Android showing progress-bar during the back-end downloading and internet interaction

In this Blog i wants to introduce a way to download an image file from a given link and showing image on the screen. during the download we can see a download progress bar /waiting bar as spinner. please make a new project with the AndroidDownloadFileByProgressBar, we need to copy given layout to main.xml

1)

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent"
    android:orientation="vertical" >

    <!-- Download Button -->
    <Button android:id="@+id/btnProgressBar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:text="Download"
        android:layout_marginTop="50dip"/>
   
    <!-- Image view to show image after downloading -->
    <ImageView android:id="@+id/my_image"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"/>

</LinearLayout>

2) now copy the following code to main activity class AndroidDownloadFileByProgressBarActivity.java



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.app.Activity;
import android.app.Dialog;
import android.app.ProgressDialog;
import android.graphics.drawable.Drawable;
import android.os.AsyncTask;
import android.os.Bundle;
import android.os.Environment;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class AndroidDownloadFileByProgressBarActivity extends Activity {


Button btnShowProgress;


private ProgressDialog pDialog;
ImageView my_image;
// Progress dialog type (0 - for Horizontal progress bar)
public static final int progress_bar_type = 0;


private static String file_url = "http://www.trisolutions.in/images/1_android3.jpg";

@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);


btnShowProgress = (Button) findViewById(R.id.btnProgressBar);

my_image = (ImageView) findViewById(R.id.my_image);
/**
* Show Progress bar click event
* */
btnShowProgress.setOnClickListener(new View.OnClickListener() {

public void onClick(View v) {
// starting new Async Task
new DownloadFileFromURL().execute(file_url);
}
});
}

/**
* Showing Dialog
* */
@Override
protected Dialog onCreateDialog(int id) {
switch (id) {
case progress_bar_type:
pDialog = new ProgressDialog(this);
pDialog.setMessage("Downloading Image file. Please wait for a while...");
pDialog.setIndeterminate(false);
pDialog.setMax(100);
pDialog.setProgressStyle(ProgressDialog.STYLE_SPINNER);
//pDialog.setCancelable(true);
pDialog.show();
return pDialog;
default:
return null;
}
}

/**
* Background Async Task to download file
* */
class DownloadFileFromURL extends AsyncTask<String, String, String> {

/**
* Before starting background thread
* Show Progress Bar Dialog
* */
@Override
protected void onPreExecute() {
super.onPreExecute();
showDialog(progress_bar_type);
}

/**
* Downloading file in background thread
* */
@Override
protected String doInBackground(String... f_url) {
int count;
       try {
           URL url = new URL(f_url[0]);
           URLConnection conection = url.openConnection();
           conection.connect();
           // getting file length
           int lenghtOfFile = conection.getContentLength();

           // input stream to read file - with 8k buffer
           InputStream input = new BufferedInputStream(url.openStream(), 8192);
         
           // Output stream to write file
           OutputStream output = new FileOutputStream("/sdcard/downloadedfile.jpg");

           byte data[] = new byte[1024];

           long total = 0;

           while ((count = input.read(data)) != -1) {
               total += count;
               // publishing the progress....
               // After this onProgressUpdate will be called
               publishProgress(""+(int)((total*100)/lenghtOfFile));
             
               // writing data to file
               output.write(data, 0, count);
           }

           // flushing output
           output.flush();
         
           // closing streams
           output.close();
           input.close();
         
       } catch (Exception e) {
        Log.e("Error: ", e.getMessage());
       }
     
       return null;
}

/**
* Updating progress bar
* */
protected void onProgressUpdate(String... progress) {

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

/**
* After completing background task
* Dismiss the progress dialog
* **/
@Override
protected void onPostExecute(String file_url) {

dismissDialog(progress_bar_type);


String imagePath = Environment.getExternalStorageDirectory().toString() + "/downloadedfile.jpg";

my_image.setImageDrawable(Drawable.createFromPath(imagePath));
}

}
}

3) run on emulator but do not forget the following lines as you need these lines inside yours manifest :)


 <!-- Permission: Allow Connect to Internet -->
    <uses-permission android:name="android.permission.INTERNET" />
   
    <!-- Permission: Writing to SDCard -->
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

4) check yours avd that there is an sd card mentioned or not? if not than give specifications to it.

have a great day with Android :)