Image Resizing Servlet

ImageResizer.java

package com.photo.gallery;

import java.awt.AlphaComposite;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;

import javax.imageio.ImageIO;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class ImageResizer extends HttpServlet {
    /**
     * Servlet resizes an image located in a directory in a web project ex.
     * /image?root=/albums&file=/thumbs/imagename.jpg&width=270&height=100 ex.
     * /image?file=/thumbs/imagename.jpg&width=270 (default root, calculated
     * height)
     */
    private static final long serialVersionUID = -8285774993751841288L;

    public void doGet(HttpServletRequest request, HttpServletResponse response) {
        // Optional: Only supports output of jpg and png, defaults to png if not
        // specified
        String imageOutput = getParam(request, "output", "png");
        // Optional: Folder in web app where images are located, defaults to
        // albums if not specified
        String imageRoot = getParam(request, "root", "/albums");
        // Required: Path from root to image, including filename
        String imageFile = getParam(request, "file", "/Album1/image1.jpg");
        // Required: Width image should be resized to
        int width = Integer.parseInt(getParam(request, "width", "250"));
        // Optional: If specified used, otherwise proportions are calculated
        int height = Integer.parseInt(getParam(request, "width", "0"));

        // Set the mime type of the image
        if ("png".equals(imageOutput))
            response.setContentType("image/png");
        else
            response.setContentType("image/jpeg");

        // Server Location of the image
        String imageLoc = request.getSession().getServletContext().getRealPath(imageRoot) + imageFile;

        try {
            // Read the original image from the Server Location
            BufferedImage bufferedImage = ImageIO.read(new File(imageLoc));
            // Calculate the new Height if not specified
            int calcHeight = height > 0 ? height : (width * bufferedImage.getHeight() / bufferedImage.getWidth());
            // Write the image
            ImageIO.write(createResizedCopy(bufferedImage, width, calcHeight), imageOutput, response.getOutputStream());
        } catch (Exception e) {
            log("Problem with image: " + imageLoc + e);
        }
    }

    BufferedImage createResizedCopy(Image originalImage, int scaledWidth, int scaledHeight) {
        BufferedImage scaledBI = new BufferedImage(scaledWidth, scaledHeight, BufferedImage.TYPE_INT_RGB);
        Graphics2D g = scaledBI.createGraphics();
        g.setComposite(AlphaComposite.Src);
        g.drawImage(originalImage, 0, 0, scaledWidth, scaledHeight, null);
        g.dispose();
        return scaledBI;
    }

    // Check the param if it's not present return the default
    private String getParam(HttpServletRequest request, String param, String def) {
        String parameter = request.getParameter(param);
        if (parameter == null || "".equals(parameter)) {
            return def;
        } else {
            return parameter;
        }
    }
}

web.xml

<servlet>
  <servlet-name>image</servlet-name>
  <servlet-class>com.photo.gallery.ImageResizer</servlet-class>
  <load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
  <servlet-name>image</servlet-name>
  <url-pattern>/image</url-pattern>
</servlet-mapping>

x-result.html

<img src="/image?root=/albums&file=/thumbs/imagename.jpg&width=270&height=100">
<img src="/image?file=/thumbs/imagename.jpg&width=270 ">