/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License. You may obtain a copy of
* the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
* License for the specific language governing permissions and limitations under
* the License.
*/
package android.speech;
import android.annotation.SdkConstant;
import android.annotation.SdkConstant.SdkConstantType;
import android.app.Service;
import android.content.Intent;
import android.content.pm.PackageManager;
import android.os.Bundle;
import android.os.Handler;
import android.os.IBinder;
import android.os.Message;
import android.os.RemoteException;
import android.util.Log;
import java.lang.ref.WeakReference;
/**
* This class provides a base class for recognition service implementations. This class should be
* extended only in case you wish to implement a new speech recognizer. Please note that the
* implementation of this service is stateless.
*/
public abstract class RecognitionService extends Service {
/**
* The {@link Intent} that must be declared as handled by the service.
*/
@SdkConstant(SdkConstantType.SERVICE_ACTION)
public static final String SERVICE_INTERFACE = "android.speech.RecognitionService";
/**
* Name under which a RecognitionService component publishes information about itself.
* This meta-data should reference an XML resource containing a
* <code><{@link android.R.styleable#RecognitionService recognition-service}></code> tag.
*/
public static final String SERVICE_META_DATA = "android.speech";
/** Log messages identifier */
private static final String TAG = "RecognitionService";
/** Debugging flag */
private static final boolean DBG = false;
/** Binder of the recognition service */
private RecognitionServiceBinder mBinder = new RecognitionServiceBinder(this);
/**
* The current callback of an application that invoked the
* {@link RecognitionService#onStartListening(Intent, Callback)} method
*/
private Callback mCurrentCallback = null;
private static final int MSG_START_LISTENING = 1;
private static final int MSG_STOP_LISTENING = 2;
private static final int MSG_CANCEL = 3;
private static final int MSG_RESET = 4;
private final Handler mHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_START_LISTENING:
StartListeningArgs args = (StartListeningArgs) msg.obj;
dispatchStartListening(args.mIntent, args.mListener);
break;
case MSG_STOP_LISTENING:
dispatchStopListening((IRecognitionListener) msg.obj);
break;
case MSG_CANCEL:
dispatchCancel((IRecognitionListener) msg.obj);
break;
case MSG_RESET:
dispatchClearCallback();
break;
}
}
};
private void dispatchStartListening(Intent intent, final IRecognitionListener listener) {
if (mCurrentCallback == null) {
if (DBG) Log.d(TAG, "created new mCurrentCallback, listener = " + listener.asBinder());
try {
listener.asBinder().linkToDeath(new IBinder.DeathRecipient() {
@Override
public void binderDied() {
mHandler.sendMessage(mHandler.obtainMessage(MSG_CANCEL, listener));
}
}, 0);
} catch (RemoteException re) {
Log.e(TAG, "dead listener on startListening");
return;
}
mCurrentCallback = new Callback(listener);
RecognitionService.this.onStartListening(intent, mCurrentCallback);
} else {
try {
listener.onError(SpeechRecognizer.ERROR_RECOGNIZER_BUSY);
} catch (RemoteException e) {
Log.d(TAG, "onError call from startListening failed");
}
Log.i(TAG, "concurrent startListening received - ignoring this call");
}
}
private void dispatchStopListening(IRecognitionListener listener) {
try {
if (mCurrentCallback == null) {
listener.onError(SpeechRecognizer.ERROR_CLIENT);
Log.w(TAG, "stopListening called with no preceding startListening - ignoring");
} else if (mCurrentCallback.mListener.asBinder() != listener.asBinder()) {
listener.onError(SpeechRecognizer.ERROR_RECOGNIZER_BUSY);
Log.w(TAG, "stopListening called by other caller than startListening - ignoring");
} else { // the correct state
RecognitionService.this.onStopListening(mCurrentCallback);
}
} catch (RemoteException e) { // occurs if onError fails
Log.d(TAG, "onError call from stopListening failed");
}
}
private void dispatchCancel(IRecognitionListener listener) {
if (mCurrentCallback == null) {
if (DBG) Log.d(TAG, "cancel called with no preceding startListening - ignoring");
} else if (mCurrentCallback.mListener.asBinder() != listener.asBinder()) {
Log.w(TAG, "cancel called by client who did not call startListening - ignoring");
} else { // the correct state
RecognitionService.this.onCancel(mCurrentCallback);
mCurrentCallback = null;
if (DBG) Log.d(TAG, "canceling - setting mCurrentCallback to null");
}
}
private void dispatchClearCallback() {
mCurrentCallback = null;
}
private class StartListeningArgs {
public final Intent mIntent;
public final IRecognitionListener mListener;
public StartListeningArgs(Intent intent, IRecognitionListener listener) {
this.mIntent = intent;
this.mListener = listener;
}
}
/**
* Checks whether the caller has sufficient permissions
*
* @param listener to send the error message to in case of error
* @return {@code true} if the caller has enough permissions, {@code false} otherwise
*/
private boolean checkPermissions(IRecognitionListener listener) {
if (DBG) Log.d(TAG, "checkPermissions");
if (RecognitionService.this.checkCallingOrSelfPermission(android.Manifest.permission.
RECORD_AUDIO) == PackageManager.PERMISSION_GRANTED) {
return true;
}
try {
Log.e(TAG, "call for recognition service without RECORD_AUDIO permissions");
listener.onError(SpeechRecognizer.ERROR_INSUFFICIENT_PERMISSIONS);
} catch (RemoteException re) {
Log.e(TAG, "sending ERROR_INSUFFICIENT_PERMISSIONS message failed", re);
}
return false;
}
/**
* Notifies the service that it should start listening for speech.
