意图过滤器没有要求的onReceive的USB_ACCESSORY_ATTACHED [英] Intent Filter not calling onReceive for USB_ACCESSORY_ATTACHED

问题描述

我已经在一个 MyDialogFragment 和注册/未注册它在构造函数中声明的意图过滤器 USB_ACCESSORY_ATTACHED 片段的 onResume 和的onPause 的方法。 MyReceiver 延伸的BroadcastReceiver 中的内部类接收 USB_ACCESSORY_ATTACHED 意图。请参见下面的code：

I have declared an intent filter for USB_ACCESSORY_ATTACHED in the constructor of a MyDialogFragment and registered/unregistered it in the fragment's onResume and onPause methods. MyReceiver extends BroadcastReceiver in an inner class to receive the USB_ACCESSORY_ATTACHED intent. See following code:

public class MyDialogFragment extends DialogFragment {

     private Context context;
     private IntentFilter usbIntentFilter;
     private MyReceiver myReceiver;

     MyDialogFragment(Context context) {
        usbIntentFilter = new IntentFilter(UsbManager.ACTION_USB_ACCESSORY_ATTACHED);
        myReceiver = new myReceiver();
        this.context = context;
     }


     @Override
     public void onResume() {
          super.onResume();

          // Register broadcast receiver
         context.registerReceiver(myReceiver, usbIntentFilter);
     }

     @Override
     public void onPause() {
          super.onPause();

          // Unregister broadcast receiver
          context.unregisterReceiver(myReceiver);
     }

     class MyReceiver extends BroadcastReceiver {

        @Override
        public void onReceive(Context context, Intent intent) {

            Log.d("MyApp","Called USB receiver");

        }
     }
}

不过， MyReceiver 的的onReceive 方法永远不会当我连接USB附件调用。此外，当我的意图变为

However, the onReceive method of MyReceiver never gets called when I attach a USB accessory. Furthermore, when I change the intent to

usbIntentFilter = new IntentFilter(UsbManager.ACTION_USB_ACCESSORY_DETACHED);

MyReceiver 的的onReceive 方法不会被调用。所以我的问题是：为什么当我拆下配件，而不是当我附上附件它的工作

the onReceive method of MyReceiver does get called. So my question is: why does it work when I detach the accessory, but not when I attach the accessory?

推荐答案

这样看来， USB_ACESSORY_ATTACHED 的意图从来没有真正得到过的活动，看到这么一个问题：

So it appears that USB_ACESSORY_ATTACHED intent never actually gets through to the activity, see SO question :

<一个href="http://stackoverflow.com/questions/6981736/android-3-1-usb-host-broadcastreceiver-does-not-receive-usb-device-attached/9814826#9814826">Android 3.1 USB主机 - 的BroadcastReceiver没有收到USB_DEVICE_ATTACHED

您必须使用 onResume 方法由 USB_ACCESSORY_ATTACHED 间接调用工作。我不得不说，这是不明确的Andr​​oid的文件中，我怀疑它的实现。

You have to work with the onResume method that is called indirectly by USB_ACCESSORY_ATTACHED. I have to say, this isn't clear in the Android documentation, and I question its implementation.

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