Develop Reference

How to create a shared folder usable by my android app?

I've got a question that probably borders on opinion, but I've not any related questions or documentation that answers, so I feel like it's a fair one to ask.
I'm trying to build an android app which modifies music files, and what I'd like to do is have a shared folder so that the files and the results can be accessible and shared. I'd like it if it was among the other folders like Music, Downloads, Movies, etc, or even under Music since it's music related. However this seems like it's a security no no in Android, as after I've made something and put it in there I have to use an intent to access it again, where as I'd rather just be able to open the files and not have a permissions based fiasco. Maybe some type of symbolic link like in Linux that pointed to my apps internal folder could be used, but of this I'm still uncertain.
In any case, is there a way I should go about this? If so, are there some resources I could be pointed to?
Thank you in advance to anyone who takes this up!
Edit for CommonsWare:
I used the following to create the folder:
File mediaStorageDir = new File(Environment.getExternalStorageDirectory(), APP_NAME);
And this to copy files from elsewhere to there:
public void copyFileToHomeDirectory(Uri uri)
{
try
{
ContentResolver contentResolver = getApplicationContext().getContentResolver();
String fileName = queryName(contentResolver, uri);
//Get file extension
String fileType = fileName.substring(fileName.length() - 4, fileName.length());
if(fileType.equalsIgnoreCase(MP3_EXTENSION))
{
String path = Environment.getExternalStorageDirectory() + APP_FOLDER;
InputStream in = contentResolver.openInputStream(uri);
File outputFile = new File(path + File.separator + fileName);
outputFile.createNewFile();
OutputStream out = new FileOutputStream(outputFile);
//First we crack open the file to copy it's contents:
byte[] buffer = new byte[KB_SIZE];
int read;
while ((read = in.read(buffer)) != -1)
{
out.write(buffer, 0, read);
}
in.close();
in = null;
// write the output file (You have now copied the file)
out.flush();
out.close();
out = null;
}
}
catch(FileNotFoundException fnfe)
{
Log.e(TAG, "FileNotFoundException");
Log.e(TAG, Log.getStackTraceString(fnfe));
}
catch(IOException ioe)
{
Log.e(TAG, "IOException");
Log.e(TAG, Log.getStackTraceString(ioe));
}
catch(Exception e)
{
Log.e(TAG, "General Exception");
Log.e(TAG, Log.getStackTraceString(e));
}
}
I've tried other methods that I've overwritten in the process, but accessing the files to be used again I need something like this:
public void openDirectory(View view)
{
// Choose a directory using the system's file picker.
Intent intent = new Intent(Intent.ACTION_GET_CONTENT);
// Provide read access to files and sub-directories in the user-selected
// directory.
//intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
//intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
//intent.addCategory(Intent.CATEGORY_OPENABLE);
// Optionally, specify a URI for the directory that should be opened in
// the system file picker when it loads.
//intent.putExtra(DocumentsContract.EXTRA_INITIAL_URI, uriToLoad);
intent.putExtra(Intent.EXTRA_ALLOW_MULTIPLE, true);
intent.addCategory(Intent.CATEGORY_OPENABLE);
intent.setType("*/*"); //use image/* for photos, etc.
//The result of this code will be calling the onActivityResult function below
startActivityForResult(intent, REQUEST_MUSIC_DIR);
}
Edit2:
I've reorganized the folders to what I think I should be doing so that I can work with the files freely, however, even in my internal cache storage (getCacheDir() + folder_name) either isn't letting me create the files (outputFile.createNewFile doesn't throw an error) or it isn't letting me open them when I go to get a directory listing.
Here's my code for creating the file:
String path = getCacheDir() + MY_SUB_FOLDER;
//uri is obtained through ACTION_OPEN_DOCUMENT intent
InputStream in = contentResolver.openInputStream(uri);
File outputFile = new File(path + "/" + fileName);
outputFile.createNewFile();
Log.i(TAG, "The new file's directory/path is: " + outputFile.getAbsolutePath());
//NOTE: This is returning /data/user/0/com.example.myapplication/cache/MY_SUB_FOLDER/file_name.mp3
OutputStream out = new FileOutputStream(outputFile);
byte[] buffer = new byte[1024];
int read;
while ((read = in.read(buffer)) != -1)
{
out.write(buffer, 0, read);
}
in.close();
in = null;
out.flush();
out.close();
out = null;
This is my code for attempting to open and read these newly created files
File directory = new File(getCacheDir(), MY_SUB_FOLDER);
Log.i(TAG, "This is the directory we're trying to get the files from: " + directory.getAbsolutePath());
//NOTE: This returns /data/user/0/com.example.myapplication/cache/MY_SUB_FOLDER
File[] files = directory.listFiles();
if(files != null)
{
for(int i = 0; i < files.length; i++)
{
Log.d(TAG, "Files found: " + files[i].getAbsolutePath());
}
}
The files variable isn't null but it's length is 0 and no files are found.
Edit3:
I am catching the exceptions and logging any stack traces, which currently returns nothing.
catch(FileNotFoundException fnfe)
{
Log.i(TAG, "FileNotFoundException");
Log.i(TAG, Log.getStackTraceString(fnfe));
}
catch(IOException ioe)
{
Log.i(TAG, "IOException");
Log.i(TAG, Log.getStackTraceString(ioe));
}
catch(Exception e)
{
Log.i(TAG, "General Exception");
Log.i(TAG, Log.getStackTraceString(e));
}

