Implementation verified on both Tomcat and GlassFish v3.

Current code contains:

InputStream fileStream = session.getServletContext().getResourceAsStream(filePath);

which causes the creation of a session just for serving resources. This should be optimized
by implementing ServletContextAware and obtaining the ServletContext without the HttpSession reference.

(Even better would be to add getServletContext() to ServletRequest.)

Spring DispatcherServlet is mapped to "/" to provide REST URLs in the application, but this interferes with default static resource serving:

<servlet>
<servlet-name>chat</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
<servlet-name>chat</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>

It is possible to map *.jpg, *.css to the Servlet named "default", but this is only provided by Tomcat.

A portable method should use Spring dispatch.