//命令模式
public class CommandMode {
    public static void main(String[] args) {
        InstructionSet instructionSet=new InstructionSet();
        Command onCommand = new OnCommand(instructionSet);
       Command offCommand = new OffCommand(instructionSet);
        Controller controller = new Controller();
        //设置命令
        controller.set(0,onCommand,offCommand);
        //开启
        controller.onButton(0);
        //关闭
        controller.offButton(0);
        System.out.println("撤销操作，重新开启!!!!!!!!!");
        controller.undoButton();
    }
}

interface Command {

    //执行动作(操作)
    public void execute();

    //撤销动作(操作)
    public void undo();
}
//执行者
class OnCommand implements Command {
    private InstructionSet instructionSet;

    public OnCommand(InstructionSet instructionSet) {
        this.instructionSet = instructionSet;
    }


    public void execute() {
        instructionSet.on();
    }

    public void undo() {
        instructionSet.off();
    }
}
//执行者
class OffCommand implements Command {
    private InstructionSet instructionSet;

    public OffCommand(InstructionSet instructionSet) {
        this.instructionSet = instructionSet;
    }


    public void execute() {
        instructionSet.off();
    }

    public void undo() {
        instructionSet.on();
    }
}

/**
 * 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
 */
class NoCommand implements Command {


    public void execute() {
    }

    public void undo() {
    }

}

class InstructionSet {
    public void on() {
        System.out.println("摄像头录制功能开启~~~");
    }

    public void off() {
        System.out.println("摄像头录制功能关闭~~~~");
    }
}
//请求发起者
class Controller {
    Command[] onCommands;
    Command[] offCommands;
    Command undoCommand;

    public Controller() {
        onCommands = new Command[5];
        offCommands = new Command[5];

        for (int i = 0; i < 5; i++) {
            onCommands[i] = new NoCommand();
            offCommands[i] = new NoCommand();
        }
    }

    public void set(int o, Command on, Command off) {
        onCommands[o] = on;
        offCommands[o] = off;
    }

    //开启方法
    public void onButton(int o) {
        onCommands[o].execute();
        undoCommand = onCommands[o];
    }

    //关闭方法
    public void offButton(int o) {
        offCommands[o].execute();
        undoCommand = offCommands[o];
    }

    //撤销方法
    public void undoButton() {
        undoCommand.undo();
    }

}