我创建了一个非常基本的服务，用于使用TTS播放字典（请参见下面的完整代码），并且在我的所有3个android设备（android版本）上都遇到了相同的问题5、7和8）。
要点： 该应用会播放词汇表条目，定义和示例。在每个应用之间，应用都会暂停。
症状：
当我使用8秒钟的暂停时间并且该应用处于后台模式（屏幕关闭）时，问题大多发生了。播放只会冻结。
有时播放会继续自己的，并在长时间暂停后关闭屏幕，有时长达20-30分钟甚至更长（，但随后播放下一个条目如果我们还没有激活屏幕，也可以在很长的暂停之后进行。可能还有其他过程会部分唤醒电话吗？
此外，在按电源按钮并打开屏幕后，播放将继续进行。
调试信息：
我估计应用程序被冻结后会在Visual Studio中按下暂停键，以查看是哪段代码引起的-不幸的是，调试器似乎使设备保持清醒状态，这个问题很难揭示< / strong>。
为了防止我的应用程序被冻结，我在服务中获得了 Partial WakeLock （但这仍然无济于事，即使应用程序清单包含对WAKE_LOCK的许可） >
private void AcquireWakeLock(MainActivity activity)
{
var mgr = (PowerManager)activity.ApplicationContext.GetSystemService(Context.PowerService);
WakeLock = mgr.NewWakeLock(WakeLockFlags.Partial, "myWakeLock");
WakeLock.Acquire();
}
我的应用程序还具有“播放/暂停”按钮，我使用TaskCompletionSource来使应用程序等待直到恢复播放
public async Task PlayPause(bool isChecked, MainActivity mainActivity)
{
if (isChecked)
{
ReleaseWakeLock();
AppSuspended = new TaskCompletionSource<bool>();
Tts.Stop();
}
else
{
AcquireWakeLock(mainActivity);
AppSuspended.TrySetResult(true);
}
}
然后，在即将播放下一个单词/词组之前，我将以下代码用于我的应用，以等待恢复播放
await AppSuspended.Task;
完整代码
[Service(Name = "com.my_app.service.PlaybackService")]
public class PlaybackService : Service, TextToSpeech.IOnInitListener, TextToSpeech.IOnUtteranceCompletedListener
{
public IBinder Binder { get; private set; }
private Java.Util.Locale Lang;
private bool Playing;
private int EntryIndex;
private int DefinitionIndex;
private DictionaryDto Dictionary;
private EntryDto CurrentEntry;
private DefinitionDto CurrentDefinition;
private TaskCompletionSource<bool> AppSuspended;
protected TextToSpeech Tts;
private TaskCompletionSource<bool> PlaybackFinished;
private WakeLock WakeLock;
public override void OnCreate()
{
base.OnCreate();
Tts = new TextToSpeech(this, this);
Lang = Tts.DefaultLanguage;
AppSuspended = new TaskCompletionSource<bool>();
AppSuspended.TrySetResult(true);
}
public override IBinder OnBind(Intent intent)
{
Binder = new PlaybackBinder(this);
return Binder;
}
public override bool OnUnbind(Intent intent)
{
return base.OnUnbind(intent);
}
public override void OnDestroy()
{
Binder = null;
base.OnDestroy();
}
void TextToSpeech.IOnUtteranceCompletedListener.OnUtteranceCompleted(string utteranceId)
{
if (utteranceId.Equals("PlaybackFinished")) { PlaybackFinished.TrySetResult(true); }
}
void TextToSpeech.IOnInitListener.OnInit(OperationResult status)
{
// if we get an error, default to the default language
if (status == OperationResult.Error)
Tts.SetLanguage(Java.Util.Locale.Default);
// if the listener is ok, set the lang
if (status == OperationResult.Success)
{
Tts.SetLanguage(Lang);
Tts.SetOnUtteranceCompletedListener(this);
}
}
public async Task Play(string text)
{
Dictionary<string, string> myHashRender = new Dictionary<string, string>();
myHashRender.Add(TextToSpeech.Engine.KeyParamUtteranceId, "PlaybackFinished");
PlaybackFinished = new TaskCompletionSource<bool>();
Tts.Speak(text, QueueMode.Flush, myHashRender);
await PlaybackFinished.Task;
}
public async Task PlaySilence(long ms)
{
Dictionary<string, string> myHashRender = new Dictionary<string, string>();
myHashRender.Add(TextToSpeech.Engine.KeyParamUtteranceId, "PlaybackFinished");
PlaybackFinished = new TaskCompletionSource<bool>();
Tts.PlaySilence(ms, QueueMode.Flush, myHashRender);
await PlaybackFinished.Task;
}
private async Task PlayDictionary(MainActivity activity)
{
EntryIndex = 0;
for (; EntryIndex < Dictionary.Entries.Count;)
{
CurrentEntry = Dictionary.Entries.ElementAt(EntryIndex);
await AppSuspended.Task;
if (!Playing) { return; }
if (!string.IsNullOrEmpty(CurrentEntry.Text))
{
await AppSuspended.Task;
if (!Playing) { return; }
await Play(CurrentEntry.Text);
}
DefinitionIndex = 0;
for (; DefinitionIndex < CurrentEntry.Definitions.Count();)
{
CurrentDefinition = CurrentEntry.Definitions.ElementAt(DefinitionIndex);
await PlayDefinition();
await PlayExamples();
DefinitionIndex++;
}
if (Playing)
{
DefinitionIndex++;
}
EntryIndex++;
}
}
private async Task PlayExamples()
{
if (!Playing) { return; }
foreach (var example in CurrentDefinition.Examples)
{
if (!string.IsNullOrEmpty(example))
{
await AppSuspended.Task;
if (!Playing) { return; }
await Play(example);
if (Playing)
{
await PlaySilence((long)TimeSpan.FromSeconds(8).TotalMilliseconds);
}
}
}
}
private async Task PlayDefinition()
