如何处理Flutter插件中Android TextToSpeech的DeadObjectException

问题 #

我开发的Flutter应用里，负责Android端文本转语音（TextToSpeech）功能的自定义插件出现崩溃：应用运行约30分钟后抛出以下异常：

android.os.DeadObjectException
  at android.os.BinderProxy.transactNative(Native Method)
  at android.os.BinderProxy.transact(BinderProxy.java:571)
  at android.speech.tts.ITextToSpeechService$Stub$Proxy.isLanguageAvailable(ITextToSpeechService.java:919)
  at android.speech.tts.TextToSpeech.lambda$isLanguageAvailable$16(TextToSpeech.java:1842)
  at android.speech.tts.TextToSpeech$$ExternalSyntheticLambda11.run(Unknown Source:2)
  at android.speech.tts.TextToSpeech$Connection.runAction(TextToSpeech.java:2361)
  at android.speech.tts.TextToSpeech.runAction(TextToSpeech.java:813)
  at android.speech.tts.TextToSpeech.runAction(TextToSpeech.java:803)
  at android.speech.tts.TextToSpeech.isLanguageAvailable(TextToSpeech.java:1825)
  at com.custom.my_audio_plugin.helpers.VoiceAssistant.isLanguageAvailable(VoiceAssistant.java:177)
  at com.custom.my_audio_plugin.MyAudioMapper.isLanguageAvailable(MyAudioMapper.java:358)
  at com.custom.my_audio_plugin.AudioMapperPlugin.onMethodCall(AudioMapperPlugin.java:150)
  at io.flutter.plugin.common.MethodChannel$IncomingMethodCallHandler.onMessage(MethodChannel.java:258)
  at io.flutter.embedding.engine.dart.DartMessenger.invokeHandler(DartMessenger.java:295)
  at io.flutter.embedding.engine.dart.DartMessenger.lambda$dispatchMessageToQueue$0$DartMessenger(DartMessenger.java:322)
  at io.flutter.embedding.engine.dart.-$$Lambda$DartMessenger$2j2MERcK825A5j1fv5sZ7xB2Iuo.run(Unknown Source:12)
  at android.os.Handler.handleCallback(Handler.java:938)
  at android.os.Handler.dispatchMessage(Handler.java:99)
  at android.os.Looper.loopOnce(Looper.java:201)
  at android.os.Looper.loop(Looper.java:288)
  at android.app.ActivityThread.main(ActivityThread.java:7839)
  at java.lang.reflect.Method.invoke(Native Method)
  at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:548)
  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1003)

已确认TtsEngine初始化正常，TextToSpeech.OnInitListener回调返回TextToSpeech.SUCCESS，且崩溃期间未调用ActivityAware.onDetachedFromActivity()与FlutterPlugin.onDetachedFromEngine()方法。崩溃后出现以下日志：

I/TextToSpeech(19748): Sucessfully bound to com.google.android.tts
I/TextToSpeech(19748): Connected to TTS engine
I/TextToSpeech(19748): Setting up the connection to TTS engine...

解决/处理指导 #

• 捕获异常并重建TTS实例：在调用isLanguageAvailable等TTS方法时，直接捕获DeadObjectException，一旦触发，立即销毁当前TextToSpeech实例并重新初始化。系统崩溃后已尝试重新绑定TTS引擎，但插件未主动处理实例重建，导致调用失效的Binder代理崩溃。
• 添加连接状态监听：注册TextToSpeech.OnConnectionListener，监听onConnectionSuspended和onConnectionFailed回调。当连接挂起或失败时，主动触发TTS实例重建，不要等到崩溃发生再处理。
• 优化实例生命周期管理：即使未收到页面或引擎解绑回调，Android系统可能因内存回收、TTS服务重启导致Binder连接失效。可以在每次调用TTS方法前验证实例状态，或定期通过轻量方法（如getDefaultVoice()）检查有效性，捕获异常后重建实例。
• 缓存语言可用性结果：如果插件频繁调用isLanguageAvailable，会增加TTS服务的依赖调用，加速连接异常。可以缓存首次查询的语言支持结果，无需每次都调用系统API。
• 备选TTS引擎支持：崩溃日志显示使用的是com.google.android.tts，部分设备上该服务可能因后台清理或版本问题重启。可以添加系统内置TTS引擎（如com.android.tts）作为备选，当默认引擎连接失效时自动切换。

内容的提问来源于stack exchange，提问作者Shahbaz Hashmi