对空判断
 * @author zhaozhaohai
 *
 */
public class NoCommand implements Command{

	@Override
	public void execute() {
		// TODO Auto-generated method stub
		
	}

	@Override
	public void undo() {
		// TODO Auto-generated method stub
		
	}

}
package com.example.demo.command;

public class RemoteController {
	
	// 开 按钮的命令数组
	private Command[] onCommands;

	private Command[] offCommands;
	
	// 执行撤销的命令
	private Command undoCommand;
	
	/**
	 * 构造器，完成对按钮初始化
	 */
	public RemoteController() {
		onCommands = new Command[5];
		offCommands = new Command[5];
		
		for (int i = 0;i < 5; i++) {
			onCommands[i] = new NoCommand();
			offCommands[i] = new NoCommand();
		}
	}
	
	/**
	 * 给我们的按钮设置你需要的命令
	 * @param no
	 * @param onCommand
	 * @param offCommand
	 */
	public void setCommand(int no, Command onCommand, Command offCommand) {
		onCommands[no] = onCommand;
		offCommands[no] = offCommand;
	}
	
	/**
	 * 按下开按钮
	 * @param no
	 */
	public void onButtonWasPushed(int no) {
		// 找到你按下的开的按钮，并调用对应的方法
		onCommands[no].execute();
		// 记录这次的操作，用于撤销
		undoCommand = onCommands[no];
	}
	
	/**
	 * 按下关的按钮
	 * @param no
	 */
	public void offButtonWasPushed(int no) {
		// 找到你按下的关的按钮，并调用对应方法
		offCommands[no].execute();
		// 记录这次的操作，用于撤销
		undoCommand = offCommands[no];
	}
	
	/**
	 * 按下撤销按钮
	 */
	public void undoButtonWasPushed() {
		undoCommand.undo();
	}
	
}
package com.example.demo.command;

public class TVOffCommand implements Command{
	/**
	 * 聚合TVReceiver
	 */
	private TVReceiver tvReceiver;
	
	public TVOffCommand(TVReceiver tvReceiver) {
		this.tvReceiver = tvReceiver;
	}

	@Override
	public void execute() {
		// TODO Auto-generated method stub
		tvReceiver.off();
	}

	@Override
	public void undo() {
		// TODO Auto-generated method stub
		tvReceiver.on();
	}
}
package com.example.demo.command;

public class TVOnCommand implements Command{
	/**
	 * 聚合TVReceiver
	 */
	private TVReceiver tvReceiver;
	
	public TVOnCommand(TVReceiver tvReceiver) {
		this.tvReceiver = tvReceiver;
	}

	@Override
	public void execute() {
		// TODO Auto-generated method stub
		tvReceiver.on();
	}

	@Override
	public void undo() {
		// TODO Auto-generated method stub
		tvReceiver.off();
	}
}
package com.example.demo.command;

public class TVReceiver {
	public void on() {
		System.out.println(" 电视机打开了。。。 ");
	}
	
	public void off() {
		System.out.println(" 电视机关闭了。。。 ");
	}
}
package com.example.demo.command;

public class Client {
	
	public static void main(String[] args) {
		// 使用命令设计模式，完成通过遥控器，对电灯的操作
		// 创建电灯的对象（接受者）
		LightReceiver lightReceiver = new LightReceiver();
		// 创建电灯相关的开关命令
		LightOnCommand lightOnCommand = new LightOnCommand(lightReceiver);
		LightOffCommand lightOffCommand = new LightOffCommand(lightReceiver);
		// 需要一个遥控器
		RemoteController remoteController = new RemoteController();
		// 给遥控器设置命令，比如 no = 0 是电灯的开和关的操作
		remoteController.setCommand(0, lightOnCommand, lightOffCommand);
		System.out.println("----------按下开的按钮------------");
		remoteController.onButtonWasPushed(0);
		System.out.println("----------按下关的按钮------------");
		remoteController.offButtonWasPushed(0);
		System.out.println("----------按下撤销的按钮------------");
		remoteController.undoButtonWasPushed();
		System.out.println("----------使用遥控器操作电视机-------");
		
		TVReceiver tvReceiver = new TVReceiver();
		TVOffCommand tvOffCommand = new TVOffCommand(tvReceiver);
		TVOnCommand tvOnCommand = new TVOnCommand(tvReceiver);
		// 给遥控器设置命令，比如 no = 1 是电视机的开和关的操作
		remoteController.setCommand(1, tvOnCommand, tvOffCommand);
		System.out.println("----------按下开的按钮------------");
		remoteController.onButtonWasPushed(1);
		System.out.println("----------按下关的按钮------------");
		remoteController.offButtonWasPushed(1);
		System.out.println("----------按下撤销的按钮------------");
		remoteController.undoButtonWasPushed();
	}

}