Question

I’m setting up a web app on GlassFish and I’m wondering if there is a way to configure servlet mapping from the URL root to only apply in cases where a file or directory doesn’t exist at the specified URL.

Currently, this will route everything through my Spring dispatcher:

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/javaee"
           xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
           xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
    http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd"
           version="3.0">
 <servlet>
  <servlet-name>dispatcher</servlet-name>
  <servlet-class>
   org.springframework.web.servlet.DispatcherServlet
  </servlet-class>
  <load-on-startup>1</load-on-startup>
 </servlet>
 <servlet-mapping>
  <servlet-name>dispatcher</servlet-name>
  <url-pattern>/</url-pattern>
 </servlet-mapping>
 <welcome-file-list>
  <welcome-file>
   /jsp/index.jsp
  </welcome-file>
 </welcome-file-list>
</web-app>

Is it somehow possible to preserve the above behavior unless a file or directory exists at a given path? Am I trying to solve this problem in the wrong place?

UPDATE: What about URL rewriting? Does GlassFish provide any degree of flexibility like Apache does with mod_rewrite? That way I could intercept things before it even reaches the servlet mapping stage.

Answer 1

Hacky, but doable: map it as <error-page> on an <error-code> of 404.

<servlet>
    <servlet-name>errorServlet</servlet-name>
    <servlet-class>com.example.ErrorServlet</servlet-class>
</servlet>
<servlet-mapping>
    <servlet-name>errorServlet</servlet-name>
    <url-pattern>/error</url-pattern>
</servlet-mapping>

<error-page>
    <error-code>404</error-code>
    <location>/error</location>
</error-page>

You might want to change the status code in the servlet whenever you want to return a “valid” response.

An alternative is to let the Spring servlet listen on a more specific url-pattern. E.g. /pages/*. You could then if necessary bring a Filter in front (on /*) which does roughly the following:

if (new File(servletContext.getRealPath(request.getRequestURI())).exists()) {
    chain.doFilter(request, response);
} else {
    request.getRequestDispatcher("/pages" + request.getRequestURI()).forward(request, response);
}

so that you don’t see/need /pages in the URL.

---

Update: as per your new question:

UPDATE: What about URL rewriting? Does GlassFish provide any degree of flexibility like Apache does with mod_rewrite? That way I could intercept things before it even reaches the servlet mapping stage.

The JSP/Servlet equivalent of Apache HTTPD’s mod_rewrite addon is the Tuckey’s UrlRewriteFilter.