设计模式之命令模式

public class RemoteLoader {

    public static void main(String[] args) {

        RemoteControl remoteControl = new RemoteControl();

        Light light = new Light("Living Room");
        TV tv = new TV("Living Room");
        Stereo stereo = new Stereo("Living Room");
        Hottub hottub = new Hottub();
 
        LightOnCommand lightOn = new LightOnCommand(light);
        StereoOnCommand stereoOn = new StereoOnCommand(stereo);
        TVOnCommand tvOn = new TVOnCommand(tv);
        HottubOnCommand hottubOn = new HottubOnCommand(hottub);
        LightOffCommand lightOff = new LightOffCommand(light);
        StereoOffCommand stereoOff = new StereoOffCommand(stereo);
        TVOffCommand tvOff = new TVOffCommand(tv);
        HottubOffCommand hottubOff = new HottubOffCommand(hottub);

        Command[] partyOn = { lightOn, stereoOn, tvOn, hottubOn};
        Command[] partyOff = { lightOff, stereoOff, tvOff, hottubOff};
  
        MacroCommand partyOnMacro = new MacroCommand(partyOn);
        MacroCommand partyOffMacro = new MacroCommand(partyOff);
 
        remoteControl.setCommand(0, partyOnMacro, partyOffMacro);
  
        System.out.println(remoteControl);
        System.out.println("--- Pushing Macro On---");
        remoteControl.onButtonWasPushed(0);
        System.out.println("--- Pushing Macro Off---");
        remoteControl.offButtonWasPushed(0);
    }
}

RemoteControl.java

public class RemoteControl {
    Command[] onCommands;
    Command[] offCommands;
    Command undoCommand;
 
    public RemoteControl() {
        onCommands = new Command[7];
        offCommands = new Command[7];
 
        Command noCommand = new NoCommand();
        for(int i=0;i<7;i++) {
            onCommands[i] = noCommand;
            offCommands[i] = noCommand;
        }
        undoCommand = noCommand;
    }
  
    public void setCommand(int slot, Command onCommand, Command offCommand) {
        onCommands[slot] = onCommand;
        offCommands[slot] = offCommand;
    }
 
    public void onButtonWasPushed(int slot) {
        onCommands[slot].execute();
        undoCommand = onCommands[slot];
    }
 
    public void offButtonWasPushed(int slot) {
        offCommands[slot].execute();
        undoCommand = offCommands[slot];
    }

    public void undoButtonWasPushed() {
        undoCommand.undo();
    }
 
    public String toString() {
        StringBuffer stringBuff = new StringBuffer();
        stringBuff.append("
------ Remote Control -------
");
        for (int i = 0; i < onCommands.length; i++) {
            stringBuff.append("[slot " + i + "] " + onCommands[i].getClass().getName()
                + "    " + offCommands[i].getClass().getName() + "
");
        }
        stringBuff.append("[undo] " + undoCommand.getClass().getName() + "
");
        return stringBuff.toString();
    }
}

LightOnCommand.java

public class LightOnCommand implements Command {
    Light light;

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

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

    public void undo() {
        light.off();
    }
}

Command.java

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