Develop Reference

Why is Android file creation suddenly failing when it worked on Android 11 previously?

In the last few days, my Android app is suddenly failing to download files from a web server to store in the app. This is the same for all users I have contacted. It was previously working in Android 11, so it's something that has only just changed. It's a (free) niche app for UK glider pilots to process NOTAMS, and has relatively large number of users who I don't want to let down.
The published app uses getExternalFilesDir(null) to return the directory in which to store the downloaded files, with android:requestLegacyExternalStorage set to "true" in the manifest.
I changed getExternalFilesDir(null) to getFilesDir() in Android Studio since that's what I understand should now be used for internal app data files. This returns /data/user/0/(my package name)/files. I'm running the Pixel 2 API 30 emulator for debugging, and the File Explorer shows that /data/data/(my package name)/files directory has been created. Everything I've read on here says that this is what is supposed to happen and it should all work. However no file was created when I attempted the download.
I changed android:requestLegacyExternalStorage to "false", and this time a file was created as expected. However it was empty and the download thread was giving an exception "unexpected end of stream on com.android.okhttp.Address#89599f3f".
This is the relevant code in my DownloadFile class which runs as a separate thread (comments removed for compactness):
public class DownloadFile implements Runnable
{
private String mUrlString;
private String mFileName;
private CountDownLatch mLatch;
public DownloadFile(String urlString, String fileName, CountDownLatch latch)
{
mUrlString = urlString;
mFileName = fileName;
mLatch = latch;
}
public void run()
{
HttpURLConnection urlConnection = null;
// Note for StackOverflow: following is a public static variable defined in the main activity
Spine.mDownloadStatus = false;
try
{
URL url = new URL(mUrlString);
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setRequestMethod("GET");
urlConnection.setDoOutput(true);
urlConnection.setUseCaches(false);
urlConnection.connect();
File file = new File(Spine.dataDir, mFileName);
FileOutputStream fileOutput = new FileOutputStream(file);
InputStream inputStream = urlConnection.getInputStream();
byte[] buffer = new byte[1024];
int bufferLength = 0; // used to store a temporary size of the buffer
while ((bufferLength = inputStream.read(buffer)) > 0)
{
fileOutput.write(buffer, 0, bufferLength);
}
fileOutput.close();
Spine.mDownloadStatus = true;
}
// catch some possible errors...
catch (IOException e)
{
Spine.mErrorString = e.getMessage();
}
if (urlConnection != null)
urlConnection.disconnect();
// Signal completion
mLatch.countDown();
}
}
I now believe the problem lies with the URL connection, rather than the changes to local file storage access which is what I first thought. Incidentally, if I enter the full URL into my web browser the complete text file is displayed OK, so it's not a problem with the server.

The problem has been narrowed down to changes to the functionality of the website that hosts the data files to be downloaded. It's been made https secure and they are currently working on further changes.
I temporarily moved the hosting to my own website in Android Studio and everything worked so it's down to those website changes and nothing to do with my code (at least it may need changing later to support the upgrade to the main hosting site).
Thanks to all for responding.

