TextToSpeech的UtteranceProgressListener触发问题

最近在写一个安卓语音识别的项目，结果助教要求将其中的dialog变成voice dialog，也就是首先要把dialog的内容读出来，然后让用户说"yes"或者"no"触发相应的操作。本来不是很难，只需要在tts的callback中的onDone方法触发新的语音识别即可，但是遇到了一点小问题让我debug了两天。

首先上代码，这是tts的类

public class SpeechForDialog {
TextToSpeech tts;
protected Context context;
protected String words="";

public SpeechForDialog(Context c,String s){
this.context=c;
this.words=s;
initSpeech();
}

private void initSpeech(){
tts=new TextToSpeech(context.getApplicationContext(), new ttsInitListener());
}

private class ttsInitListener implements TextToSpeech.OnInitListener {
@Override
public void onInit(int status) {
if (status == TextToSpeech.SUCCESS) {
if (tts!=null&&!tts.isSpeaking()) {
CharSequence cs=words;
tts.setLanguage(Locale.US);
tts.setOnUtteranceProgressListener(new ttsUtteranceListener());
tts.speak(cs, TextToSpeech.QUEUE_FLUSH, null, null);
}
}
else if(status == TextToSpeech.ERROR){
tts = null;
Toast.makeText(context,"Error",Toast.LENGTH_SHORT).show();
}
}
}

private class ttsUtteranceListener extends UtteranceProgressListener{
@Override
public void onStart(String utteranceId) {

}
@Override
public void onDone(String utteranceId) {
Toast.makeText(a, "toast", Toast.LENGTH_SHORT).show();

}
@Override
public void onError(String utteranceId) {

}
}

}

然后在MainActivity里使用 ：

new SpeechForDialog(this,"this is the text to speech test");

结果发现，尽管"this is the text to speech test"确实能读出来，但是onDone方法里的Toast并没有弹出。

原因是，speak方法有四个参数

public int speak (CharSequence text, int queueMode, Bundle params, String utteranceId)

再看UtteranceProgressListener的说明：

Listener for events relating to the progress of an utterance through the synthesis queue. Each utterance is associated with a call to speak(CharSequence, int, Bundle, String) or synthesizeToFile(CharSequence, Bundle, File, String) with an associated utterance
identifier, as per KEY_PARAM_UTTERANCE_ID. The callbacks specified in this method can be called from multiple threads.

这表示UtteranceProgressListener需要一个id，但我在使用speak的时候第四个参数设置成了null，导致UtteranceProgressListener没法触发，所以把代码

tts.speak(cs, TextToSpeech.QUEUE_FLUSH, null, null);

修改为

tts.speak(cs, TextToSpeech.QUEUE_FLUSH, null, "UniqueID");

理论上应该没问题了。为啥是理论上呢？因为这样改完Toast依然没有触发。继续修改，将onDone方法改为如下：

@Override
public void onDone(String utteranceId) {
final Activity a=(Activity)context;
a.runOnUiThread(new Runnable() {
public void
4000
run() {
Toast.makeText(a, "kkkk", Toast.LENGTH_SHORT).show();
}
});
}

关于toast和thread的关系就不在这里细说了，总之修改完成后，toast就可以触发了！