tomcat如何设置静态文件的过期头

tomcat如何设置静态文件的过期头

我准备使用squid2.6+tomcat6为用户提供web服务器,在tomcat里如何设置静态文件(html、gif、js等)的过期头?
Write own code to set HTTP header is a possible way. If you don't want to write some code, you can add content.xml file into the special directory.