How to play cached byte array in android

I have a Xamarin application which plays remote(internet) audio files using the MediaPlayer with the following setup:
_mediaPlayer.SetDataSource(mediaUri);
_mediaPlayer.PrepareAsync();
Now I would like to change the implementation to also cache files. For the caching part I found a really nice library called MonkeyCache which saves the files in this JSON format:
{"$type":"System.Byte[], mscorlib","$value":"UklGRhAoAgBXQVZFZm10IBAAAAABAAIARKwAABCxAgAEABAAZGF0YdAnAgAAAAAAAAAAAAAAAAAA+P/4/+z/7P8KAAoA7//v//L/8v8JAAkA6f/p//j/+P8FAAUA6P/o/wEAAQD+//7/5//n ................."}
So my MediaPlayer setup has now changed to:
if (Barrel.Current.Exists(mediaUri)){
var audio = Barrel.Current.Get<byte[]>(mediaUri);
_mediaPlayer.SetDataSource(???);
}else{
using (var webClient = new WebClient()){
var downloadDataBytes = webClient.DownloadData(mediaUri);
if (downloadDataBytes != null && downloadDataBytes.Length > 0)
{
Barrel.Current.Add(mediaUri, downloadDataBytes, TimeSpan.FromDays(1));
_mediaPlayer.SetDataSource(???);
}
}
}
I would like to play the audio from a byte[] instead of the mediaUri.
Is there any way to actually play an in memory byte[]?
The only solutions that I could find were to create a FileInputStream out of a File by using a filepath, but the implementation of the MonkeyCache actually hashes the file name, before adding it:
static string Hash(string input){
var md5Hasher = MD5.Create();
var data = md5Hasher.ComputeHash(Encoding.Default.GetBytes(input));
return BitConverter.ToString(data);
}
Therefore the downloaded bytes, will be saved under:
/data/data/com.package.name.example/cache/com.package.name.example/MonkeyCacheFS/81-D6-E8-62-F3-4D-F1-64-A6-A1-53-46-34-1E-FE-D1
Even if I were to use the same hashing logic to actually compute the file path myself and use the FileInputStream which might be working by what I've read, it would defeat the purpose of using the var audio = Barrel.Current.Get<byte[]>(mediaUri); functionality of the MonkeyCache.
However, if that is the only way, I will do it.
Edit: Even with my described approach, it would probably not work right away as even if I compute the right file name, it is still in JSON format.
Edit2: A working solution is:
var audio = Barrel.Current.Get<byte[]>(mediaUri);
var url = "data:audio/mp3;base64," + Convert.ToBase64String(audio);
_mediaPlayer.SetDataSource(url);

Finally figured it out:
The MediaPlayer.SetDataSource method has an overload which expects a MediaDataSource object.
MediaDataSource
For supplying media data to the framework. Implement
this if your app has special requirements for the way media data is
obtained
Therefore, you can use your implementation of the MediaDataSource and feed it your byte array.
public class StreamMediaDataSource : MediaDataSource
{
private byte[] _data;
public StreamMediaDataSource(byte[] data)
{
_data = data;
}
public override long Size
=> _data.Length;
public override void Close()
{
_data = null;
}
public override int ReadAt(long position, byte[] buffer, int offset, int size)
{
if (position >= _data.Length)
{
return -1;
}
if (position + size > _data.Length)
{
size -= (Convert.ToInt32(position) + size) - _data.Length;
}
Array.Copy(_data, position, buffer, offset, size);
return size;
}
}
which will lead to the MediaPlayer data source to be
_mediaPlayer.SetDataSource(new StreamMediaDataSource(downloadedDataBytes));
Edit: This only works for API >= 23. I still have to find a solution for API<23(which I still haven't).
Edit2: For API < 23 support I used the
var url = $"data:audio;base64,{Convert.ToBase64String(downloadedDataBytes)}";
_mediaPlayer.SetDataSource(url);
approach.

Picasso RequestHandler - Decrypt file before load image

All my images are encrypted in Android file system. When I need to show them, I need to decrypt, generate the bitmap and then delete the file. I'm trying to use Picasso to load my images. I created an RequestHandler to decrypt and load image.
RequestHandler accepts two types of result:
1. the bitmap or 2. a stream.
I'm trying to return the stream. That way Picasso can load images using the best practices, prevent out of memory. I created an custom Stream class and override the Dispose() method to delete the decrypted file after use.
The problem is: The stream is not disposing, neither closing, after the image is loaded, and I can't for automatic dispose by GAC (I'm using Xamarin/C#). Any ideas? What can I do?
UPDATE (19/01/17): I found out a small bug in my code and after fixing it, my problem was solved. But here is my custom RequestHandler for future reference... EncryptedFileStream is my custom stream that wraps the original stream and delete the decrypted file on Dispose().
public class EncryptedFilenameRequestHandler : RequestHandler
{
private readonly Context _context;
private readonly ICriptoService _criptoService;
public EncryptedFilenameRequestHandler(Context context, ICriptoService criptoService)
{
if (context == null) throw new ArgumentNullException(nameof(context));
if (criptoService == null) throw new ArgumentNullException(nameof(criptoService));
_context = context;
_criptoService = criptoService;
}
public override bool CanHandleRequest(Request request)
{
var uri = request.Uri;
return string.Compare(uri.Scheme, Constantes.AppSchema, true) == 0 &&
string.Compare(uri.Authority, Constantes.Host, true) == 0 &&
string.Compare(uri.Path, "/loadimagem/filename/encrypted", true) == 0;
}
public override Result Load(Request request, int networkPolicy)
{
string password = request.Uri.GetQueryParameter("p");
string encryptedFilename = request.Uri.GetQueryParameter("f");
string decryptedFilename = System.IO.Path.Combine(AppEnviroment.GetTempDirectory(), Guid.NewGuid().ToString("N"));
if (string.IsNullOrWhiteSpace(encryptedFilename) || !File.Exists(encryptedFilename))
return null;
_criptoService.Decrypt(encryptedFilename, decryptedFilename, password);
//retorna um stream para leitura do arquivo descriptografado
var uri = Android.Net.Uri.FromFile(new Java.IO.File(decryptedFilename));
var stream = new EncryptedFileStream(decryptedFilename, _context.ContentResolver.OpenInputStream(uri));
return new Result(stream, Picasso.LoadedFrom.Disk);
}
}

