download files in a single progress bar

问题

I have a progress bar managed by a AsyncTask which downloads some files from the internet.

private class DownloadImgs extends AsyncTask<Void, String, Void> {

            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                showDialog(progress_bar_type);
            }


            @Override
            protected Void doInBackground(Void ...params) {
               for(GetCountry gc : listCountry){
           getdownloadedFiles(gc.getUrl());}

           return null;

            }


            protected void onProgressUpdate(String... progress) {

                pDialog.setProgress(Integer.parseInt(progress[0]));
           }

            @Override
            protected void onPostExecute(Void result) {

                dismissDialog(progress_bar_type);


            }

The method which allows me to download the files:

public void getdownloadedFiles(String url)

            {

                int count;
                 try {

                  URL urlImg = new URL(url);
                  URLConnection connection = urlImg.openConnection();
                  connection.connect();

                  int lenghtOfFile = connection.getContentLength();
                  InputStream input = new BufferedInputStream(urlImg.openStream(), 8192);


                  OutputStream output = new FileOutputStream(folder+"/"+name);

                  byte data[] = new byte[1024];

                  long total = 0;

                  while ((count = input.read(data)) != -1) {
                      total += count;

                     publishProgress(""+(int)((total*100)/lenghtOfFile));

                      output.write(data, 0, count);

                  }


                  output.flush();           
                  output.close();
                  input.close();

                 } catch (Exception e) {
                     e.getMessage();
                 }


            }

This code works well, but the problem is that each file downloaded has it's own progress bar I want only one progress bar for all the downloaded files.

How can I achieve this? Thank you very much

回答1:

In your doInBackground() method, simply loop over the list of files you need to download inside of the single execution of your AsyncTask. You should probably also leverage the varargs nature of execute() to pass the list of URLs you need to download. In other words, something close to this:

DownloadImgs task = new DownloadImgs();
task.execute(url1, url2, url3, url4, url5);

The modify the task as such:

private class DownloadImgs extends AsyncTask<String, String, Void> {

    @Override
    protected Void doInBackground(String ...params) {

        for (String url : params) {
            getdownloadedFiles(url);
        }

        return null;
    }

    public void getdownloadedFiles(String url) {
        /* Existing code */
    }

    /* Other methods unchanged */
}

EDIT:

One method you could use to display all the file downloads as a single contiguous progress indicator is simply to update the progress by file count alone rather than file content. In other words, if you have 5 files just publishProgress() with values of 20 (1 * 100 / 5), 40 (2 * 100 / 5), 60 (3 * 100 / 5), 80 (4 * 100 / 5), and 100 (5 * 100 / 5) at the end of each file download.

If you need something more granular without pre-fetching the content length of every file, make each chunk increment with percentage. Note that you can also set the maximum level of the progress bar with setMax() to something other than 100 to make the math easier to work with. In the same 5 files example, you can set the progress bar maximum to 500, and for each download you would still add 100 to the total in the same fashion as you are now, but the total does not reset at the beginning of each download.

回答2:

Pass multiple URLs to your async task.

new DownloadImgs().execute(URL1,URL2,URL3);

it will show whole progress as a single progress bar.

来源：https://stackoverflow.com/questions/14107183/download-files-in-a-single-progress-bar

标签

java

android

android-asynctask

progress-bar