Why does Tomcat resolve context path differently for certain url-mappings?

Question

So, I'm trying to write a servlet which can handle a url mapping like:

domain/context/servlet/resource_id

Before, when I was specifying the url pattern, I was just doing:

/myServlet

But, for what I'm trying to accomplish, I'm doing...

/myServlet/*

THE PROBLEM I'M RUNNING INTO:

I've been using relative path (so, just the file location with respect to my WebContent folder) for my static files (css/js/etc) now that I'm using the /myServlet/* mapping, the requests for the all static files are now being handled by myServlet. So, basically, the static resources are now resolving to:

domain/context/myServlet/relative_path_I_provide

as opposed to

domain/context/relative_path_I_provide

I'm sure I can fix this myself by just building the absolute path for the resource as opposed to relying on the relative path; but I'm just wondering, why is the resolved path for the static resource changing when I'm using /myServlet/* url pattern as opposed to /myServlet ?

EDIT:

My folder structure is like

WebContent
   |
   |
   |-- debug
         |
         |-- css
              |
              |-- file.css

and I'm adding them in a link tag like:

<link href="debug/css/file.css" rel="stylesheet" type="text/css">

Answer 1

Ok, that explains it. You're using a relative URL with no path information which means the browser resolves it to same directory as the resource that includes these URLs. When your servlet was mapped to /myServlet, it didn't appear in the path as a 'directory' i.e. it was the final resource being referred to.

Thus, your URL for the servlet was of the form domain/context/myServlet and so these relative URLs would also resolve to domain/context/.

But now, with a mapping of the form /myServlet/*, the servlet appears as a directory in the URL which means that when you go to domain/context/myServlet/resource_id, the relative URLs are resolved to the same directory as resource_id which is domain/context/servlet/.

See this for more

The fix might be one of the following:

1. Use relative URLs that are relative to the root of the application i.e. which begin with /. However, this would require you to put in the context path for your application in your code which means you can never simply deploy it with a different name without having to change everything. In short, don't do this.

2. Use relative URLs with path information in the form of ../ which will cause the URLs to resolve to a directory one level up. This is also brittle and will break if someone decides to map the resources to URLs of the form domain/context/myServlet/secondLevel/resource_id.

3. Create relative URLs that are relative to the context-path of the application. You can do this by setting your href values as request.getContextPath + "/css/files/file.css". This will prepend the context-path to the beginning of each link's href thus, for request for domain/context/myServlet/resource_id, this will become /context/css/files/file.css and resolve as you expect.

Answer 2

Has your actual URL changed before and after the url pattern change? i.e. are you now invoking http://domain/context/myServlet/something instead of http://domain/context/myServlet

If the answer is yes, then it explains why the static files are now resolving to http://domain/context/myServlet/static_file
(For the same reason why everything was resolving relative to the context in the earlier URL)