image downloading from internet

//MainActivity.java
package com.v3;
 
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.Random;
 
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Message;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
 
public class MainActivity extends Activity {
 
 
    ImageView imView;
    String imageUrl="http://variable3.com/files/images/email-sig.jpg";
    Random r= new Random();
   /** Called when the activity is first created. */ 
   @Override
   public void onCreate(Bundle icicle) {
       super.onCreate(icicle);
       setContentView(R.layout.main);
 
       Button bt3= (Button)findViewById(R.id.get_imagebt);
       bt3.setOnClickListener(getImgListener);
 
       imView = (ImageView)findViewById(R.id.imview);
       Log.i("img already downloaded","img");
   }    
 
   View.OnClickListener getImgListener = new View.OnClickListener()
   {
 
         public void onClick(View view) {
              // TODO Auto-generated method stub
 
              //i tried to randomize the file download, in my server i put 4 files with name like
                       //png0.png, png1.png, png2.png so different file is downloaded in button press
             int i =r.nextInt(4);
              downloadFile(imageUrl);
              Log.i("im url",imageUrl);
         }
 
   };
 
 
   Bitmap bmImg;
   void downloadFile(String fileUrl){
         URL myFileUrl =null;  
 
         //Message msg = Message.obtain();//n
         try {
              myFileUrl= new URL(fileUrl);
         } catch (MalformedURLException e) {
              // TODO Auto-generated catch block
              e.printStackTrace();
         }
         try {
              HttpURLConnection conn= (HttpURLConnection)myFileUrl.openConnection();
              conn.setDoInput(true);
              conn.connect();
              int length = conn.getContentLength();
              InputStream is = conn.getInputStream();
              Log.i("im connected","Download");
              bmImg = BitmapFactory.decodeStream(is);
 
 
 
              imView.setImageBitmap(bmImg);
         } catch (IOException 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"
    >
 
    <Button 
    android:id="@+id/get_imagebt"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:text="Get an image"
    android:layout_gravity="center"
    />
    <ImageView 
      android:layout_width="wrap_content" 
      android:id="@+id/imview"
       android:layout_height="wrap_content" 
       android:src="@drawable/icon"
       android:layout_gravity="center"/>  
 
 
</LinearLayout>
//menifest.xml
<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
      package="com.v3"
      android:versionCode="1"
      android:versionName="1.0">
    <uses-sdk android:minSdkVersion="8" />
 
    <application android:icon="@drawable/icon" android:label="@string/app_name">
        <activity android:name=".MainActivity"
                  android:label="@string/app_name">
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
 
    </application>
 
<uses-permission android:name="android.permission.INTERNET"></uses-permission>
 
        <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE"></uses-permission>
 
        <uses-permission android:name="android.permission.READ_PHONE_STATE"></uses-permission>
</manifest>