This week's book giveaway is in the OO, Patterns, UML and Refactoring forum. We're giving away four copies of Refactoring for Software Design Smells: Managing Technical Debt and have Girish Suryanarayana, Ganesh Samarthyam & Tushar Sharma on-line! See this thread for details.
In your servlet you need to change the mime type to the proper type for your image. For example, for a PNG you would use:
where response is a javax.servlet.http.HttpServlteResponse (one of the parameters to doPost(), doGet() etc.)
You can find a partial list of mime types in ./server/default/deployers/jbossweb.deployer/web.xml (AS 5.1.0 location)