Download APK from url and execute

I'm using the DownloadManager to download the apk from url. Download completes, I get the onReceive in my BroadcastReceiver for DownloadManager.ACTION_DOWNLOAD_COMPLETE.
Some Coding: I download the apk file from an url to the download directory.
DownloadManager.Request r = new DownloadManager.Request(mUri);
r.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "myapp.apk");
r.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
DownloadManager dm = (DownloadManager) activity.getSystemService(Context.DOWNLOAD_SERVICE);
SharedPreferences mSharedPref = activity.getSharedPreferences("package", Context.MODE_PRIVATE);
mSharedPref.edit().putLong("downloadID", dm.enqueue(r)).commit();
onReceive
File apkFile = new File(Environment.DIRECTORY_DOWNLOADS + "myapp.apk");
Intent promptInstall = new Intent(Intent.ACTION_VIEW).setDataAndType(Uri.fromFile(apkFile), "application/vnd.android.package-archive");
startActivity(promptInstall);
Problems:
The file is there, I want to execute it but I package-installer is not shown
Even though I see the file in my phones download folder, I if I want to install it there is no package-installer to choose
I'm not sure if I do the file and pathing stuff right..
I get an parsing error from android when I try to open the file
Someone got an idea please?

I recently had to do something like this, hope it helps:
EDIT: Couple of notes,
apkurl is a string to the download location.
Make the byte buffer big enough for your response
try {
String PATH = Environment.getExternalStorageDirectory() + "/download/";
File file = new File(PATH);
file.mkdirs();
// Create a file on the external storage under download
File outputFile = new File(file, "app.apk");
FileOutputStream fos = new FileOutputStream(outputFile);
HttpGet m_httpGet = null;
HttpResponse m_httpResponse = null;
// Create a http client with the parameters
HttpClient m_httpClient = setupHttpClient();
String result = null;
try {
// Create a get object
m_httpGet = new HttpGet(apkurl);
// Execute the html request
m_httpResponse = m_httpClient.execute(m_httpGet);
HttpEntity entity = m_httpResponse.getEntity();
// See if we get a response
if (entity != null) {
InputStream instream = entity.getContent();
byte[] buffer = new byte[1024];
// Write out the file
int len1 = 0;
while ((len1 = instream.read(buffer)) != -1) {
fos.write(buffer, 0, len1);
}
fos.close();
instream.close();// till here, it works fine - .apk is download to my sdcard in download file
}
} catch (ConnectTimeoutException cte) {
// Toast.makeText(MainApplication.m_context, "Connection Timeout", Toast.LENGTH_SHORT).show();
return false;
} catch (Exception e) {
return false;
} finally {
m_httpClient.getConnectionManager().closeExpiredConnections();
}
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(
Uri.fromFile(new File(Environment.getExternalStorageDirectory() + "/download/" + "app.apk")),
"application/vnd.android.package-archive");
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
MainApplication.getApp().getApplicationContext().startActivity(intent);
// System.exit(0);
} catch (IOException e) {
Debug.ERROR(CLASSNAME, METHODNAME, "Failed to update new apk");
return false;
} catch (Exception e1) {
Debug.ERROR(CLASSNAME, METHODNAME, "Failed to update new apk");
return false;
}
return true;

Make sure you have the android.permission.INSTALL_PACKAGES permission declared in your AndroidManifest.xml.
Then get your APK path:
File apkFile = new File(Environment.getExternalStorageDirectory() + "/download/" + "app.apk");
Now run the Intent:
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setDataAndType(Uri.fromFile(apkFile), "application/vnd.android.package-archive");
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
startActivity(intent);

All downloads you do with the device...
To clarify what I mean with "Downloads" here is a screenshot. This is the standart download folder for Android 5 on Nexus 4. When I click on the apk inside this, I dont get the prompt to install a .apk. Instead the HTML-Viewer or other useless stuff shows up to choose...
One possible mistake could be the DownloadManager.. maybe he "tags" the downloaded file wrong so its not interpreted as an apk file, I don't know... but I call
promptInstall.setDataAndType(Uri.fromFile(new File(Environment.getExternalStorageDirectory() + "/download/myapp.apk")), "application/vnd.android.package-archive");

