无法让Android语音识别器开始收听

Question

我创建了一个Android语音识别服务，能够从意图开始服务，但无法让语音识别器开始收听语音命令。

以下是我的代码：

MainActivity：

@Override
protected void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    Intent i= new Intent(getApplicationContext(), MyService.class);
    // potentially add data to the intent
    i.putExtra("KEY1", "Value to be used by the service");
    getApplicationContext().startService(i);

}

服务代码：

public void onCreate()
    {
        super.onCreate();
        mAudioManager = (AudioManager) getSystemService(Context.AUDIO_SERVICE); 
        mSpeechRecognizer = SpeechRecognizer.createSpeechRecognizer(this);
        mSpeechRecognizer.setRecognitionListener(new SpeechRecognitionListener());
        mSpeechRecognizerIntent = new Intent(RecognizerIntent.ACTION_RECOGNIZE_SPEECH);
        mSpeechRecognizerIntent.putExtra(RecognizerIntent.EXTRA_LANGUAGE_MODEL,
                                         RecognizerIntent.LANGUAGE_MODEL_FREE_FORM);
        mSpeechRecognizerIntent.putExtra(RecognizerIntent.EXTRA_CALLING_PACKAGE,
                                         this.getPackageName());

    }


protected class IncomingHandler extends Handler
{
    private WeakReference<MyService> mtarget;

    IncomingHandler(MyService target)
    {
        mtarget = new WeakReference<MyService>(target);
    }


    @Override
    public void handleMessage(Message msg)
    {
        final MyService target = mtarget.get();

        switch (msg.what)
        {
            case MSG_RECOGNIZER_START_LISTENING:

                if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)
                {
                    // turn off beep sound  
                    if (!mIsStreamSolo)
                    {
                        mAudioManager.setStreamSolo(AudioManager.STREAM_VOICE_CALL, true);
                        mIsStreamSolo = true;
                    }
                }
                 if (!target.mIsListening)
                 {
                     target.mSpeechRecognizer.startListening(target.mSpeechRecognizerIntent);
                     target.mIsListening = true;
                    //Log.d(TAG, "message start listening"); //$NON-NLS-1$
                 }
                 break;

             case MSG_RECOGNIZER_CANCEL:
                if (mIsStreamSolo)
               {
                    mAudioManager.setStreamSolo(AudioManager.STREAM_VOICE_CALL, false);
                    mIsStreamSolo = false;
               }
                  target.mSpeechRecognizer.cancel();
                  target.mIsListening = false;
                  //Log.d(TAG, "message canceled recognizer"); //$NON-NLS-1$
                  break;
         }
   } 
} 

// Count down timer for Jelly Bean work around
protected CountDownTimer mNoSpeechCountDown = new CountDownTimer(5000, 5000)
{

    @Override
    public void onTick(long millisUntilFinished)
    {
        // TODO Auto-generated method stub

    }

    @Override
    public void onFinish()
    {
        mIsCountDownOn = false;
        Message message = Message.obtain(null, MSG_RECOGNIZER_CANCEL);
        try
        {
            mServerMessenger.send(message);
            message = Message.obtain(null, MSG_RECOGNIZER_START_LISTENING);
            mServerMessenger.send(message);
        }
        catch (RemoteException e)
        {

        }
    }
};

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

    if (mIsCountDownOn)
    {
        mNoSpeechCountDown.cancel();
    }
    if (mSpeechRecognizer != null)
    {
        mSpeechRecognizer.destroy();
    }
}

protected class SpeechRecognitionListener implements RecognitionListener
{

    @Override
    public void onBeginningOfSpeech()
    {
        // speech input will be processed, so there is no need for count down anymore
        if (mIsCountDownOn)
        {
            mIsCountDownOn = false;
            mNoSpeechCountDown.cancel();
        }               
        //Log.d(TAG, "onBeginingOfSpeech"); //$NON-NLS-1$
    }

    @Override
    public void onBufferReceived(byte[] buffer)
    {

    }

    @Override
    public void onEndOfSpeech()
    {
        //Log.d(TAG, "onEndOfSpeech"); //$NON-NLS-1$
     }

    @Override
    public void onError(int error)
    {
        if (mIsCountDownOn)
        {
            mIsCountDownOn = false;
            mNoSpeechCountDown.cancel();
        }
         mIsListening = false;
         Message message = Message.obtain(null, MSG_RECOGNIZER_START_LISTENING);
         try
         {
                mServerMessenger.send(message);
         }
         catch (RemoteException e)
         {

         }
        //Log.d(TAG, "error = " + error); //$NON-NLS-1$
    }

    @Override
    public void onEvent(int eventType, Bundle params)
    {

    }

    @Override
    public void onPartialResults(Bundle partialResults)
    {

    }

    @Override
    public void onReadyForSpeech(Bundle params)
    {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN)
        {
            mIsCountDownOn = true;
            mNoSpeechCountDown.start();

        }
        //Log.d(TAG, "onReadyForSpeech"); //$NON-NLS-1$
    }

    @Override
    public void onResults(Bundle results)
    {
        //Log.d(TAG, "onResults"); //$NON-NLS-1$

    }

    @Override
    public void onRmsChanged(float rmsdB)
    {

    }


}

有人可以指出出错的地方吗？任何帮助将不胜感激：）