Creating Bitmaps from the internet via Apache HttpClient

Last week I blogged about the Android DownloadManager. As a result I received the question how to create a bitmap from internet ressources the “normal” way.

Here is a small example which uses the Apache HttpClient in Android to download a png file and create a bitmap from it. This bitmap will then be assigned to a ImageView.

Here 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">
	<Button android:text="Click to start download" android:onClick="downloadPicture"
		android:layout_height="wrap_content" android:layout_width="wrap_content" />
	<ImageView android:src="@drawable/icon" android:id="@+id/imageView1"
		android:layout_height="match_parent" android:layout_width="match_parent"></ImageView>
</LinearLayout>

package de.vogella.android.bitmap.httpdownload.simple;

import java.io.IOException;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.StatusLine;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.client.methods.HttpUriRequest;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.util.EntityUtils;

import android.app.Activity;
import android.app.ProgressDialog;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.View;
import android.widget.ImageView;

public class DownloadExampleActivity extends Activity {
	/** Called when the activity is first created. */
	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		setContentView(R.layout.main);

	}

	public void downloadPicture(View view) {
		final ProgressDialog dialog = ProgressDialog.show(this, "Download",
				"downloading");
		dialog.show();
		new Thread(new Runnable() {
			@Override
			public void run() {
				try {
					final Bitmap downloadBitmap = downloadBitmap("http://www.vogella.de/img/lars/LarsVogelArticle7.png");
					final ImageView imageView = (ImageView) findViewById(R.id.imageView1);
					runOnUiThread(new Runnable() {
						@Override
						public void run() {
							imageView.setImageBitmap(downloadBitmap);
						}
					});

				} catch (IOException e) {
					e.printStackTrace();
				} finally {
					dialog.dismiss();
				}
			}
		}).start();

	}

	private Bitmap downloadBitmap(String url) throws IOException {
		HttpUriRequest request = new HttpGet(url.toString());
		HttpClient httpClient = new DefaultHttpClient();
		HttpResponse response = httpClient.execute(request);

		StatusLine statusLine = response.getStatusLine();
		int statusCode = statusLine.getStatusCode();
		if (statusCode == 200) {
			HttpEntity entity = response.getEntity();
			byte[] bytes = EntityUtils.toByteArray(entity);

			Bitmap bitmap = BitmapFactory.decodeByteArray(bytes, 0,
					bytes.length);
			return bitmap;
		} else {
			throw new IOException("Download failed, HTTP response code "
					+ statusCode + " - " + statusLine.getReasonPhrase());
		}
	}
}

Also add the permission to use the internet to your app.

Hope this helps. A introduction to Networking with Android can be found here.

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