Create and Share a File from Internal Storage
android, android-contentprovider, android-file
Solution
It is possible to expose a file stored in your apps private directory via a ContentProvider. Here is some example code I made showing how to create a content provider that can do this.
Manifest
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.providertest"
android:versionCode="1"
android:versionName="1.0">
<uses-sdk android:minSdkVersion="11" android:targetSdkVersion="15" />
<application android:label="@string/app_name"
android:icon="@drawable/ic_launcher"
android:theme="@style/AppTheme">
<activity
android:name=".MainActivity"
android:label="@string/app_name">
<intent-filter>
<action android:name="android.intent.action.MAIN" />
<category android:name="android.intent.category.LAUNCHER" />
</intent-filter>
</activity>
<provider
android:name="MyProvider"
android:authorities="com.example.prov"
android:exported="true"
/>
</application>
</manifest>
In your ContentProvider override openFile to return the ParcelFileDescriptor
@Override
public ParcelFileDescriptor openFile(Uri uri, String mode) throws FileNotFoundException {
File cacheDir = getContext().getCacheDir();
File privateFile = new File(cacheDir, "file.xml");
return ParcelFileDescriptor.open(privateFile, ParcelFileDescriptor.MODE_READ_ONLY);
}
Make sure you have copied your xml file to the cache directory
private void copyFileToInternal() {
try {
InputStream is = getAssets().open("file.xml");
File cacheDir = getCacheDir();
File outFile = new File(cacheDir, "file.xml");
OutputStream os = new FileOutputStream(outFile.getAbsolutePath());
byte[] buff = new byte[1024];
int len;
while ((len = is.read(buff)) > 0) {
os.write(buff, 0, len);
}
os.flush();
os.close();
is.close();
} catch (IOException e) {
e.printStackTrace(); // TODO: should close streams properly here
}
}
Now any other apps should be able to get an InputStream for your private file by using the content uri (content://com.example.prov/myfile.xml)
For a simple test, call the content provider from a seperate app similar to the following
private class MyTask extends AsyncTask<String, Integer, String> {
@Override
protected String doInBackground(String... params) {
Uri uri = Uri.parse("content://com.example.prov/myfile.xml");
InputStream is = null;
StringBuilder result = new StringBuilder();
try {
is = getApplicationContext().getContentResolver().openInputStream(uri);
BufferedReader r = new BufferedReader(new InputStreamReader(is));
String line;
while ((line = r.readLine()) != null) {
result.append(line);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} finally {
try { if (is != null) is.close(); } catch (IOException e) { }
}
return result.toString();
}
@Override
protected void onPostExecute(String result) {
Toast.makeText(CallerActivity.this, result, Toast.LENGTH_LONG).show();
super.onPostExecute(result);
}
}
Problem
My goal is to create a XML file on internal storage and then send it through the share Intent. I'm able to create a XML file using this code ``` FileOutputStream outputStream = context.openFileOutput(fileName, Context.MODE_WORLD_READABLE); PrintStream printStream = new PrintStream(outputStream); String xml = this.writeXml(); // get XML here printStream.println(xml); printStream.close(); ``` I'm stuck trying to retrieve a Uri to the output file in order to share it. I first tried to access the file by converting the file to a Uri ``` File outFile = context.getFileStreamPath(fileName); return Uri.fromFile(outFile); ``` This returns file:///data/data/com.my.package/files/myfile.xml but I cannot appear to attach this to an email, upload, etc. If I manually check the file length, it's proper and shows there is a reasonable file size. Next I created a content provider and tried to reference the file and it isn't a valid handle to the file. The `ContentProvider` doesn't ever seem to be called a any point. ``` Uri uri = Uri.parse("content://" + CachedFileProvider.AUTHORITY + "/" + fileName); return uri; ``` This returns content://com.my.package.provider/myfile.xml but I check the file and it's zero length. How do I access files properly? Do I need to create the file with the content provider? If so, how? Update Here is the code I'm using to share. If I select Gmail, it does show as an attachment but when I send it gives an error Couldn't show attachment and the email that arrives has no attachment. ``` public void onClick(View view) { Log.d(TAG, "onClick " + view.getId()); switch (view.getId()) { case R.id.share_cancel: setResult(RESULT_CANCELED, getIntent()); finish(); break; case R.id.share_share: MyXml xml = new MyXml(); Uri uri; try { uri = xml.writeXmlToFile(getApplicationContext(), "myfile.xml"); //uri is "file:///data/data/com.my.package/files/myfile.xml" Log.d(TAG, "Share URI: " + uri.toString() + " path: " + uri.getPath()); File f = new File(uri.getPath()); Log.d(TAG, "File length: " + f.length()); // shows a valid file size Intent shareIntent = new Intent(); shareIntent.setAction(Intent.ACTION_SEND); shareIntent.putExtra(Intent.EXTRA_STREAM, uri); shareIntent.setType("text/plain"); startActivity(Intent.createChooser(shareIntent, "Share")); } catch (FileNotFoundException e) { e.printStackTrace(); } break; } } ``` I noticed that there is an `Exception` thrown here from inside createChooser(...), but I can't figure out why it's thrown. E/ActivityThread(572): Activity com.android.internal.app.ChooserActivity has leaked IntentReceiver com.android.internal.app.ResolverActivity$1@4148d658 that was originally registered here. Are you missing a call to unregisterReceiver()? I've researched this error and can't find anything obvious. Both of these links suggest that I need to unregister a receiver. - ChooserActivity has leaked IntentReceiver - Why does Intent.createChooser() need a BroadcastReceiver and how to implement? I have a receiver setup, but it's for an `AlarmManager` that is set elsewhere and doesn't require the app to register / unregister. Code for openFile(...) In case it's needed, here is the content provider I've created. ``` public ParcelFileDescriptor openFile(Uri uri, String mode) throws FileNotFoundException { String fileLocation = getContext().getCacheDir() + "/" + uri.getLastPathSegment(); ParcelFileDescriptor pfd = ParcelFileDescriptor.open(new File(fileLocation), ParcelFileDescriptor.MODE_READ_ONLY); return pfd; } ```