How can a filter be mapped to the root of a URL? I'm using Tomcat 7.0.2 and deploying an application as ROOT.war. The welcome page is sign_in.xhtml. I would like to run a filter whenever the client sends a request for the root of the site (i.e. the domain name only), or when the the client requests sign_in.xhtml. Here is what I have so far:
<filter>
<filter-name>My filter</filter-name>
<filter-class>com.myApp.myFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>My filter</filter-name>
<url-pattern>/sign_in.xhtml</url-pattern>
</filter-mapping>
Requests for sign_in.xhtml directly, successfully invoke the filter, but I'm not sure how to get requests for the root to invoke the filter. According to the Servlet spec (version 3.0)
<url-pattern>/</url-pattern>
maps to the default servlet, and an empty string maps to the root. Here's the relevant section from the spec:
"The empty string ("") is a special URL pattern that exactly maps to the
application's context root, i.e., requests of the form http://host:port//. In this case the path info is ’/’ and the servlet path and context path is
empty string (““)."
However, both of the following url patterns cause Tomcat to throw an exception.
<url-pattern></url-pattern>
<url-pattern>""</url-pattern>
I would really appreciate it if someone could shed some light on this. Thank You.
Andrew
Best Answer
The
<url-pattern>/</url-pattern>
should work for requests on the root. Did you try it?If your intent is more to filter all requests, then you should use
<url-pattern>/*</url-pattern>
.Update: To exclude one and other, I tested the
url-pattern
of/
at Tomcat 7 (using bothweb.xml
and@WebFilter(urlPatterns={"/"})
) and it indeed didn't work as expected. Theurl-pattern
of/
however works as expected on Tomcat 6 (Servlet 2.5) and also on Glassfish v3 (Servlet 3.0). I suspect a bug in Tomcat 7, so I've reported issue 49914 about this.