Yet another blog

I needed to load remote images to my 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 resources.

Here is the layout file

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 id="@+id/get_imagebt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Get an image"
android:layout_gravity="center"
/>
< ImageView id="@+id/imview"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_gravity="center"
/>
< /LinearLayout>


The java code goes like it


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();
int[] bitmapData =new int[length];
byte[] bitmapData2 =new byte[length];
InputStream is = conn.getInputStream();

bmImg = BitmapFactory.decodeStream(is);
imView.setImageBitmap(bmImg);
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}


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, i tried to read the whole bytes of image data, do other trial and error method. I was confused about the Bitmap tranformation technology. Then i found that there is a built in class known as BitmapFactory, it can produce bitmap directly from stream. This saved a lot of my efforts. Hope it will come useful to you.

Happy andcoding :)