Question

In development I use jetty as the servlet container. I have the following development configuration:

• master project which has wabapp directory
• derived project which overrides some of the files in webapp directory

The master project webapp can be started in development mode thanks to providing appropriate WebAppContext to jetty.

Now I want to start derived project analogously, assuming that when request is made, there is an attempt to:

• get resource from webapp directory of derived project
• if it does not exists, get it from webapp directory of master project

I know that it is possible to override WebAppContext#getResource() method, however some libraries we use in the project seem to perform IO operations on wabapp directory on their own. For example by calling ServletContext#getRealPath("/"), and then reading files without use of ServletContext#getResource() method. The problem could be solved on lower level by some virtual file system on top of File, however it does not seem to be supported in JDK 1.6, any suggestions?

Answer 1

It seems that using something like ResourceCollection is sufficient:

http://download.eclipse.org/jetty/stable-7/apidocs/org/eclipse/jetty/util/resource/ResourceCollection.html

Unfortunately the GWT’s DevMode which I use is based on jetty 6, where ResourceCollection is unavailable. I extended the Resource class myself, and together with own GWT JettyLauncher, and thanks to small trick with setting resourceBase on DefaultServlet via reflection, I was able to serve webapp from two directories simultaneously.

protected void doStart() throws Exception {
    setClassLoader(new LauncherWebAppClassLoader());
    super.doStart();
    ServletHolder holder = getServletHandler().getServlet("default");
    Servlet servlet = holder.getServlet();
    Field field = servlet.getClass().getDeclaredField("_resourceBase");
    field.setAccessible(true);
    field.set(servlet, combinedResourceBase);
}