WebSphere 7: Modify HTTP headers for static content file serving

Question

I'm using the <enable-file-serving value="true" /> feature of WebSphere Application Server v7.0 to serve static content (images, CSS, JavaScripts) for my Java web app.

How can I modify the HTTP headers for this static content (e.g., add a Cache-Control or Expires header)?

Answer 1

I ended up writing a Filter to add the HTTP header based on the URL of the requested resource. Here's a simplified version:

CacheFilter.java

public class CacheFilter implements Filter {
    private static long maxAge = 86400 * 30; // 30 days in seconds

    @Override
    public void doFilter(ServletRequest request, ServletResponse response,
            FilterChain chain) throws IOException, ServletException {
        HttpServletResponse httpResponse = (HttpServletResponse) response;
        httpResponse.setHeader("Cache-Control", "max-age=" + maxAge);
        chain.doFilter(request, response);
    }

    @Override
    public void init(FilterConfig filterConfig) throws ServletException {
    }

    @Override
    public void destroy() {
    }
}

web.xml

<filter>
    <filter-name>cache</filter-name>
    <filter-class>com.example.CacheFilter</filter-class>
</filter>
<filter-mapping>
    <filter-name>cache</filter-name>
    <url-pattern>*.png</url-pattern>
</filter-mapping>
<filter-mapping>
    <filter-name>cache</filter-name>
    <url-pattern>*.jpg</url-pattern>
</filter-mapping>
<filter-mapping>
    <filter-name>cache</filter-name>
    <url-pattern>*.gif</url-pattern>
</filter-mapping>