android ในส่วนของ upload file to server และ download ช่วยแนะนำด้วยครับ

package com.example.download;
import java.io.BufferedInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URL;
import java.net.URLConnection;

import android.os.AsyncTask;
import android.os.Bundle;
import android.os.StrictMode;
import android.annotation.SuppressLint;
import android.app.Activity;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.util.Log;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.EditText;

public class MainActivity extends Activity {

    public static final int DIALOG_DOWNLOAD_PROGRESS = 0;
    private Button startBtn;
    private ProgressDialog mProgressDialog;
    private String URLDownload;
    private EditText txtURL;

    /** Called when the activity is first created. */
    @SuppressLint("NewApi")
	@Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        // Permission StrictMode
        if (android.os.Build.VERSION.SDK_INT > 9) {
            StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
            StrictMode.setThreadPolicy(policy);
        }
        
        // btnDownload
        startBtn = (Button)findViewById(R.id.btnDownload);
        startBtn.setOnClickListener(new OnClickListener(){
            public void onClick(View v) {
                startDownload();
            }
        });
    }

    private void startDownload() {
        // editText1
        txtURL = (EditText)findViewById(R.id.editText1);
        URLDownload = txtURL.getText().toString();
        new DownloadFileAsync().execute(URLDownload);
    }
    @Override
    protected Dialog onCreateDialog(int id) {
        switch (id) {
        case DIALOG_DOWNLOAD_PROGRESS:
            mProgressDialog = new ProgressDialog(this);
            mProgressDialog.setMessage("Downloading file..");
            mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
            mProgressDialog.setCancelable(false);
            mProgressDialog.show();
            return mProgressDialog;
        default:
            return null;
        }
    }

class DownloadFileAsync extends AsyncTask<String, String, String> {

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

    @Override
    protected String doInBackground(String... aurl) {
        int count;

	    try {
	
	    URL url = new URL(aurl[0]);
	    URLConnection conexion = url.openConnection();
	    conexion.connect();
	
	    int lenghtOfFile = conexion.getContentLength();
	    Log.d("ANDRO_ASYNC", "Lenght of file: " + lenghtOfFile);
	
	    InputStream input = new BufferedInputStream(url.openStream());
	    
	    // Get File Name from URL
	    String fileName = URLDownload.substring( URLDownload.lastIndexOf('/')+1, URLDownload.length() );
	
	    OutputStream output = new FileOutputStream("/sdcard/"+fileName);
	    
	    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) {}
		
	    return null;

    }
    protected void onProgressUpdate(String... progress) {
         Log.d("ANDRO_ASYNC",progress[0]);
         mProgressDialog.setProgress(Integer.parseInt(progress[0]));
    }

    @Override
    protected void onPostExecute(String unused) {
        dismissDialog(DIALOG_DOWNLOAD_PROGRESS);
    }
  }
}