A filter is a piece of re-usable code that can transform the contents of HTTP requests, responses, and header information by modifying requests to and responses from a servlet.
You create a filter by implementing the javax.servlet.Filter
interface
and providing a public constructor taking no arguments. The IDE provides a wizard
to help you create filters. The simple filter template helps you to create a
basic filter class, while the advanced filter template helps you to create a
more complex filter class with wrapper classes.
Filters are declared using the filter
element in the web module's deployment descriptor (web.xml
) and
packaged in a WAR file along with the static content and servlets that make
up a web module. A filter or collection of filters can be configured for invocation
by defining the filter-mapping
elements in the deployment descriptor.
To create a Filter:
You can also create a filter from within the Explorer. Right-click the location
where the filter will be stored (typically in WEB-INF/Classes
),
then choose New JSP & Servlet
Filters and the appropriate
filter template from the contextual menu.
For more information about filters, see the Java Servlet 2.3 Specification
available at http://java.sun.com/products/servlet
.
See Also | |
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Filters (defined) |