Android下如何使用硬键盘快捷键。

我们在Windows下常常有一些快捷键来启动某个应用的需求，同样在我们的Android系统下也可以实现这样的作用。

比如按下CAMERA键，来启动Camera应用。

使用步骤如下，

  1 先定义好CAMEAR键值，比如KEYCODE_CAMERA=27并要在xxx_Keypad.kl定义好扫描码与CAMERA对应的关系

 如 key 212   CAMERA

  2 定义相关BROADCAST_INTENT_ACTION @Intent.java

  @SdkConstant(SdkConstantType.BROADCAST_INTENT_ACTION)    public static final String ACTION_CAMERA_BUTTON = "android.intent.action.CAMERA_BUTTON";  

3 在系统文件PhoneWindow.java中有onKeyDown（）函数来捕获CAMERA键值并发送相关intent.

  case KeyEvent.KEYCODE_CAMERA: {

   ....

 // Broadcast an intent that the Camera button was longpressed                    Intent intent = new Intent(Intent.ACTION_CAMERA_BUTTON, null);                    intent.putExtra(Intent.EXTRA_KEY_EVENT, event);                    getContext().sendOrderedBroadcast(intent, null);

       }

4 在camera应用下如果要接收这个Broadcast消息，需要在AndroidManifest.xml中增加receive 相关的intent-filter.

  <receiver android:name="CameraButtonIntentReceiver">   <intent-filter>    <action android:name="android.intent.action.CAMERA_BUTTON" />   </intent-filter>  </receiver>

 

5 定义类CameraButtonIntentReceiver 并重载onReceive方法来启动CameraActivity

public class CameraButtonIntentReceiver extends BroadcastReceiver {    public CameraButtonIntentReceiver() {    }         @Override    public void onReceive(Context context, Intent intent) {        // Try to get the camera hardware        CameraHolder holder = CameraHolder.instance();        if (holder.tryOpen() == null) return;

        // We are going to launch the camera, so hold the camera for later use        holder.keep();        holder.release();        Intent i = new Intent(Intent.ACTION_MAIN);        i.setClass(context, Camera.class);        i.addCategory("android.intent.category.LAUNCHER");        i.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);        context.startActivity(i);    }   }