{
if (!Playing) { return; }
if (!string.IsNullOrEmpty(CurrentEntry.Definitions.ElementAt(DefinitionIndex).Text))
{
await AppSuspended.Task;
if (!Playing) { return; }
await PlayDefinitionText();
if (Playing)
{
await PlaySilence((long)TimeSpan.FromSeconds(7).TotalMilliseconds);
}
}
}
private async Task PlayDefinitionText()
{
await AppSuspended.Task;
await Play($"{CurrentEntry.Definitions.ElementAt(DefinitionIndex).Text}");
}
private void ReleaseWakeLock()
{
if (WakeLock != null)
{
WakeLock.Release();
}
}
private void AcquireWakeLock(MainActivity activity)
{
var mgr = (PowerManager)activity.ApplicationContext.GetSystemService(Context.PowerService);
WakeLock = mgr.NewWakeLock(WakeLockFlags.Partial, "myWakeLock");
WakeLock.Acquire();
}
public async Task PlayPause(bool isChecked, MainActivity mainActivity)
{
if (isChecked)
{
ReleaseWakeLock();
AppSuspended = new TaskCompletionSource<bool>();
Tts.Stop();
}
else
{
AcquireWakeLock(mainActivity);
AppSuspended.TrySetResult(true);
}
}
}
其他信息：
问题在我所有的设备上发生
答案 0 :(得分：0)
我对问题进行了彻底调查，并按照建议改用前台服务，这完美地解决了我的问题。
使用棒棒糖，牛轧糖，奥利奥进行了测试。
将以下方法放在您的MainActivity类中
public void StartForegroundServiceSafely(Intent intent)
{
if (Android.OS.Build.VERSION.SdkInt >= Android.OS.BuildVersionCodes.O)
{
StartForegroundService(intent);
}
else
{
StartService(intent);
}
}
然后您通过Intent
public void PlayFromFile(Android.Net.Uri uri)
{
AcquireWakeLock();
Intent startIntent = new Intent(this, typeof(PlaybackService));
startIntent.SetAction(PlaybackConsts.Start);
startIntent.PutExtra("uri", uri.ToString());
StartForegroundServiceSafely(startIntent);
}
在您的服务中实施OnStartCommand方法
public class PlaybackService : Service, TextToSpeech.IOnInitListener, TextToSpeech.IOnUtteranceCompletedListener
[return: GeneratedEnum]
public override StartCommandResult OnStartCommand(Intent intent, [GeneratedEnum] StartCommandFlags flags, int startId)
{
if (intent.Action.Equals(PlaybackConsts.Start))
{
var notification =
new Notification.Builder(this)
.SetContentTitle(Resources.GetString(Resource.String.ApplicationName))
.SetContentText("HELLO WORLD")
.SetOngoing(true)
.Build();
StartForeground(SERVICE_RUNNING_NOTIFICATION_ID, notification);
}
if (intent.Action.Equals(PlaybackConsts.Start))
{
var uri = Android.Net.Uri.Parse(intent.GetStringExtra("uri"));
var content = MiscellaneousHelper.GetTextFromStream(ContentResolver.OpenInputStream(uri));
Dictionary = DictionaryFactory.Get(content);
Playing = true;
Task.Factory.StartNew(async () =>
{
await PlayDictionary();
});
}
if (intent.Action.Equals(PlaybackConsts.PlayPause))
{
bool isChecked = intent.GetBooleanExtra("isChecked", false);
PlayPause(isChecked);
}
if (intent.Action.Equals(PlaybackConsts.NextEntry))
{
NextEntry();
}
if (intent.Action.Equals(PlaybackConsts.PrevEntry))
{
PrevEntry();
}
if (intent.Action.Equals(PlaybackConsts.Stop))
{
Task.Factory.StartNew(async () =>
{
await Stop();
});
StopForeground(true);
StopSelf();
}
return StartCommandResult.Sticky;
}
从上面的代码中，我们学习了如何通过OnStartCommand方法触发服务的功能。
定义您的BroadcastReceiver
[BroadcastReceiver(Enabled = true, Exported = false)]
public class PlaybackBroadcastReceiver : BroadcastReceiver
{
public override void OnReceive(Context context, Intent intent)
{
var activity = MainActivity.GetInstance(); // if you need your activity here, see further code below
if (intent.Action == "renderEntry")
{
string entryHtml = intent.GetStringExtra("html");
// omitting code to keep example concise
}
}
}
在您的MainActivity类中声明接收方字段。
还可以在BroadcastReceiver类中进行活动，可以声明GetInstance方法（单例方法）。
public class MainActivity : AppCompatActivity
{
PlaybackBroadcastReceiver receiver;
protected DrawerLayout drawerLayout;
protected NavigationView navigationView;
protected WakeLock WakeLock;
private static MainActivity instance;
public static MainActivity GetInstance()
{
return instance;
}
protected override void OnCreate(Bundle bundle)
{
base.OnCreate(bundle);
receiver = new PlaybackBroadcastReceiver();
instance = this;
}
protected override void OnStart()
{
base.OnStart();
RegisterReceiver(receiver, new IntentFilter("renderEntry"));
}
要取消注册接收者，请使用以下行：
UnregisterReceiver(receiver);
广播来自服务的事件
在服务中，您还必须使用意图
private void SendRenderEntryBroadcast(EntryDto entry)
{
Intent intent = new Intent("renderEntry");
intent.PutExtra("html", GetEntryHtml(entry));
SendBroadcast(intent);
}