hand first 设计模式 - 命令模式

命令模式: 将请求封闭成对象,这可以让你使用不同的请求,队列.或者日志请求来参数化其他对象.命令模式式可支持撤销技术操作.

实例需求:
  一个摇控器.可以控制N个电器设备的开关,以及相关的操作.还可以一些组合操作.有一个撤消操作.(需求见附件)

命令接口

public interface Command {
	
	//执行相关命令
         public void execute();
	
         //撤消相关命令
	public void undo();

}

开关接口

public interface Switch {
	
	public void on();
	
	public void off();

}

实例灯

public class Light implements Switch{
	
    private String name;
    
    public Light(String name){
    	this.name = name;
    }
	//开操作
	public void on(){
		System.out.println(name +" is on");
	}
	//关操作
	public void off(){
		System.out.println(name +" is off");
	}

}

开灯命令

public class LightOnCommand implements Command {

	private Light light;

	public LightOnCommand(Light light) {
		this.light = light;
	}

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

	@Override
         //撤消操作.因为灯只有二种状态所以撤消操作就是关灯
	public void undo() {
		// TODO Auto-generated method stub
		light.off();

	}

}

关灯操作

public class LightOffCommand implements Command {
	
	private Light light;
	
	public LightOffCommand(Light light){
		this.light = light;
	}

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

	}

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

	}

}

电视

public class TV implements Switch {

	private String name;

	public TV(String name) {
		this.name = name;
	}

	@Override
	public void off() {
		// TODO Auto-generated method stub
		System.out.println(name + " is off");

	}

	@Override
	public void on() {
		// TODO Auto-generated method stub
		System.out.println(name + " is on");

	}

}

//开电视

public class TVOnCommand implements Command {

	private TV tv;

	public TVOnCommand(TV tv) {
		this.tv = tv;
	}

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

	}

	@Override
	public void undo() {
		// TODO Auto-generated method stub
		tv.off();

	}

}

关电视

public class TVOffCommand implements Command {

	private TV tv;

	public TVOffCommand(TV tv) {
		this.tv = tv;
	}

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

	}

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

	}

}

空命令

public class NoCommand implements Command {

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

	}

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

	}

}

摇控器

public class Controler {
	//有7个电器设置控制接口
         private final static int PROTNUM = 7;
	//开控制命令组
         private Command[] onCommands = new Command[PROTNUM];
	//关控制命令组
         private Command[] offCommands = new Command[PROTNUM];

	private Command noCommand = new NoCommand();
	//一个用于撤消的List
	private static LinkedList<Command> undoList = new LinkedList<Command>();

	public Controler() {
		 //初始化所有命令组有空命令
                   for (int i = 0; i < PROTNUM; i++) {
			onCommands[i] = noCommand;
			offCommands[i] = noCommand;
		}
	}
	

//根据接口号设置开关命令	
public void setProt(int index,Command onCommand,Command offCommand){
		if(index>PROTNUM)
			return;
		onCommands[index] = onCommand;
		offCommands[index] = offCommand;
	}
	
	
//根据接口号执行开命令
public void onButton(int index){
		onCommands[index].execute();
		//增加到撤消的List
                  undoList.add(onCommands[index]);
	}

//根据接口号执行关命令	
public void offBuffon(int index){
		offCommands[index].execute();
                   //增加到撤消的List
		undoList.add(offCommands[index]);
	}
	
//撤消操作
public void undoButton(){
		//取撤消的List的最后一个命令进行撤消
                  Command command = undoList.removeLast();
		command.undo();
	}
	
}

关闭看电视组合命令

public class LookTvOffCommand implements Command {
          //命令组合
	private Command[] commands;

	public LookTvOffCommand(Command[] commands) {
		this.commands = commands;
	}

	@Override
         //执行命令组合
	public void execute() {
		// TODO Auto-generated method stub
		for (Command command : commands) {
			command.execute();
		}

	}

	@Override
         //撤消命令组合
	public void undo() {
		// TODO Auto-generated method stub
		for (Command command : commands) {
			command.undo();
		}

	}

}

开启看电视组合命令

public class LookTvOnCommand implements Command {

	private Command[] commands;

	public LookTvOnCommand(Command[] commands) {
		this.commands = commands;
	}

	@Override
	public void execute() {
		// TODO Auto-generated method stub
		for(Command command:commands){
			command.execute();
		}

	}

	@Override
	public void undo() {
		// TODO Auto-generated method stub
		for(Command command:commands){
			command.undo();
		}

	}

}

测试类

public class Test {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Controler control = new Controler();
		
		Light light = new Light("room light");
		
		TV tv = new TV("romm tv");
		
                  //灯放在摇控器的0号口
		control.setProt(0, new LightOnCommand(light), new LightOffCommand(light));
		
		control.onButton(0);
		
		control.offBuffon(0);
		
		control.undoButton();
		
		//封装看电视的组合命令(关灯,看电视)
		Command[] lookTvOnCommands = {new LightOffCommand(light),new TVOnCommand(tv)};
		//封装不看电视的组合命令
		Command[] lookTvOffCommands = {new LightOnCommand(light),new TVOffCommand(tv)};
		//看电视命令
		LookTvOnCommand lookTvOnCommand = new LookTvOnCommand(lookTvOnCommands);
		//不看电视命令
		LookTvOffCommand lookTvOffCommand  = new LookTvOffCommand(lookTvOffCommands);
		
		control.setProt(1, lookTvOnCommand, lookTvOffCommand);
		
		control.onButton(1);
		
		control.offBuffon(1);
		
		control.undoButton();
		

	}

}

当需要将发出请求的对象和执行请求的对象解耦的时候,使用命令模式.