Android: excepción con el envío de ParcelFileDescriptor a través de Intent
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I am writing an android app where my service needs to send an image to some other apps (via a broadcast message or by starting a service - there a multiple apps that might be interested to receive the image).
If I load the image into an Bitmap object and put it as an "Extra" of an Intent it would actually work. However, I want to see if I can send a ParcelFileDescrptor around instead, and let the client load the Bitmap object on their own (from reading the spec, it looks like ParcelFileDescriptor is created just for this purpose - sharing files between processes). Here I am trying to avoid sending large objects via Intent. So I wrote something like this:
@Override
public int onStartCommand(Intent intent, int flags, int startId) {
System.out.println("Service is called" + this.getClass());
Intent newIntent = new Intent(MY_ACTION);
try {
File icon = new File(getExternalFilesDir(null), "robot_icon.jpg");
icon.setReadable(true, false);
if( !icon.exists() ) {
System.out.println("Writting file " + icon);
FileOutputStream out;
out = new FileOutputStream(icon);
BitmapFactory.decodeResource(getResources(), R.drawable.two_face_answer_map).compress(CompressFormat.JPEG, 100, out);
out.close();
System.out.println("Closing file after writing" + icon);
}
newIntent.putExtra(EXTRA_BITMAP, ParcelFileDescriptor.open(icon, ParcelFileDescriptor.MODE_READ_WRITE));
// sendBroadcast(newIntent);
startService(newIntent);
} catch (FileNotFoundException e) {
Log.e(TAG, "Error opening robot icon file", e);
}catch (IOException e) {
Log.e(TAG, "Error opening robot icon file", e);
}
System.out.println("No Exception");
return super.onStartCommand(intent, flags, startId);
}
When this code is executed, I always receive a RuntimeException that said "Not allowed to write file descriptor here". Please note that I see the problem both with sendBroadcast as well as startService options. Anybody knows why it is not allowed here? What did I do wrong? Did I misunderstand the ParcelFileDescriptor? Here is the trace:
01-01 08:06:02.589: E/AndroidRuntime(7483): FATAL EXCEPTION: main 01-01 08:06:02.589: E/AndroidRuntime(7483): java.lang.RuntimeException: Unable to start service com.test.robotsample.MyService@4161a0a8 with Intent { cmp=com.test.robotsample/.MyService }: java.lang.RuntimeException: Not allowed to write file descriptors here 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2507) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.app.ActivityThread.access$1900(ActivityThread.java:130) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1292) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.os.Handler.dispatchMessage(Handler.java:99) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.os.Looper.loop(Looper.java:137) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.app.ActivityThread.main(ActivityThread.java:4745) 01-01 08:06:02.589: E/AndroidRuntime(7483): at java.lang.reflect.Method.invokeNative(Native Method) 01-01 08:06:02.589: E/AndroidRuntime(7483): at java.lang.reflect.Method.invoke(Method.java:511) 01-01 08:06:02.589: E/AndroidRuntime(7483): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) 01-01 08:06:02.589: E/AndroidRuntime(7483): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) 01-01 08:06:02.589: E/AndroidRuntime(7483): at dalvik.system.NativeStart.main(Native Method) 01-01 08:06:02.589: E/AndroidRuntime(7483): Caused by: java.lang.RuntimeException: Not allowed to write file descriptors here 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.os.Parcel.nativeWriteFileDescriptor(Native Method) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.os.Parcel.writeFileDescriptor(Parcel.java:552) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.os.ParcelFileDescriptor.writeToParcel(ParcelFileDescriptor.java:412) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.os.Parcel.writeParcelable(Parcel.java:1254) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.os.Parcel.writeValue(Parcel.java:1173) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.os.Parcel.writeMapInternal(Parcel.java:591) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.os.Bundle.writeToParcel(Bundle.java:1619) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.os.Parcel.writeBundle(Parcel.java:605) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.content.Intent.writeToParcel(Intent.java:6470) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.app.ActivityManagerProxy.startService(ActivityManagerNative.java:2468) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.app.ContextImpl.startService(ContextImpl.java:1149) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.content.ContextWrapper.startService(ContextWrapper.java:383) 01-01 08:06:02.589: E/AndroidRuntime(7483): at com.test.robotsample.MyService.onStartCommand(MyService.java:63) 01-01 08:06:02.589: E/AndroidRuntime(7483): at android.app.ActivityThread.handleServiceArgs(ActivityThread.java:2490) 01-01 08:06:02.589: E/AndroidRuntime(7483): ...
1 Respuestas
4
Yes, it is not possible to pass a ParcelFileDescriptor through an Intent. Although this does not seem to be clearly documented in the Android docs.
Alternativas:
- use Bundle.putBinder() to pass a Binder which will return a Parcel with the PFD (from API 18).
- use a "bound service", started with Context.bindService(), where you again get a Binder through which to obtain the PFD.
contestado el 21 de mayo de 14 a las 07:05
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If I return PaecelFileDescriptor from a ContentProvider, it works just fine. So at least I think the problem should not be with the file (how and where it is stored and its permission...) it self. I just have to guess that ParcelFileDescriptor cannot be used in a broadcast or service Intent then. Just wish the spec was a bit clearer about it. - trungdinhtrong