getToken（）提供异常

Question

protected override void OnHandleIntent(Intent intent)
{
    try
    {
        Log.Info("RegistrationIntentService", "Calling InstanceID.GetToken");
        lock (locker)
        {
            var instanceID = InstanceID.GetInstance(Application.Context);


            var token =  instanceID.GetToken(
                "<Project number>", GoogleCloudMessaging.InstanceIdScope, null);// exception occurred at this line 

            Log.Info("RegistrationIntentService", "GCM Registration Token: " + token);
            SendRegistrationToAppServer(token);
            Subscribe(token);
        }
    }
    catch (Exception e)
    {
        Log.Debug("RegistrationIntentService", "Failed to get a registration token");
        return;
    }
}

{java.io.ioException:SERVICE_NOT_AVAILABLE at system.runtime.exceptionservices.exceptiondispatchinfo.throw()[0x0000c]in/src/mono.android/src/runtime/jnienv.g.cs:195 at android.gms.gcm.iid.instanceId.getToken(system.string authorizedEntity,system.string scope,android.os.bundle extras）[0x00096]in：0 at leaveapplication.droid.registrationintentservice.onhandleintent(android.content.intent)[0x0003a]in在com.google.android.gms.iid.zzc.zzb（联合国com.google.android.gms.iid.zzc.zza（未知来源）com.google.android.gms.iid.instanceid.zzc（未知来源）com.google.android.gms.instanceid.zzc（未知来源）com.google.android.gms.instanceid.zzc（未知来源）com.google.android.gms.instanceid.zzc（未知来源）com.google.android.gms.instanceid.gettoken（未知来源）在Android.os.handler.dispatchMessage（handler.java：65）在Android.os.handler.dispatchMessage（handler.java：102）在Android.os.looper.loop（looper.java：135）在Android.os.handlerthread.run（handlerthread.java：61）}

我的android Manifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.yourcompany.LeaveApplication" android:installLocation="auto"
          android:versionCode="1"
    android:versionName="1.0">
  <uses-sdk android:minSdkVersion="15" />
  <application android:label="XamarinLeaveApp"></application>
  <uses-permission android:name="com.google.android.c2dm.permission.RECEIVE" />
  <uses-permission android:name="android.permission.WAKE_LOCK" />
  <uses-permission android:name="android.permission.INTERNET" />
  <uses-permission android:name="com.yourcompany.LeaveApplication.permission.C2D_MESSAGE" />
  <permission android:name="com.yourcompany.LeaveApplication.permission.C2D_MESSAGE"
              android:protectionLevel="signature" />
  <receiver android:name="com.google.android.gms.gcm.GcmReceiver"
               android:exported="true"
               android:permission="com.google.android.c2dm.permission.SEND">
    <intent-filter>
      <action android:name="com.google.android.c2dm.intent.RECEIVE" />
      <action android:name="com.google.android.c2dm.intent.REGISTRATION" />
      <category android:name="com.yourcompany.LeaveApplication" />
    </intent-filter>
  </receiver>
</manifest>

Answer 1

service_not_available是库的有效错误：

设备无法读取响应，或者存在服务器错误。应用程序以后应该使用指数退避和重试重试请求（在每次后续失败时，增加重试前的延迟）。

当then library由于设备条件（通常没有连接/无法到达google服务器）或其他服务器问题而无法获得令牌时，就会发生此错误。
在这种情况下，您有责任实现重试逻辑。