background upload with progress

BackgroundUploader.java

package com.grasys.shortupload.helper;

import android.app.ProgressDialog;
import android.content.Context;
import android.content.DialogInterface;
import android.os.AsyncTask;

import java.io.BufferedInputStream;
import java.io.BufferedReader;
import java.io.DataOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.InputStreamReader;
import java.net.HttpURLConnection;
import java.net.URL;

/**
 * Created by VuHung on 1/16/2015.
 */
public class BackgroundUploader extends AsyncTask<Void, Integer, Void> implements DialogInterface.OnCancelListener {

    private final Context context;
    private ProgressDialog progressDialog;
    private String url;
    private File file;

    public BackgroundUploader(Context context,String url, File file) {
        this.url = url;
        this.file = file;
        this.context = context;
    }

    @Override
    protected void onPreExecute() {
        progressDialog = new ProgressDialog(context);
        progressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
        progressDialog.setMessage("Uploading...");
        progressDialog.setCancelable(false);
        progressDialog.setMax((int) file.length());
        progressDialog.show();
    }

    @Override
    protected Void doInBackground(Void... v) {
        HttpURLConnection.setFollowRedirects(false);
        HttpURLConnection connection = null;
        String fileName = file.getName();
        try {
            connection = (HttpURLConnection) new URL(url).openConnection();
            connection.setRequestMethod("PUT");
            String boundary = "---------------------------boundary";
            String tail = "\r\n--" + boundary + "--\r\n";
            connection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + boundary);
            connection.setDoOutput(true);

            String metadataPart = "--" + boundary + "\r\n"
                    + "Content-Disposition: form-data; name=\"metadata\"\r\n\r\n"
                    + "" + "\r\n";

            String fileHeader1 = "--" + boundary + "\r\n"
                    + "Content-Disposition: form-data; name=\"uploadfile\"; filename=\""
                    + fileName + "\"\r\n"
                    + "Content-Type: application/octet-stream\r\n"
                    + "Content-Transfer-Encoding: binary\r\n";

            long fileLength = file.length() + tail.length();
            String fileHeader2 = "Content-length: " + fileLength + "\r\n";
            String fileHeader = fileHeader1 + fileHeader2 + "\r\n";
            String stringData = metadataPart + fileHeader;

            long requestLength = stringData.length() + fileLength;
            connection.setRequestProperty("Content-length", "" + requestLength);
            connection.setFixedLengthStreamingMode((int) requestLength);
            connection.connect();

            DataOutputStream out = new DataOutputStream(connection.getOutputStream());
            out.writeBytes(stringData);
            out.flush();

            int progress = 0;
            int bytesRead = 0;
            byte buf[] = new byte[1024];
            BufferedInputStream bufInput = new BufferedInputStream(new FileInputStream(file));
            while ((bytesRead = bufInput.read(buf)) != -1) {
                // write output
                out.write(buf, 0, bytesRead);
                out.flush();
                progress += bytesRead;
                // update progress bar
                publishProgress(progress);
            }

            // Write closing boundary and close stream
            out.writeBytes(tail);
            out.flush();
            out.close();

            // Get server response
            BufferedReader reader = new BufferedReader(new InputStreamReader(connection.getInputStream()));
            String line = "";
            StringBuilder builder = new StringBuilder();
            while ((line = reader.readLine()) != null) {
                builder.append(line);
            }

        } catch (Exception e) {
            // Exception
            e.printStackTrace();
        } finally {
            if (connection != null) connection.disconnect();
        }

        return null;
    }

    @Override
    protected void onProgressUpdate(Integer... progress) {
        progressDialog.setProgress((int) (progress[0]));
    }

    @Override
    protected void onPostExecute(Void v) {
        System.out.println("SUCCESS");
        progressDialog.setMax(0);
        progressDialog.setProgress(0);
        progressDialog.dismiss();
    }

    @Override
    public void onCancel(DialogInterface dialog) {
        cancel(true);
        dialog.dismiss();
    }
}

Many thanks!

wow, this is amazing, thank you so much !