如何使用Java中的过滤器基于HTML文档输出二进制文档

This may be a little confusing but I having some trouble. My goal is to take an input HTML document and then process that document and use the HTML data to output a image document. For example, a user will request a URL, with some action=png in the querystring and then the filter will get invoked for the URL and output image document.This may be a little confusing but I having som