命令接口：

public interface Command {
   public void execute();
}

 

　　接收者接口：

public interface Light {
   public void on();

   public void off();
}

public interface Door {
   public void open();

   public void close();
}

 

　　接收者：

public class LivingRoomLight implements Light{
   public void on(){
      System.out.println("LivingRoomLight light on.");
}
   public void off(){
      System.out.println("LivingRoomLight light off.");
}
}

public class KitchenLight implements Light{
   public void on(){
      System.out.println("KitchenLight light on.");
}
   public void off(){
      System.out.println("KitchenLight light off.");
}
}

public class GarageDoor implements Door{
   public void open(){
      System.out.println("This door is open");
}
   public void close(){
      System.out.println("This door is closed");
}
}

 

　　调用者：

public class SimpleRemoteControl {
   Command slot;
   public  SimpleRemoteControl(){}

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

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

 

　　客户端：

使用lambda表达式可以省去具体的命令者类的创建。

在setCommand时候，直接传入接口Command的execute的具体实现，execute的具体实现通过lambda表达式和接收者的动作完成。

事实上，具体创建的命令者，也就是重写了Command的execute接口。

public class RemoteControlTest {
   public static void main(String[] args){

      SimpleRemoteControl remote = new SimpleRemoteControl();
　　　　LivingRoomLight livingRoomLight = new LivingRoomLight();
　　　　remote.setCommand(()->livingRoomLight.on());
　　　　remote.buttonWasPressed();

　　　　KitchenLight kitchenLight = new KitchenLight();
　　　　remote.setCommand(()->kitchenLight.on());
　　　　remote.buttonWasPressed();

　　　　GarageDoor garageDoor = new GarageDoor();
　　　　remote.setCommand(()->garageDoor.open());
　　　　remote.buttonWasPressed();
}
}

 

测试结果：

LivingRoomLight light on.

KitchenLight light on.

This door is open