Android 关闭JobService中的TextToSpeech对象时偶尔发生崩溃

我使用JobService实现的TTS（文本到语音）如下所示：

package services;

import android.annotation.TargetApi;
import android.app.job.JobParameters;
import android.app.job.JobService;
import android.content.Intent;
import android.os.Build;
import android.speech.tts.TextToSpeech;

import utilities.PhoneUtils;

@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public class TTSJobScheduledService extends JobService {

private static TextToSpeech voice =null;

public static TextToSpeech getVoice() {
    return voice;
}

@Override
public boolean onStartJob(JobParameters params) {
    startTTSEngine();
    PhoneUtils.scheduleTTSJob(getApplicationContext()); // reschedule the job
    return true;
}

@Override
public boolean onStopJob(JobParameters params) {
    clearTtsEngine();
    return true;
}

private void startTTSEngine()
{
    try{
        voice = new TextToSpeech(TTSJobScheduledService.this, new TextToSpeech.OnInitListener() {
            @Override
            public void onInit(final int status) {

            }
        });
    }
    catch(Exception e){
        e.printStackTrace();
    }
}

private static void clearTtsEngine()
{
    if(voice!=null)
    {
        voice.stop();
        voice.shutdown();
        voice = null;
    }
}
}

Caused by java.lang.IllegalArgumentException: Service not registered: android.speech.tts.TextToSpeech$Connection@2b329ed
   at android.app.LoadedApk.forgetServiceDispatcher(LoadedApk.java:1659)
   at android.app.ContextImpl.unbindService(ContextImpl.java:1854)
   at android.content.ContextWrapper.unbindService(ContextWrapper.java:703)
   at android.speech.tts.TextToSpeech$Connection.disconnect(TextToSpeech.java:2287)
   at android.speech.tts.TextToSpeech$1.run(TextToSpeech.java:855)
   at android.speech.tts.TextToSpeech$1.run(TextToSpeech.java:851)
   at android.speech.tts.TextToSpeech$Connection.runAction(TextToSpeech.java:2307)
   at android.speech.tts.TextToSpeech.runAction(TextToSpeech.java:752)
   at android.speech.tts.TextToSpeech.runActionNoReconnect(TextToSpeech.java:738)
   at android.speech.tts.TextToSpeech.shutdown(TextToSpeech.java:850)
   at services.TTSJobScheduledService.clearTtsEngine(Unknown Source:11)
   at services.TTSJobScheduledService.onStopJob(Unknown Source)
   at android.app.job.JobService$1.onStopJob(JobService.java:76)
   at android.app.job.JobServiceEngine$JobHandler.handleMessage(JobServiceEngine.java:117)
   at android.os.Handler.dispatchMessage(Handler.java:109)
   at android.os.Looper.loop(Looper.java:166)
   at android.app.ActivityThread.main(ActivityThread.java:7377)
   at java.lang.reflect.Method.invoke(Method.java)
   at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:469)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:963)

在一些华为设备上，它导致了如下崩溃：

package services;

import android.annotation.TargetApi;
import android.app.job.JobParameters;
import android.app.job.JobService;
import android.content.Intent;
import android.os.Build;
import android.speech.tts.TextToSpeech;

import utilities.PhoneUtils;

@TargetApi(Build.VERSION_CODES.LOLLIPOP)
public class TTSJobScheduledService extends JobService {

private static TextToSpeech voice =null;

public static TextToSpeech getVoice() {
    return voice;
}

@Override
public boolean onStartJob(JobParameters params) {
    startTTSEngine();
    PhoneUtils.scheduleTTSJob(getApplicationContext()); // reschedule the job
    return true;
}

@Override
public boolean onStopJob(JobParameters params) {
    clearTtsEngine();
    return true;
}

private void startTTSEngine()
{
    try{
        voice = new TextToSpeech(TTSJobScheduledService.this, new TextToSpeech.OnInitListener() {
            @Override
            public void onInit(final int status) {

            }
        });
    }
    catch(Exception e){
        e.printStackTrace();
    }
}

private static void clearTtsEngine()
{
    if(voice!=null)
    {
        voice.stop();
        voice.shutdown();
        voice = null;
    }
}
}

Caused by java.lang.IllegalArgumentException: Service not registered: android.speech.tts.TextToSpeech$Connection@2b329ed
   at android.app.LoadedApk.forgetServiceDispatcher(LoadedApk.java:1659)
   at android.app.ContextImpl.unbindService(ContextImpl.java:1854)
   at android.content.ContextWrapper.unbindService(ContextWrapper.java:703)
   at android.speech.tts.TextToSpeech$Connection.disconnect(TextToSpeech.java:2287)
   at android.speech.tts.TextToSpeech$1.run(TextToSpeech.java:855)
   at android.speech.tts.TextToSpeech$1.run(TextToSpeech.java:851)
   at android.speech.tts.TextToSpeech$Connection.runAction(TextToSpeech.java:2307)
   at android.speech.tts.TextToSpeech.runAction(TextToSpeech.java:752)
   at android.speech.tts.TextToSpeech.runActionNoReconnect(TextToSpeech.java:738)
   at android.speech.tts.TextToSpeech.shutdown(TextToSpeech.java:850)
   at services.TTSJobScheduledService.clearTtsEngine(Unknown Source:11)
   at services.TTSJobScheduledService.onStopJob(Unknown Source)
   at android.app.job.JobService$1.onStopJob(JobService.java:76)
   at android.app.job.JobServiceEngine$JobHandler.handleMessage(JobServiceEngine.java:117)
   at android.os.Handler.dispatchMessage(Handler.java:109)
   at android.os.Looper.loop(Looper.java:166)
   at android.app.ActivityThread.main(ActivityThread.java:7377)
   at java.lang.reflect.Method.invoke(Method.java)
   at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:469)
   at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:963)

据我所知，它正试图清除一项可能已经清除的服务。但是，我不确定在这种情况下如何正确实现CleartSengine方法。有人能告诉我哪里出了问题以及如何解决吗