Android DownloadManager API - opening file after download?

Question

I am facing problem of opening downloaded file after successfull download via DownloadManager API. In my code:

Uri uri=Uri.parse(\"http://www.nasa.gov/images/con         


        

Answer 1

Problem

Android DownloadManager API - opening file after download?

Solution

/**
 * Used to download the file from url.
 * 

 * 1. Download the file using Download Manager.
 *
 * @param url      Url.
 * @param fileName File Name.
 */
public void downloadFile(final Activity activity, final String url, final String fileName) {
    try {
        if (url != null && !url.isEmpty()) {
            Uri uri = Uri.parse(url);
            activity.registerReceiver(attachmentDownloadCompleteReceive, new IntentFilter(
                    DownloadManager.ACTION_DOWNLOAD_COMPLETE));

            DownloadManager.Request request = new DownloadManager.Request(uri);
            request.setMimeType(getMimeType(uri.toString()));
            request.setTitle(fileName);
            request.setDescription("Downloading attachment..");
            request.allowScanningByMediaScanner();
            request.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE_NOTIFY_COMPLETED);
            request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, fileName);
            DownloadManager dm = (DownloadManager) activity.getSystemService(Context.DOWNLOAD_SERVICE);
            dm.enqueue(request);
        }
    } catch (IllegalStateException e) {
        Toast.makeText(activity, "Please insert an SD card to download file", Toast.LENGTH_SHORT).show();
    }
}

/**
 * Used to get MimeType from url.
 *
 * @param url Url.
 * @return Mime Type for the given url.
 */
private String getMimeType(String url) {
    String type = null;
    String extension = MimeTypeMap.getFileExtensionFromUrl(url);
    if (extension != null) {
        MimeTypeMap mime = MimeTypeMap.getSingleton();
        type = mime.getMimeTypeFromExtension(extension);
    }
    return type;
}

/**
 * Attachment download complete receiver.
 * 

 * 1. Receiver gets called once attachment download completed.
 * 2. Open the downloaded file.
 */
BroadcastReceiver attachmentDownloadCompleteReceive = new BroadcastReceiver() {
    @Override
    public void onReceive(Context context, Intent intent) {
        String action = intent.getAction();
        if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(action)) {
            long downloadId = intent.getLongExtra(
                    DownloadManager.EXTRA_DOWNLOAD_ID, 0);
            openDownloadedAttachment(context, downloadId);
        }
    }
};

/**
 * Used to open the downloaded attachment.
 *
 * @param context    Content.
 * @param downloadId Id of the downloaded file to open.
 */
private void openDownloadedAttachment(final Context context, final long downloadId) {
    DownloadManager downloadManager = (DownloadManager) context.getSystemService(Context.DOWNLOAD_SERVICE);
    DownloadManager.Query query = new DownloadManager.Query();
    query.setFilterById(downloadId);
    Cursor cursor = downloadManager.query(query);
    if (cursor.moveToFirst()) {
        int downloadStatus = cursor.getInt(cursor.getColumnIndex(DownloadManager.COLUMN_STATUS));
        String downloadLocalUri = cursor.getString(cursor.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI));
        String downloadMimeType = cursor.getString(cursor.getColumnIndex(DownloadManager.COLUMN_MEDIA_TYPE));
        if ((downloadStatus == DownloadManager.STATUS_SUCCESSFUL) && downloadLocalUri != null) {
            openDownloadedAttachment(context, Uri.parse(downloadLocalUri), downloadMimeType);
        }
    }
    cursor.close();
}

/**
 * Used to open the downloaded attachment.
 * 

 * 1. Fire intent to open download file using external application.
 *
 * 2. Note:
 * 2.a. We can't share fileUri directly to other application (because we will get FileUriExposedException from Android7.0).
 * 2.b. Hence we can only share content uri with other application.
 * 2.c. We must have declared FileProvider in manifest.
 * 2.c. Refer - https://developer.android.com/reference/android/support/v4/content/FileProvider.html
 *
 * @param context            Context.
 * @param attachmentUri      Uri of the downloaded attachment to be opened.
 * @param attachmentMimeType MimeType of the downloaded attachment.
 */
private void openDownloadedAttachment(final Context context, Uri attachmentUri, final String attachmentMimeType) {
    if(attachmentUri!=null) {
        // Get Content Uri.
        if (ContentResolver.SCHEME_FILE.equals(attachmentUri.getScheme())) {
            // FileUri - Convert it to contentUri.
            File file = new File(attachmentUri.getPath());
            attachmentUri = FileProvider.getUriForFile(activity, "com.freshdesk.helpdesk.provider", file);;
        }

        Intent openAttachmentIntent = new Intent(Intent.ACTION_VIEW);
        openAttachmentIntent.setDataAndType(attachmentUri, attachmentMimeType);
        openAttachmentIntent.setFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
        try {
            context.startActivity(openAttachmentIntent);
        } catch (ActivityNotFoundException e) {
            Toast.makeText(context, context.getString(R.string.unable_to_open_file), Toast.LENGTH_LONG).show();
        }
    }
}

Initialize FileProvider Details

Decleare FileProvider in AndroidManifest

Add the following file "res -> xml -> file_path.xml"

Note

Why Use FileProvider

1. From Android 7.0 we can't share FileUri with other appliction.
2. Using "DownloadManager.COLUMN_LOCAL_URI" we will get only FileUri hence we need to convert it into ContentUri & share with other application.

Provblem with using "DownloadManager.getUriForDownloadedFile(long id)"

1. Don't use "DownloadManager.getUriForDownloadedFile(long id)" - To get Uri from downloadId to open the file using external application.
2. Because from Android 6.0 & 7.0 "getUriForDownloadedFile" method returns local uri (Which can be accessed only by our application), we can't share that Uri with other application because they can't access that uri (But it is fixed in Android 7.1 see Android Commit Here).
3. Refere Android source code DownloadManager.java & Downloads.java
4. Hence always use Column "DownloadManager.COLUMN_LOCAL_URI" to get Uri.

Reference

1. https://developer.android.com/reference/android/app/DownloadManager.html
2. https://developer.android.com/reference/android/support/v4/content/FileProvider.html