Package javax.portlet.filter
Interface ActionFilter
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- All Superinterfaces:
PortletFilter
public interface ActionFilter extends PortletFilter
TheActionFilter
is an object that performs filtering tasks on either the action request to a portlet, or on the action response from a portlet, or both.Filters perform filtering in the
doFilter
method. Every Filter has access to aFilterConfig
object from which it can obtain its initialization parameters, a reference to the PortletContext which it can use, for example, to load resources needed for filtering tasks.Filters are configured in the portlet deployment descriptor of a portlet application.
- Since:
- 2.0
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description void
doFilter(ActionRequest request, ActionResponse response, FilterChain chain)
ThedoFilter
method of the Filter is called by the portlet container each time a action request/response pair is passed through the chain due to a client request for a portlet method at the end of the chain.-
Methods inherited from interface javax.portlet.filter.PortletFilter
destroy, init
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Method Detail
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doFilter
void doFilter(ActionRequest request, ActionResponse response, FilterChain chain) throws java.io.IOException, PortletException
ThedoFilter
method of the Filter is called by the portlet container each time a action request/response pair is passed through the chain due to a client request for a portlet method at the end of the chain.The
FilterChain
passed in to this method allows the Filter to pass on the action request and response to the next component in the chain.The
doFilter
method of a filter will typically be implemented following this or some subset of the following pattern:- The method examines the request information.
- The method may wrap the request object passed in to
its doFilter method with a customized implementation
the request wrapper
ActionRequestWrapper
in order to modify request data. - The method may wrap the response object passed in to its
doFilter
method with a customized implementation of the response wrapperActionResponseWrapper
to modify response data. - The filter may invoke the next component in the filter chain.
The next component may be another filter, or if the filter
making the invocation is the last filter configured in the
deployment descriptor for this chain, the next component
is the target method of the portlet. The invocation of the
next component is effected by calling the
doFilter
method on theFilterChain
object, and passing in the request and response with which it was called or passing in wrapped versions it may have created. The filter chain's implementation of thedoFilter
method, provided by the portlet container, must locate the next component in the filter chain and invoke itsdoFilter
method, passing in the appropriate request and response objects. Alternatively, the filter chain can block the request by not making the call to invoke the next component, leaving the filter responsible for filling out the response object. - After invocation of the next filter in the chain, the filter may examine the response data.
- Alternatively, the filter may have thrown an exception to
indicate an error in processing. If the filter throws an
UnavailableException
during itsdoFilter
processing, the portlet container must not attempt continued processing down the filter chain. It may choose to retry the whole chain at a later time if the exception is not marked permanent. - When the last filter in the chain has been invoked, the next component accessed is the target method on the portlet at the end of the chain.
- Parameters:
request
- the current action requestresponse
- the current action responsechain
- the remaining filter chain- Throws:
java.io.IOException
- if an IO error occurred in the filter processingPortletException
- if a portlet exception occurred in the filter processing
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