再次关于 Bridge 模式

Question

我正在尝试理解桥接模式。使用 Wiki 中的示例，一切正常。 但是如果我们有下一个设计呢：

如何实现不同的遥控器（例如红外线和 Wi-Fi）？我应该使用桥接模式以及如何使用？通过类比示例，我需要将所有方法与单个宽接口与硬件实现相结合，如下图所示。但我认为这不是一个好主意。

Answer 1

桥接模式很像适配器模式。

按照您的模型，假设您有一个 RemoteControl 抽象类：

public abstract class RemoteControl
{
      protected HadwareRemoteControl hardwareBridge;

      //Can be injected using DI
      public RemoteControl(HadwareRemoteControl hardwareBridge)
      {
           this.hardwareBridge= hardwareBridge;
      }

      public void on()
      {
           hardwareBridge.on();
      }

      public void off()
      {
           hardwareBridge.off();
      }
}

该类的两个实现：

public class TVRemoteControl extends RemoteControl
{
      public TVRemoteControl(TVHardwareRemoteControl hardwareBridge) {
           super(hardwareBridge);
      }

      public void nextChannel() {
           ((TVHardwareRemoteControl)hardwareBridge).nextChannel();
      }

      public void previousChannel() {
           ((TVHardwareRemoteControl)hardwareBridge).previousChannel();
      }
}

public class ModelRemoteControl extends RemoteControl
{
      public ModelRemoteControl (ModelHardwareRemoteControl hardwareBridge) {
           super(hardwareBridge);
      }

      public void moveForward() {
           ((ModelHardwareRemoteControl)hardwareBridge).moveForward();
      }

      public void moveBack() {
           ((ModelHardwareRemoteControl)hardwareBridge).moveBack();
      }     
}

现在，对于硬件桥接器，我们有一个基本接口：

public interface HadwareRemoteControl
{
      public void on();
      public void off();
}

还有两个接口：

public interface TVHadwareRemoteControl extends HardwareRemoteControl
{
      public void nextChannel();
      public void previousChannel();
}

public interface ModelHardwareRemoteControl extends HardwareRemoteControl
{
      public void moveForward();
      public void moveBack();
}

而且，就像在您的设计中一样，有两个实现：

public class InfraredRemoteControl implements TVHardwareRemoteControl, ModelHardwareRemoteControl
{
      public void on()
      {
         //Hardware Turn on
      }

      public void off()
      {
         //Hardware Turn off
      }

      public void nextChannel()
      {
         //Hardware Next channel
      }

      public void previousChannel()
      {
         //Hardware Previous channel
      }

      public void moveForward()
      {
         //Hardware Move Forward
      }

      public void moveBack()
      {
         //Hardware Move Back
      }
}


public class WifiRemoteControl implements TVHardwareRemoteControl, ModelHardwareRemoteControl
{
      public void on()
      {
         //Hardware Turn on
      }

      public void off()
      {
         //Hardware Turn off
      }

      public void nextChannel()
      {
         //Hardware Next channel
      }

      public void previousChannel()
      {
         //Hardware Previous channel
      }

      public void moveForward()
      {
         //Hardware Move Forward
      }

      public void moveBack()
      {
         //Hardware Move Back
      }
}

从外部项目中，您的 API 客户端可以更透明地使用硬件，甚至不知道这些实现：

TVRemoteControl tvRemote = Factory.CreateTVRemote();

//Depending on the injected hardware implementation, it may call InfraredRemoteControl or WifiRemoteControl
tvRemote.on();
tvRemote.nextChannel();