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Loading images from a remote server

This tutorial demonstrates how to load a remote image into your application and bind this image to an ImageView object. HttpURLConnection is used to download the image data and BitmapFactory is used to produce the bitmap which will be used as ImageView resource.

Here is the Java code:

import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.util.HashMap;
import java.util.Map;
import java.util.Random;

import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;
import android.widget.EditText;
import android.widget.ImageView;

public class HTTPTest extends Activity {
     

     ImageView imView;
     String imageUrl="http://11.0.6.23/";
     Random r;
    /** Called when the activity is first created. */ 
    @Override
    public void onCreate(Bundle icicle) {
        super.onCreate(icicle);
        setContentView(R.layout.main);
        r= new Random();
       
        Button bt3= (Button)findViewById(R.id.get_imagebt);
        bt3.setOnClickListener(getImgListener);
        imView = (ImageView)findViewById(R.id.imview);
    }    

    View.OnClickListener getImgListener = new View.OnClickListener()
    {

          @Override
          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+"png"+i+".png");
               Log.i("im url",imageUrl+"png"+i+".png");
          }
     
    };

   
    Bitmap bmImg;
    void downloadFile(String fileUrl){
          URL myFileUrl =null;          
          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();
               
               bmImg = BitmapFactory.decodeStream(is);
               imView.setImageBitmap(bmImg);
          } catch (IOException e) {
               // TODO Auto-generated catch block
               e.printStackTrace();
          }
     }
}

This is the layout file (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="Hello World, HTTPImage load test"
    />
    <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:id="@+id/imview"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_gravity="center"
    />
</LinearLayout>

The code is pretty simple and easy, most of you might already have done this, I am a slow learner, I tried different ways first, U tried to read the whole bytes of the image data, do another trial and error method. I was confused about the Bitmap transformation technology. Then I found that there is a built in class known as BitmapFactory, it can produce bitmaps directly from streams. This saved a lot of my efforts. Hope it will be useful for you. Shimugool

NB: you'll need to grant android.permission.INTERNET permission.