Defines a filter alias for later mapping.

Tag	Meaning
filter-name	The filter's name (alias)
filter-class	The filter's class (defaults to servlet-name)
init-param	Initialization parameters

The following example defines a filter alias 'image'

<web-app id='/'> <filter-mapping url-pattern='/images/*' filter-name='image'/> <filter filter-name='image' filter-class='test.MyImage'> <init-param title='Hello, World'/> </servlet> </web-app>

Alias of the filter.

Class of the filter. The CLASSPATH for filters includes the WEB-INF/classes directory and all jars in the WEB-INF/lib directory.

Initializes filter variables. filter-param defines initial values for getFilterConfig().getInitParameter("foo").

The full Servlet 2.3 syntax for init-param is supported and allows a simple shortcut

<web-app id='/'> <filter filter-name='test.HelloWorld'> <init-param foo='bar'/> <init-param> <param-name>baz</param-name> <param-value>value</param-value> </init-param> </servlet> </web-app>

Maps url patterns to filters. filter-mapping has two children, url-pattern and filter-name. url-pattern selects the urls which should execute the filter.

filter-name can either specify a servlet class directly or it can specify a servlet alias defined by filter.

Configuration	Description
url-pattern	A pattern matching the url: /foo/*, /foo, or *.foo
url-regexp	A regular expression matching the url
servlet-name	A servlet name to match.
filter-name	The filter name
filter-class	The filter class
init-param	Initialization parameters

<caucho.com> <web-app id='/'> <servlet servlet-name='hello' servlet-class='test.HelloWorld'/> <servlet-mapping url-pattern='/hello' servlet-name='hello'/> <filter filter-name='test-filter' filter-class='test.MyFilter'/> <filter-mapping url-pattern='/hello/*' filter-name='test-filter'/> <filter-mapping servlet-name='hello' filter-name='test.SecondFilter'/> </web-app>