Android: How do I download a file from a dynamic url webview

In my app I am using a webview to navigate through to a site, automatically fill in a web form using javascript then submit to obtain a link to a CSV export file.
The link looks like this: XYZ.com/TEST/index/getexport?id=130.
I'd like to download the file this URL points to, then when complete read it into a local database but I'm having trouble downloading the linked file.
If I simply try to open the URL in webview I get an error from the webpage telling me no such file exists.
If I use the Download Manager to download it myself, the source code is downloaded as an html file, not the associated .csv file.
I can open the url with an ACTION_VIEW intent and a browser (chrome) downloads the correct file, but this way I have no notification of when the download completes.
Any ideas of how to download my .CSV file?

To download a file from webview use this :
mWebView.setDownloadListener(new DownloadListener(){
public void onDownloadStart(String url, String userAgent, String contentDisposition, String mimetype, long contentLength){
Intent i = new Intent(Intent.ACTION_VIEW);
i.setData(Uri.parse(url));
startActivity(i);
}
});
Hope this helps.

You could resort to manually downloading the file from the url using an AsyncTask.
Here id the background part:
#Override
protected String doInBackground(Void... params) {
String filename = "inputAFileName";
HttpURLConnection c;
try {
URL url = new URL("http://someurl/" + filename);
c = (HttpURLConnection) url.openConnection();
c.setRequestMethod("GET");
c.setDoOutput(true);
c.connect();
} catch (IOException e1) {
return e1.getMessage();
}
File myFilesDir = new File(Environment
.getExternalStorageDirectory().getAbsolutePath()
+ "/Download");
File file = new File(myFilesDir, filename);
if (file.exists()) {
file.delete();
}
if ((myFilesDir.mkdirs() || myFilesDir.isDirectory())) {
try {
InputStream is = c.getInputStream();
FileOutputStream fos = new FileOutputStream(myFilesDir
+ "/" + filename);
byte[] buffer = new byte[1024];
int len1 = 0;
while ((len1 = is.read(buffer)) != -1) {
fos.write(buffer, 0, len1);
}
fos.close();
is.close();
} catch (Exception e) {
return e.getMessage();
}
if (file.exists()) {
return "File downloaded!";
} else {
Log.e(TAG, "file not found");
}
} else {
Log.e(TAG, "unable to create folder");
}
}
Perhaps it would make sense to refactor it so that the file is returned. Then you get the file as an argument in onPostExecute as soon as the download is complete.

How to download a file from a server and save it in specific folder in SD card in Android?

I have one requirement in my Android application. I need to download and save file in specific folder of SD card programmatically. I have developed source code, which is
String DownloadUrl = "http://myexample.com/android/";
String fileName = "myclock_db.db";
DownloadDatabase(DownloadUrl,fileName);
// and the method is
public void DownloadDatabase(String DownloadUrl, String fileName) {
try {
File root = android.os.Environment.getExternalStorageDirectory();
File dir = new File(root.getAbsolutePath() + "/myclock/databases");
if(dir.exists() == false){
dir.mkdirs();
}
URL url = new URL("http://myexample.com/android/");
File file = new File(dir,fileName);
long startTime = System.currentTimeMillis();
Log.d("DownloadManager" , "download url:" +url);
Log.d("DownloadManager" , "download file name:" + fileName);
URLConnection uconn = url.openConnection();
uconn.setReadTimeout(TIMEOUT_CONNECTION);
uconn.setConnectTimeout(TIMEOUT_SOCKET);
InputStream is = uconn.getInputStream();
BufferedInputStream bufferinstream = new BufferedInputStream(is);
ByteArrayBuffer baf = new ByteArrayBuffer(5000);
int current = 0;
while((current = bufferinstream.read()) != -1){
baf.append((byte) current);
}
FileOutputStream fos = new FileOutputStream( file);
fos.write(baf.toByteArray());
fos.flush();
fos.close();
Log.d("DownloadManager" , "download ready in" + ((System.currentTimeMillis() - startTime)/1000) + "sec");
int dotindex = fileName.lastIndexOf('.');
if(dotindex>=0){
fileName = fileName.substring(0,dotindex);
}
catch(IOException e) {
Log.d("DownloadManager" , "Error:" + e);
}
}
Now the issue is only empty file with filename myclock_db.db is saving in the path. but I need to download and save content of file in the specific folder. Tried several ways to get the file download, but I can't.

