Android ProgressBar in ListView while using DownloadManager

Question

I have a ListView in which each item represents a PDF file. When the user clicks on an item, the application must download the file on external storage. Now the download doe

Answer 1

I'd use an AsyncTask for that, and make the wheel appear / disappear in onPreCreate & onPostCreate

private class MyDownloader extends AsyncTask<String, Void, File>{

    @Override
    protected void onPreExecute() {
        loader.setVisibility(View.VISIBLE);
    }

    @Override
    protected File doInBackground(String... params) {
        //Download and save file here, and return the result, which will be fed into the onPostExecute method
        return file;
    }

    @Override
    protected void onPostExecute(File file) {
        super.onPostExecute(file);
        loader.setVisibility(View.GONE);
    }
}

Then start the task with new MyDownloader().execute("linktopdf"); or something like that (what you put in .execute will be fed into the doInBackground method)

Answer 2

Ok so I managed to do what I wanted to do with a HashTable :

// HashTable to store download id's and loaders
Hashtable<Long, SyncedProgressBar> storeTable = new Hashtable<Long, SyncedProgressBar>();

In my onClickListener method, after loader[z] and lastDownload[ld] take their value, I put them in the HashTable : ( the downloa id will be the key, the loader will be the value )

// Storing download id and loader in HashTable
storeTable.put(lastDownload[ld], loader[z]);

In my Broadcast Receiver's onReceive method, instead of doing this :

if(lastDownload[y] == referenceId)

I look if the HashTable contains the download id of the intent :

if(storeTable.containsKey(referenceId))

And I put the correct value in the loader :

loader[y] = storeTable.get(referenceId);

Then I just have to put the loader's visibility to GONE where I want. This solution works for me, but I will update it if I find something new.

Here is my new code :

In the onClickListener method : ( not complete here )

// Loader of the clicked item is made visible
loader[z].setVisibility(View.VISIBLE);

// Construction of the URL
SharedPreferences codeSaveUrl = getSharedPreferences(PREFS_TEXT,Context.MODE_PRIVATE);
url2 = codeSaveUrl.getString("defaut", ""); // Organization code
uri = url10 + url2 + "&file=" + udl ;

// URL parse to URI
Uri myuri = Uri.parse(uri);

// Enqueue file to downloads, with notification. Storage of download id in a table
lastDownload[ld] = mgr.enqueue(new DownloadManager.Request(myuri)
.setAllowedNetworkTypes(DownloadManager.Request.NETWORK_WIFI |DownloadManager.Request.NETWORK_MOBILE)
.setAllowedOverRoaming(false)
.setTitle(udl + ".pdf")
.setDescription("Téléchargement en cours")
.setDestinationInExternalPublicDir("/Protocols/", (udl+".pdf"))
.setNotificationVisibility(DownloadManager.Request.VISIBILITY_VISIBLE));

// Storing download id and loader in HashTable
storeTable.put(lastDownload[ld], loader[z]);

// Increment variables for next downloads
ld=ld+1;
z=z+1;

Broadcast Receiver :

// Broadcast Receiver called when a download is finished
BroadcastReceiver onComplete = new BroadcastReceiver() {
    public void onReceive(Context context, Intent intent) {
        // referenceId is the download's id for which the method is called
        long referenceId = intent.getLongExtra(DownloadManager.EXTRA_DOWNLOAD_ID, -1);
        // If y (=0 at the beginning) is inferior to the number of downloads
        if(y <ld){
            // If the HashTable contains the Key-download-id for which the method is called
            if(storeTable.containsKey(referenceId)){
                // Loader takes the value for the key
                loader[y] = storeTable.get(referenceId);
                // We define a cursor depending on the id
                Cursor c = mgr.query(new DownloadManager.Query().setFilterById(referenceId));
                if(c.moveToFirst()){
                    // Download status recovery
                    int x = c.getInt(c.getColumnIndex(DownloadManager.COLUMN_STATUS));
                    switch(x){
                    // If download is paused, pending or running, we do nothing
                    case DownloadManager.STATUS_PAUSED:
                    case DownloadManager.STATUS_PENDING:
                    case DownloadManager.STATUS_RUNNING:
                        break;
                    // If file has successfully been downloaded, loader is hidden
                    case DownloadManager.STATUS_SUCCESSFUL:
                        loader[y].setVisibility(View.GONE); 
                        // Increment y to go to next download
                        y=y+1;
                        break;
                    // If download failed, it is retried
                    case DownloadManager.STATUS_FAILED:
                        //TODO: retry download
                        break;
                    }
                }
            }
        }
    }
};

Answer 3

Please note that DownloadManager.enqueue is asynchronous, it means mgr.enqeue returns almost immediately and after that your current code sets spinner back to invisible.

To hide spinner you have to register a broadcast receiver to receive notification when download completes. You then have to find corresponding spinner and hide it. Please note that download can fail (and notification is still sent in this case).

CommonsWare has posted an example showing how to work with DownloadManager.