设计模式(6)--命令模式

命令模式应用场景

　　比如有个这样的场景，一个控制器，上面有很多对按钮，一对按钮包括开和关，然后这个可以将一些电器插在这个上面，然后就可以通过这个控制器来进行控制相应的电器。如果以后类似于需要模拟这种场景，你可以参考下这种模式。

命令模式使用步骤

　　1.定义一个命令接口，所有命令都需要是现在这个接口，其主要方法有execute，即执行命令。

public interface Command {

    public void execute();
}

　　2.定义一个电器接口，所有电器实现这个接口，方法主要是有on和off，即打开和关闭。

public interface Device {

    public void on();

    public void off();
}

　　3.编写一些接口实现类，如灯泡、收音机等及其相关命令实现类

//Light.java
public class Light implements Device {

    private String deviceName;

    public Light() {
        deviceName = "Light";
    }

    @Override
    public void on() {
        System.out.println(deviceName + " is twinkling");
    }

    @Override
    public void off() {
        System.out.println(deviceName + " is off");
    }

}

//Radio.java
public class Radio implements Device {

    private String deviceName;
    
    
    public Radio() {
        deviceName = "radio";
    }
    
    @Override
    public void on() {
        System.out.println(deviceName + "is working");
    }

    @Override
    public void off() {
            System.out.println(deviceName + "is over");
    }

}

//CommandOn.java
public class CommandOn implements Command {

    private Device device;

    public CommandOn(Device device) {
        this.device = device;
    }

    @Override
    public void execute() {
        device.on();
    }

}

//CommandOff.java
public class CommandOff implements Command {
    
    private Device device;

    public CommandOff(Device device) {
        this.device = device;
    }
    
    @Override
    public void execute() {
        device.off();
    }

}

　　4.编写控制器

public class RemoteController {

    private Command[] commandsOn;

    private Command[] commandsOff;

    public RemoteController() {
        commandsOn = new Command[7];
        commandsOff = new Command[7];
    }

    public void setCommand(int index, Command on, Command off) {
        commandsOn[index] = on;
        commandsOff[index] = off;
    }

    public void onButton(int index) {
        if (commandsOn[index] != null)
            commandsOn[index].execute();
    }

    public void offButton(int index) {
        if (commandsOff[index] != null)
            commandsOff[index].execute();
    }
}

　　测试代码

public class Test {
    public static void main(String[] args) {
        RemoteController remoteController = new RemoteController();
        Light light = new Light();
        Radio radio = new Radio();
        remoteController.setCommand(0, new CommandOn(light), new CommandOff(light));
        remoteController.onButton(0);
        remoteController.offButton(0);
        remoteController.setCommand(0, new CommandOn(radio), new CommandOff(radio));
        remoteController.onButton(0);
        remoteController.offButton(0);
    }
}

　　如果你对这篇博客有什么建议或者疑问可以留言哦>V<