Question

My filter mapping in web.xml is as follows:

  <filter>
    <filter-name>LoginCheckFilter</filter-name>
    <filter-class>com.tutorial.filter.LoginCheckFilter</filter-class>
  </filter>
  <filter-mapping>
    <filter-name>LoginCheckFilter</filter-name>
    <url-pattern>/admin*</url-pattern>
  </filter-mapping>

When I run my app and hit http://localhost:8080/admin my filter is not getting executed. I’m not able to understand why.

Is there any problem with the pattern. Also If I remove '*' from the pattern then the filter is getting executed on hitting above url.

Need help on this. Thanks.

Answer 1

The specifications (paragraph 12.2) says the following:

In the Web application deployment descriptor, the following syntax is
used to define mappings:

• A string beginning with a ‘/’ character and
  ending with a ‘/*’ suffix is used for path mapping.

• A string
  beginning with a ‘*.’ prefix is used as an extension mapping.

• 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/<contextroot>/. In this case the path info is ’/’ and
  the servlet path and context path is empty string (““).

• A string
  containing only the ’/’ character indicates the “default” servlet of
  the application. In this case the servlet path is the request URI
  minus the context path and the path info is null.

• All other strings
  are used for exact matches only.

So the * is taken literally, unless the pattern ends with /* or starts with *.