*
* @param recognizerIntent contains parameters for the recognition to be performed. The intent
* may also contain optional extras, see {@link RecognizerIntent}. If these values are
* not set explicitly, default values should be used by the recognizer.
* @param listener that will receive the service's callbacks
*/
protected abstract void onStartListening(Intent recognizerIntent, Callback listener);
/**
* Notifies the service that it should cancel the speech recognition.
*/
protected abstract void onCancel(Callback listener);
/**
* Notifies the service that it should stop listening for speech. Speech captured so far should
* be recognized as if the user had stopped speaking at this point. This method is only called
* if the application calls it explicitly.
*/
protected abstract void onStopListening(Callback listener);
@Override
public final IBinder onBind(final Intent intent) {
if (DBG) Log.d(TAG, "onBind, intent=" + intent);
return mBinder;
}
@Override
public void onDestroy() {
if (DBG) Log.d(TAG, "onDestroy");
mCurrentCallback = null;
mBinder.clearReference();
super.onDestroy();
}
/**
* This class receives callbacks from the speech recognition service and forwards them to the
* user. An instance of this class is passed to the
* {@link RecognitionService#onStartListening(Intent, Callback)} method. Recognizers may call
* these methods on any thread.
*/
public class Callback {
private final IRecognitionListener mListener;
private Callback(IRecognitionListener listener) {
mListener = listener;
}
/**
* The service should call this method when the user has started to speak.
*/
public void beginningOfSpeech() throws RemoteException {
if (DBG) Log.d(TAG, "beginningOfSpeech");
mListener.onBeginningOfSpeech();
}
/**
* The service should call this method when sound has been received. The purpose of this
* function is to allow giving feedback to the user regarding the captured audio.
*
* @param buffer a buffer containing a sequence of big-endian 16-bit integers representing a
* single channel audio stream. The sample rate is implementation dependent.
*/
public void bufferReceived(byte[] buffer) throws RemoteException {
mListener.onBufferReceived(buffer);
}
/**
* The service should call this method after the user stops speaking.
*/
public void endOfSpeech() throws RemoteException {
mListener.onEndOfSpeech();
}
/**
* The service should call this method when a network or recognition error occurred.
*
* @param error code is defined in {@link SpeechRecognizer}
*/
public void error(int error) throws RemoteException {
Message.obtain(mHandler, MSG_RESET).sendToTarget();
mListener.onError(error);
}
/**
* The service should call this method when partial recognition results are available. This
* method can be called at any time between {@link #beginningOfSpeech()} and
* {@link #results(Bundle)} when partial results are ready. This method may be called zero,
* one or multiple times for each call to {@link SpeechRecognizer#startListening(Intent)},
* depending on the speech recognition service implementation.
*
* @param partialResults the returned results. To retrieve the results in
* ArrayList<String> format use {@link Bundle#getStringArrayList(String)} with
* {@link SpeechRecognizer#RESULTS_RECOGNITION} as a parameter
*/
public void partialResults(Bundle partialResults) throws RemoteException {
mListener.onPartialResults(partialResults);
}
/**
* The service should call this method when the endpointer is ready for the user to start
* speaking.
*
* @param params parameters set by the recognition service. Reserved for future use.
*/
public void readyForSpeech(Bundle params) throws RemoteException {
mListener.onReadyForSpeech(params);
}
/**
* The service should call this method when recognition results are ready.
*
* @param results the recognition results. To retrieve the results in {@code
* ArrayList<String>} format use {@link Bundle#getStringArrayList(String)} with
* {@link SpeechRecognizer#RESULTS_RECOGNITION} as a parameter
*/
public void results(Bundle results) throws RemoteException {
Message.obtain(mHandler, MSG_RESET).sendToTarget();
mListener.onResults(results);
}
/**
* The service should call this method when the sound level in the audio stream has changed.
* There is no guarantee that this method will be called.
*
* @param rmsdB the new RMS dB value
*/
public void rmsChanged(float rmsdB) throws RemoteException {
mListener.onRmsChanged(rmsdB);
}
}
/** Binder of the recognition service */
private static final class RecognitionServiceBinder extends IRecognitionService.Stub {
private final WeakReference<RecognitionService> mServiceRef;
public RecognitionServiceBinder(RecognitionService service) {
mServiceRef = new WeakReference<RecognitionService>(service);
}
@Override
public void startListening(Intent recognizerIntent, IRecognitionListener listener) {
if (DBG) Log.d(TAG, "startListening called by:" + listener.asBinder());
final RecognitionService service = mServiceRef.get();
if (service != null && service.checkPermissions(listener)) {
service.mHandler.sendMessage(Message.obtain(service.mHandler,
MSG_START_LISTENING, service.new StartListeningArgs(
recognizerIntent, listener)));
}
}
@Override
public void stopListening(IRecognitionListener listener) {
if (DBG) Log.d(TAG, "stopListening called by:" + listener.asBinder());
final RecognitionService service = mServiceRef.get();
if (service != null && service.checkPermissions(listener)) {
service.mHandler.sendMessage(Message.obtain(service.mHandler,
MSG_STOP_LISTENING, listener));
}
}
@Override
public void cancel(IRecognitionListener listener) {
if (DBG) Log.d(TAG, "cancel called by:" + listener.asBinder());
final RecognitionService service = mServiceRef.get();
if (service != null && service.checkPermissions(listener)) {
service.mHandler.sendMessage(Message.obtain(service.mHandler,
MSG_CANCEL, listener));
}
}
public void clearReference() {
mServiceRef.clear();
}
}
}
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