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 filter template helps you to create a basic
filter class, while the wrapping filter template helps you to create a filter
class that wraps the Request and Response objects prior to passing on the request.
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:
For more information about filters, see the Java Servlet Specification
available at http://java.sun.com/products/servlet
.
See Also | |
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Filters (defined) |