Dead simple async downloader of URLs to file or string, with support for shortened links, a progressdialog and a completion handler.

DownloadURL.java

    public static class DownloadResult {
        public void onFile(String path) {};
        public void onString(String string){};

        public void onFail() {};
    }

    /**
     * This class handles the download of stuff from the tubes.
     * It's an extension of AsyncTask, so it will download asynchronously.
     * You can download to a file, which will be downloaded to the {@link android.os.Environment#getExternalStorageDirectory()} folder,
     * or to a string.
     * The path to the file or the string will be returned to your handler.
     * You can pass in a ProgressDialog to be updated during the download.
     * You can pass in a shortened URL, it will expand it. Only tested with http://tiny.cc URLs.
     */
    public static class DownloadURL extends AsyncTask<String, Integer, String> {
        ProgressDialog progressDialog = null;
        boolean isFile = false;
        private final DownloadResult handler;


        public DownloadURL(ProgressDialog pd, boolean isFile, DownloadResult handler) {
            progressDialog = pd;
            this.isFile = isFile;
            this.handler = handler;
        }

        @Override
        protected String doInBackground(String... sUrl) {
            try {
                URL possibilyShortenedURL = new URL(sUrl[0]);
                URL url;
                URLConnection connection;

                HttpURLConnection ucon = (HttpURLConnection) possibilyShortenedURL.openConnection();
                if (ucon.getResponseCode() != 200) {
                    // yep, shortened
                    ucon.setInstanceFollowRedirects(false);
                    url = new URL(ucon.getHeaderField("Location"));
                    connection = url.openConnection();
                } else {
                    // real url
                    connection = ucon;
                    url = possibilyShortenedURL;
                }
                connection.connect();

                // this will be useful so that you can show a typical 0-100% progress bar
                int fileLength = connection.getContentLength();

                Log.v(TAG, "File length: " + fileLength);

                if (fileLength == -1) {
                    return null;
                }

                if (progressDialog != null)
                    progressDialog.setMax(fileLength / 1024);


                if (isFile) {
                    // download the file
                    InputStream input = new BufferedInputStream(url.openStream());

                    long total = 0;
                    int count;
                    byte data[] = new byte[1024];
                    File file = new File(Environment.getExternalStorageDirectory().getPath(), new File(url.getPath()).getName());
                    OutputStream output = new FileOutputStream(file);

                    while ((count = input.read(data)) != -1) {
                        if (isCancelled()) break;
                        total += count;
                        // publishing the progress....
                        publishProgress((int) total / 1024);// (int) (total * 100 / fileLength));
                        output.write(data, 0, count);
                    }

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

                    return file.getAbsolutePath();
                } else {

                    BufferedReader in = new BufferedReader(new InputStreamReader(url.openStream()));

                    String fullText = "";
                    String inputLine;

                    while ((inputLine = in.readLine()) != null)
                        fullText += inputLine;

                    in.close();
                    return fullText;
                }


            } catch (Exception e) {
                Log.e(TAG, "Download of " + sUrl[0] + " failed", e);
            }
            return null;
        }

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            if (progressDialog != null)
                progressDialog.show();
        }

        @Override
        protected void onProgressUpdate(Integer... progress) {
            super.onProgressUpdate(progress);
            if (progressDialog != null)
                progressDialog.setProgress(progress[0]);
        }

        @Override
        protected void onPostExecute(String s) {
            if (s == null)
                handler.onFail();
            if (isFile)
                handler.onFile(s);
            else
                handler.onString(s);
        }
    }