Your download URL is not a link to any file. It's a directory. Make sure its a file and exists. Also check your logcat window for error logs. One more suggestion, its always better to do a printStackTrace() in catch blocks instead of Logs. Its gives a more detailed view of the error.
Change this line:
URL url = new URL("http://myexample.com/android/");
to:
URL url = new URL("http://myexample.com/android/yourfilename.txt"); //some file url
Next, in catch block, add this line:
e.printStackTrace();
Also in the directory path, it should be something like this:
File dir = new File(root.getAbsolutePath() + "/mnt/sdcard/myclock/databases");
instead of
File dir = new File(root.getAbsolutePath() + "/myclock/databases");
Next, make sure you have acquired permission for writing to external storage in Android manifest.

How to read PDF file saved to internal storage of device?

I am using following code to download and read a PDF file from internal storage on device.
I am able to download the files successfully to the directory:
data/data/packagename/app_books/file.pdf
But I am unable to read the file using a PDF reader application like Adobe Reader.
Code to download file
//Creating an internal dir;
File mydir = getApplicationContext().getDir("books", Context.MODE_WORLD_READABLE);
try {
File file = new File(mydir, outputFileName);
URL downloadUrl = new URL(url);
URLConnection ucon = downloadUrl.openConnection();
ucon.connect();
InputStream is = ucon.getInputStream();
FileOutputStream fos = new FileOutputStream(file);
byte data[] = new byte[1024];
int current = 0;
while ((current = is.read(data)) != -1) {
fos.write(data, 0, current);
}
is.close();
fos.flush();
fos.close();
isFileDownloaded=true;
} catch (IOException e) {
e.printStackTrace();
isFileDownloaded = false;
System.out.println(outputFileName + " not downloaded");
}
if (isFileDownloaded)
System.out.println(outputFileName + " downloaded");
return isFileDownloaded;
Code to read the file
PackageManager packageManager = getPackageManager();
Intent testIntent = new Intent(Intent.ACTION_VIEW);
testIntent.setType("application/pdf");
List list = packageManager.queryIntentActivities(testIntent,
PackageManager.MATCH_DEFAULT_ONLY);
try {
Intent intent = new Intent();
intent.setAction(Intent.ACTION_VIEW);
File fileToRead = new File(
"/data/data/com.example.filedownloader/app_books/Book.pdf");
Uri uri = Uri.fromFile(fileToRead.getAbsoluteFile());
intent.setDataAndType(uri, "application/pdf");
startActivity(intent);
} catch (Exception ex) {
Log.i(getClass().toString(), ex.toString());
Toast.makeText(MainActivity.this,
"Cannot open your selected file, try again later",
Toast.LENGTH_SHORT).show();
}
All works fine but the reader app says "File Path is not valid".

Your path is only valid for your app. Place the file in a place where other apps can 'see' it. Use GetExternalFilesDir() or getExternalStorageDirectory().

Note about files which are created inside the directory created by Context.getDir(String name, int mode) that they will only be accessible by your own application; you can only set the mode of the entire directory, not of individual files.
So you can use Context.openFileOutput(String name, int mode). I'm re-using your code for an example:
try {
// Now we use Context.MODE_WORLD_READABLE for this file
FileOutputStream fos = openFileOutput(outputFileName,
Context.MODE_WORLD_READABLE);
// Download data and store it to `fos`
// ...
You might want to take a look at this guide: Using the Internal Storage.

If you would like to keep the file app specific, you can use PdfRenderer available for Lollipop and above builds. There are great tutorials on google and youtube that work well. The method you are using is a secure way to store a PDF file that is only readable from inside the app ONLY. No outside application like Adobe PDF Reader will be able to even see the file.It took me a lot of seaching but I found a solution to my specific usage by using this site and especially youtube.

How to download PDF file from asset folder to storage by making folder
make sure you have storage permission are given like marshmallow device support etc then follow these steps
private void CopyReadAssets()
{
AssetManager assetManager = getContext().getAssets();
FileInputStream in = null;
FileOutputStream out = null;
File sdcard = Environment.getExternalStorageDirectory();
File dir = new File(Environment.getExternalStorageDirectory()+File.separator+ "A_level");
File dir2;
if (dir.exists() && dir.isDirectory()){
Log.e("tag out", ""+ dir);
}else {
dir.mkdir();
Log.e("tag out", "not exist");
}
File file = new File(dir, mTitle+".pdf");
try
{
Log.e("tag out", ""+ file);
out = new FileOutputStream(file);
in = new FileInputStream (new File(mPath));
Log.e("tag In", ""+ in);
copyFile(in, out);
in.close();
in = null;
out.flush();
out.close();
out = null;
} catch (Exception e)
{
Log.e("tag out", ""+ out);
Log.e("tag In", ""+ in);
Log.e("tag", e.getMessage());
Log.e("tag", ""+file);
Log.i("tag",""+sdcard.getAbsolutePath() + "A_level");
}
}
private void copyFile(InputStream in, OutputStream out) throws IOException
{
byte[] buffer = new byte[1024];
int read;
while ((read = in.read(buffer)) != -1)
{
out.write(buffer, 0, read);
}
}