I found out a small bug in my code and, after fixing it, my problem was solved. The code for EncryptedFilenameRequestHandler posted in the question is working without any problem.

Load image from binary base64

EDIT: This is a bug in Android version <4.3 Kitkat. It relates to the libjpeg library in Android, which can't handle JPEGs with missing EOF/EOI bits, or apparently with metadata/EXIF data that it doesn't like.
https://code.google.com/p/android/issues/detail?id=9064
ORIGINAL QUESTION:
I have an issue when loading an image in my app.
My endpoint sends JSON which contains a BASE64 encoded image. Depending on the REST call, these images can be PNG or JPG. Some of the JPG files suffer from an issue where they are missing an EOF bit at the end. The PNG files work, and some JPG files work, but unfortunately a lot of these JPG files with the issue are present in the Oracle DB (stored as BLOB). I don't have control of the DB.
I have been looking through Google bugs here:
https://code.google.com/p/android/issues/detail?id=9064
and here:
https://code.google.com/p/android/issues/detail?id=57502
The issue is also seen where the encoding is CYMK using a custom ICC profile.
Decoding the image the standard way returns false:
byte[] imageAsBytes = Base64.decode(base64ImageString, Base64.DEFAULT);
return BitmapFactory.decodeByteArray(imageAsBytes, 0, imageAsBytes.length);
According to the bug reports above, the built in JPG parser in Android is to blame.
I'm trying to figure out a workaround for my device, which is stuck on 4.2.2. I have no other option on this OS version.
I thought it might be a good idea to try and use an image loader library like Universal Image Loader, but it requires I either have the image stored locally, or stored on a URL. As I get the data in BASE64 from the REST server, I can't use this. An option is to support decodeByteArray in a custom class that extends BaseImageDecoder, as stated by the dev at the bottom here: https://github.com/nostra13/Android-Universal-Image-Loader/issues/209
Here's where I get stuck. I already have a custom image decoder to try handle the issue of the missing EOF marker in the JPG file, but I don't know how to edit it to add support for decodeByteArray.
Here is my CustomImageDecoder:
public class CustomImageDecoder extends BaseImageDecoder {
public CustomImageDecoder(boolean loggingEnabled) {
super(loggingEnabled);
}
#Override
protected InputStream getImageStream(ImageDecodingInfo decodingInfo) throws IOException {
InputStream stream = decodingInfo.getDownloader()
.getStream(decodingInfo.getImageUri(), decodingInfo.getExtraForDownloader());
return stream == null ? null : new JpegClosedInputStream(stream);
}
private class JpegClosedInputStream extends InputStream {
private static final int JPEG_EOI_1 = 0xFF;
private static final int JPEG_EOI_2 = 0xD9;
private final InputStream inputStream;
private int bytesPastEnd;
private JpegClosedInputStream(final InputStream iInputStream) {
inputStream = iInputStream;
bytesPastEnd = 0;
}
#Override
public int read() throws IOException {
int buffer = inputStream.read();
if (buffer == -1) {
if (bytesPastEnd > 0) {
buffer = JPEG_EOI_2;
} else {
++bytesPastEnd;
buffer = JPEG_EOI_1;
}
}
return buffer;
}
}
}
By the way, using the above custom class, I am trying to load my byte array like this:
byte[] bytes = Base64.decode(formattedB64String, Base64.NO_WRAP);
ByteArrayInputStream is = new ByteArrayInputStream(bytes);
String imageId = "stream://" + is.hashCode();
...
ImageLoader imageLoader = ImageLoader.getInstance();
imageLoader.displayImage(imageId, userImage, options);
and I get this error:
ImageLoader: Image can't be decoded [stream://1097215584_656x383]
Universal Image loader does not allow the stream:// schema, so I created a custom BaseImageDownloader class that allows it:
public class StreamImageDownloader extends BaseImageDownloader {
private static final String SCHEME_STREAM = "stream";
private static final String STREAM_URI_PREFIX = SCHEME_STREAM + "://";
public StreamImageDownloader(Context context) {
super(context);
}
#Override
protected InputStream getStreamFromOtherSource(String imageUri, Object extra) throws IOException {
if (imageUri.startsWith(STREAM_URI_PREFIX)) {
return (InputStream) extra;
} else {
return super.getStreamFromOtherSource(imageUri, extra);
}
}
}
So if anyone can help me create a better CustomImageDecoder that handles a BASE64 encoded string, or a byte[] containing an image so I can use decodeByteArray, I would be grateful!
Thank you.

