Headfirst java设计模式-命令模式

命令模式：将请求封装成对象，以便使用不同的请求、队列或者日志来参数化其他对象。命令模式也支持可撤销的操作。
简而言之：命令模式就是将方法调用封装起来。

相关代码：
(1)先定义一个command接口：

public interface Command {
    public void execute();
}

(2)定义一个Light类作为command执行者（receiver）

public class Light {
    String location = null;

    public Light(String location) {
        this.location = location;
    }

    public void on() {
        System.out.println(location + " Turn light on.");
    }

    public void off() {
        System.out.println(location + " Turn light off.");
    }
}

(3)继承command接口，定义一个command类，采用组合方式将相关的操作传递给实际执行者

public class LightOnCommand implements Command{

    Light light;

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

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

(4)创建一个command调用者

public class SimpleRemoteControl {
    Command slot;

    public void setCommand(Command command) {
        this.slot = command;
    }

    public void buttonWasPressed() {
        slot.execute();
    }
}

(4)测试代码

public class RemoteControlTest {
    public static void main(String[] args) {
        SimpleRemoteControl remote = new SimpleRemoteControl();
        Light light = new Light("Living room");
        LightOnCommand lightOn = new LightOnCommand(light);

    remote.setCommand(lightOn);
    remote.buttonWasPressed();  
    }
}

(5)测试结果
Living room Turn light on.