问显示以百分比表示的进度对话框
EN

Stack Overflow用户

提问于 2016-02-20 17:42:05

回答 2查看 2.3K关注 0票数 2

我正在使用异步任务从互联网下载一些文件。对于这个问题，我知道向用户展示到目前为止的进展是非常相关的。我下载文件的所有实现都非常成功，但唯一的问题是进度对话框，即使启动了下载命令，这也显示为0%。

我就是这样做的

 // Show Dialog Box with Progress bar
  @Override
  protected Dialog onCreateDialog(int id) {
    switch (id) {
        case progress_bar_type:
            prgDialog = new ProgressDialog(this);
            prgDialog.setMessage("Downloading Mp3 file. Please wait...");
            prgDialog.setIndeterminate(false);
            prgDialog.setMax(100);
            prgDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            prgDialog.setCancelable(false);
            prgDialog.show();
            return prgDialog;
        default:
            return null;
    }
}



// Async Task Class
class DownloadMusicfromInternet extends AsyncTask<String, String, String> {

    // Show Progress bar before downloading Music
    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        // Shows Progress Bar Dialog and then call doInBackground method
        showDialog(progress_bar_type);
    }

    // Download Music File from Internet
    @Override
    protected String doInBackground(String... f_url) {
        int count;
        try {
            URL url = new URL(f_url[0]);
            URLConnection conection = url.openConnection();
            conection.connect();
            // Get Music file length
            int lenghtOfFile = conection.getContentLength();
            // input stream to read file - with 8k buffer
            InputStream input = new BufferedInputStream(url.openStream(),10*1024);
            // Output stream to write file in SD card
            OutputStream output = new FileOutputStream(f_url[1]);
            byte data[] = new byte[1024];
            long total = 0;
            while ((count = input.read(data)) != -1) {
                total += count;
                // Publish the progress which triggers onProgressUpdate method
                publishProgress("" + (int) ((total * 100) / lenghtOfFile));

                // Write data to file
                output.write(data, 0, count);
            }
            // Flush output
            output.flush();
            // Close streams
            output.close();
            input.close();
        } catch (Exception e) {
            Log.e("Error: ", e.getMessage());
        }
        return null;
    }

    // While Downloading Music File
    protected void onProgressUpdate(String... progress) {
        // Set progress percentage
        prgDialog.setProgress(Integer.parseInt(progress[0]));
    }

    // Once Music File is downloaded
    @Override
    protected void onPostExecute(String file_url) {
        // Dismiss the dialog after the Music file was downloaded
        dismissDialog(progress_bar_type);
        Toast.makeText(getApplicationContext(), "Download complete, playing Music", Toast.LENGTH_LONG).show();
    }
}