UnversalImageLoader uses the following schemes to decode the files
"h t t p ://site.com/image.png" // from Web
"file:///mnt/sdcard/image.png" // from SD card
"file:///mnt/sdcard/video.mp4" // from SD card (video thumbnail)
"content://media/external/images/media/13" // from content provider
"content://media/external/video/media/13" // from content provider (video thumbnail)
"assets://image.png" // from assets
"drawable://" + R.drawable.img // from drawables (non-9patch images)
your scheme is stream://
Hope that helps.

Just to close this off:
The issue here is actually a bug in Android <4.3 where Android can't display images that either aren't closed properly (missing end bytes) or contain certain metadata that, for some reason, it doesn't like. I'm not sure what metadata this is, however. My issue was with JPEGs not being terminated properly.
The bug is fixed in Android 4.3 anyway.

Phonegap/Cordova - download jpg to local FS on Windows Phone 8/8.1

I have been trying to download an image from an url to local file system using cordova 3.8 on Windows Phone.
I want to store pictures and be able to use them in the HTML view.
I am using the file transfer and the file system plugins :
https://github.com/apache/cordova-plugin-file-transfer
http://docs.phonegap.com/en/edge/cordova_file_file.md.html
I have been playing around with both, but without success. I think the problem comes from the target file URI, as I have not found any way of getting the download folder path.
I can easily read and write text files using the examples in the cordova-file plugin's documentation, but I do not find anything on how to get the directory's path in order to pass it to the file transfer plugin.
Any idea ? I am testing on WP8.

You can make your own plugin(I can explain how if needed) and use MediaLibrary.SavePicture method. Put this in your plugin class:
public static byte[] ReadFully(Stream input)
{
byte[] buffer = new byte[16 * 1024];
using (MemoryStream ms = new MemoryStream())
{
int read;
while ((read = input.Read(buffer, 0, buffer.Length)) > 0)
{
ms.Write(buffer, 0, read);
}
return ms.ToArray();
}
}
public void SavePicture(string options)
{
string[] optString = getOptionStrings(options);
string url = optString[0];
string callbackId = optString[1];
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.BeginGetResponse(new AsyncCallback((result) =>
{
try
{
HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(result);
byte[] content = ReadFully(response.GetResponseStream());
MediaLibrary lib = new MediaLibrary();
lib.SavePicture("Test Picture", content);
DispatchCommandResult(new PluginResult(PluginResult.Status.OK), callbackId);
}
catch (Exception e)
{
DispatchCommandResult(new PluginResult(PluginResult.Status.ERROR, e), callbackId);
}
}), null);
}
And call it like this:
cordova.exec(function (result) {
// success
}, function (e) {
// error
}, 'YourPluginClass', 'SavePicture', [yourUrl]);
NOTE: You must have ID_CAP_MEDIALIB_PHOTO capability checked in the manifest.