Sample code using android.app.DownloadManager

android.app.DownloadManager (introduced in API Level 9) is a system service that handles long-running HTTP downloads. Clients may request that a URI be downloaded to a particular destination file. The download manager will conduct the download in the background, taking care of HTTP interactions and retrying downloads after failures or across connectivity changes and system reboots.





In order to permit your app download from internet, AndroidManifest.xml have to be modified to grant permission of "android.permission.INTERNET".

Java code:

package com.exercise.AndroidDownloadManager;

import java.io.FileInputStream;
import java.io.FileNotFoundException;

import android.app.Activity;
import android.app.DownloadManager;
import android.content.BroadcastReceiver;
import android.content.Context;
import android.content.Intent;
import android.content.IntentFilter;
import android.content.SharedPreferences;
import android.content.SharedPreferences.Editor;
import android.database.Cursor;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.net.Uri;
import android.os.Bundle;
import android.os.ParcelFileDescriptor;
import android.preference.PreferenceManager;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class AndroidDownloadManagerActivity extends Activity {
 
 final String DOWNLOAD_FILE = "http://goo.gl/w3XV3";

 final String strPref_Download_ID = "PREF_DOWNLOAD_ID";
 
 SharedPreferences preferenceManager;
 DownloadManager downloadManager;
 
 ImageView image;
 
   /** Called when the activity is first created. */
   @Override
   public void onCreate(Bundle savedInstanceState) {
       super.onCreate(savedInstanceState);
       setContentView(R.layout.main);
      
       preferenceManager
        = PreferenceManager.getDefaultSharedPreferences(this);
       downloadManager
        = (DownloadManager)getSystemService(DOWNLOAD_SERVICE);
      
       Button btnStartDownload = (Button)findViewById(R.id.startdownload);
       btnStartDownload.setOnClickListener(btnStartDownloadOnClickListener);
      
       image = (ImageView)findViewById(R.id.image);
   }
  
   Button.OnClickListener btnStartDownloadOnClickListener
   = new Button.OnClickListener(){

  @Override
  public void onClick(View v) {
   // TODO Auto-generated method stub
   
   Uri downloadUri = Uri.parse(DOWNLOAD_FILE);
   DownloadManager.Request request = new DownloadManager.Request(downloadUri);
   long id = downloadManager.enqueue(request);
   
   //Save the request id
   Editor PrefEdit = preferenceManager.edit();
   PrefEdit.putLong(strPref_Download_ID, id);
   PrefEdit.commit();

  }};

 @Override
 protected void onResume() {
  // TODO Auto-generated method stub
  super.onResume();

  IntentFilter intentFilter
   = new IntentFilter(DownloadManager.ACTION_DOWNLOAD_COMPLETE);
  registerReceiver(downloadReceiver, intentFilter);
 }

 @Override
 protected void onPause() {
  // TODO Auto-generated method stub
  super.onPause();
  unregisterReceiver(downloadReceiver);
 }
  
 private BroadcastReceiver downloadReceiver = new BroadcastReceiver() {

  @Override
  public void onReceive(Context arg0, Intent arg1) {
   // TODO Auto-generated method stub
   DownloadManager.Query query = new DownloadManager.Query();
   query.setFilterById(preferenceManager.getLong(strPref_Download_ID, 0));
   Cursor cursor = downloadManager.query(query);
   if(cursor.moveToFirst()){
    int columnIndex = cursor.getColumnIndex(DownloadManager.COLUMN_STATUS);
    int status = cursor.getInt(columnIndex);
    if(status == DownloadManager.STATUS_SUCCESSFUL){
     
     //Retrieve the saved request id
     long downloadID = preferenceManager.getLong(strPref_Download_ID, 0);
     
     ParcelFileDescriptor file;
     try {
      file = downloadManager.openDownloadedFile(downloadID);
      FileInputStream fileInputStream
       = new ParcelFileDescriptor.AutoCloseInputStream(file);
      Bitmap bm = BitmapFactory.decodeStream(fileInputStream);
      image.setImageBitmap(bm);
     } catch (FileNotFoundException e) {
      // TODO Auto-generated catch block
      e.printStackTrace();
     }
     
    }
   }
  } 
 };
}

main.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:orientation="vertical"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   >
<TextView 
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="@string/hello"
   />
<Button 
   android:id="@+id/startdownload"
   android:layout_width="fill_parent"
   android:layout_height="wrap_content"
   android:text="Start Download"
   />
<ImageView
   android:id="@+id/image"
   android:layout_width="fill_parent"
   android:layout_height="fill_parent"
   />
</LinearLayout>

Download the files.