Android: How to refer to the file downloaded by DownloadManager

Question

I have used the Download Manager Class to download a text file, the code that I download the file is:

private long enqueue
private DownloadManager dm;
String server_ip = "http://192.168.0.1/";

Request request = new Request(Uri.parse(server_ip + "test.txt"));
// Store to common external storage:
request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "test.txt");
enqueue = dm.enqueue(request);

And I have a boardcast receiver to check if the download is successful. If the download is successful, I will try to display the txt file in a textView:

BroadcastReceiver receiver = new BroadcastReceiver() {

    @Override
    public void onReceive(Context context, Intent intent) {

        String action = intent.getAction();
        if (DownloadManager.ACTION_DOWNLOAD_COMPLETE.equals(action)) {

            Query query = new Query();
            query.setFilterById(enqueue);
            Cursor c = dm.query(query);

            for (c.moveToFirst(); !c.isAfterLast(); c.moveToNext()) {
                int columnIndex = c.getColumnIndex(DownloadManager.COLUMN_STATUS);

                // Check if the download is successful
                if (DownloadManager.STATUS_SUCCESSFUL == c.getInt(columnIndex)) {

                    // Get the downloaded file and display the test.txt in a textView
                    File file = new File(storage_directory,"test.txt");
                    StringBuilder text = new StringBuilder();
                    try {
                        BufferedReader br = new BufferedReader(new FileReader(file));
                        String line;

                        while ((line = br.readLine()) != null) {
                            text.append(line);
                            text.append('\n');
                        }
                        br.close();

                        TextView tv = (TextView)findViewById(R.id.textView);
                        tv.setText(text);
                    }
                    catch (Exception e) {
                        //You'll need to add proper error handling here
                    }
                }
            }
        }
    }
}

One problem I found is if there is already a file with the same file name, "text.txt", the device will rename the newly download file to "text-1.txt". As a result when I try to display the newly downloaded file, it will display the old "test.txt" file instead. I would like to ask how can I refer to the new file when the download is successful, instead of specify a file name like what I did:

File file = new File(storage_directory,"test.txt");

Also, I have downloadeded the file to the external storage. I know if I did not add this line:

request.setDestinationInExternalPublicDir(Environment.DIRECTORY_DOWNLOADS, "test.txt");

when I send the request to the download manager, the file will be donwloaded to an internal storage. How can I refer to the file in this case?

Thank you very much.

Update: If I add this line after received the file successfully in the broadcast receiver:

String uriString = c.getString(c.getColumnIndex(DownloadManager.COLUMN_LOCAL_URI));

The uriString give me

file:///storage/emulated/0/Download/test.txt

score 3 · Accepted Answer · answered May 29 '16 at 15:10

3

Having many attempts, I found a way to solve my problem. I do not know if this is a good solution, but it seems work. I added the following code after it received the file successfully in the broadcast receiver, that is I added:

int filenameIndex = c.getColumnIndex(DownloadManager.COLUMN_LOCAL_FILENAME);
String filename = c.getString(filenameIndex);
File file = new File(filename);

and removed this code:

File file = new File(storage_directory,"test.txt");

after:

if (DownloadManager.STATUS_SUCCESSFUL == c.getInt(columnIndex)) {

By doing so, it will refer to the new downloaded file even the system renamed the file.

answered May 29 '16 at 15:10

eepty

716
3
10
28

Querying the download manager is indeed the way to get the local file. If you don't need the local file name until the download has completed, then this is the way to go. – user149408 Jun 04 '16 at 16:39
Using COLUMN_LOCAL_FILENAME is deprecated in API 24 and throws a SecurityException in Nougat – roplacebo Feb 13 '17 at 14:17

Android: How to refer to the file downloaded by DownloadManager

1 Answers1