JAVA设计模式-命令模式

1、例子

 

3、代码

 

public class RemoteController {
 
    //开 按钮的命令数组
    Command[] onCommands;
    Command[] offComands;
 
    //执行撤销的命令
    Command undoCommand;
 
    //构造器，完成对按钮的初始化
 
 
    public RemoteController() {
 
        onCommands=new Command[5];
        offComands=new Command[5];
 
        for (int i = 0; i < 5; i++) {
            onCommands[i]=new NoCommand();
            offComands[i]=new NoCommand();
        }
    }
        //给我们的按钮设置你需要的命令
    public void setCommand(int no,Command onCommand,Command offComand){
        onCommands[no]=onCommand;
        offComands[no]=offComand;
    }
 
    //按下开按钮
    public void onButtonWasPushed(int no){
        onCommands[no].execute();
        undoCommand=onCommands[no];
    }
 
    //按下开按钮
    public void offButtonWasPushed(int no){
        offComands[no].execute();
        undoCommand=offComands[no];
    }
 
    //按下撤销按钮
    public void undoButtonWasPushed(){
 
        undoCommand.undo();
    }
 
}

 

public class LightOnCommand implements Command {
 
    //聚合LightReceiver
    LightReceiver light;
 
    //构造器
 
 
    public LightOnCommand(LightReceiver light) {
        this.light = light;
    }
 
    @Override
    public void execute() {
        light.on();
    }
 
    @Override
    public void undo() {
        light.off();
    }
}

public class LightOffCommand implements Command {
 
    //聚合LightReceiver
    LightReceiver light;
 
    //构造器
 
 
    public LightOffCommand(LightReceiver light) {
        this.light = light;
    }
 
 
    @Override
    public void execute() {
        light.off();
    }
 
    @Override
    public void undo() {
        light.on();
    }
}

public interface Command {
    public void execute();
    public void undo();
}

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");
    }
}

public class Client {
    public static void main(String[] args) {
        LightReceiver lightReceiver = new LightReceiver();
 
        LightOnCommand lightOnCommand = new LightOnCommand(lightReceiver);
        LightOffCommand lightOffCommand = new LightOffCommand(lightReceiver);
 
        RemoteController remoteController = new RemoteController();
 
        remoteController.setCommand(0,lightOnCommand,lightOffCommand);
        System.out.println("开始");
        remoteController.onButtonWasPushed(0);
        System.out.println("关闭");
        remoteController.offButtonWasPushed(0);
        System.out.println("撤销");
        remoteController.undoButtonWasPushed();
 
 
        System.out.println("___________________");
 
        TVReceiver tvReceiver = new TVReceiver();
 
        TVOffCommand tvOffCommand = new TVOffCommand(tvReceiver);
        TVOnCommand tvOnCommand = new TVOnCommand(tvReceiver);
 
 
        remoteController.setCommand(1,tvOnCommand,tvOffCommand);
 
 
 
        System.out.println("开始");
        remoteController.onButtonWasPushed(1);
        System.out.println("关闭");
        remoteController.offButtonWasPushed(1);
        System.out.println("撤销");
        remoteController.undoButtonWasPushed();
 
 
 
    }
}

总结：把逻辑流程抽象，底部实现类，改为插拔式