<pre class="brush: java">
package info.kahimyang.storm;

import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import javax.imageio.ImageIO;
import javax.servlet.ServletException;
import javax.servlet.ServletOutputStream;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(name = "ImageDownloader", urlPatterns = {"/ImageDownloader"})
public class ImageDownloader extends HttpServlet {

 protected void processRequest(HttpServletRequest request, 
 HttpServletResponse response)
 throws ServletException, IOException {

 // Get values of parameters
 String imageType = request.getParameter("type");
 String media = request.getParameter("image_url");

 // Fetch the image
 URL url = new URL(media);
 HttpURLConnection connection = 
 (HttpURLConnection) url.openConnection();
 
 connection.addRequestProperty("User-Agent", "Mozilla");
 
 // Read the image into a BufferedImage object
 InputStream stream = connection.getInputStream();
 BufferedImage image = ImageIO.read(stream);

 // Get the dimension of the image
 int H = image.getHeight();
 int W = image.getWidth();

 // Crop the image from the top. This example crops our
 // image 70 pixels from the top
 BufferedImage cropped = image.getSubimage(0, 70, W, H - 70);
 
 // Write the image into ByteArrayOutputStream
 ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
 ImageIO.write(cropped, imageType, byteStream);

 // Update response
 ServletOutputStream out = response.getOutputStream();
 response.setContentType("image/" + imageType);
 response.setContentLength(byteStream.size());

 out.write(byteStream.toByteArray());
 
 out.flush();
 out.close();

 }
 
 @Override
 protected void doGet(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException {
 processRequest(request, response);
 }

 @Override
 protected void doPost(HttpServletRequest request, HttpServletResponse response)
 throws ServletException, IOException {
 processRequest(request, response);
 }

 @Override
 public String getServletInfo() {
 return "Short description";
 }
}
</pre>



Note that this servlet uses WebServlet annotation in line 17 above to declare the servlet instead of updating the web.xml descriptor.



From your JSF or HTML page call the servlet similar to shown below:



<pre class="brush: xml">
&lt;!-- storm below should be your application name -->
&lt;img src="/storm/ImageDownloader?image_url=http://somewhere.com/image.gif&type=gif" />
</pre>




That's it Good Luck.

Download and crop an image direct from a servlet