Servlet::Filter(3)

NAME
Servlet::Filter - filter interface

SYNOPSIS
  $filter->setFilterConfig($fconfig);

  # later

  $filter->doFilter($request, $response, $chain);

  my $config = $filter->getConfig();

DESCRIPTION
This is the interface for an object that performs filtering tasks on the request for a resource, the response, or both.

Filters perform filtering in the "doFilter()" method. Every filter has access to a Servlet::FilterConfig object from which it can obtain its initialization parameters and a reference to the Servlet::ServletContext which it can use, for example, to load resources needed for filtering tasks.

Filters are configured in the deployment descriptor of a web application.

Examples that have been identified for this design are:

Authentication Filters
Logging and Auditing Filters
Image conversion Filters
Data compression Filters
Encryption Filters
Tokenizing Filters
Filters that trigger resource access events
XSL/T Filters
MIME-type chain Filters

METHODS

doFilter($request, $response, $chain)
    This method is called by the container each time a request/response pair is passed through the filter chain due to a client request for a resource at the end of the chain. The filter chain passed into this method allows the filter to passon the request and response to the next entity in the chain.

    A typical implementation of this method would follow such a pattern:

    1   Examine the request

    2   Optionally wrap the request object with a custom implementation to filter content or headers for input filtering

    3   Optionally wrap the response object with a custom implementation to filter content or headers for output filtering

    4 a)
        Either invoke the next entity in the chain by calling "doFilter()" on $chain,

    4 b)
        or block further filter processing by not passing the request/response pair down the chain

    5   Directly set headers on the response after invocation of the next entity in the filter chain.

    Parameters:

    $request
        the Servlet::ServletRequest object that contains the client's request

    $response
        the Servlet::ServletResponse object that contains the servlet's response

    $chain
        the Servlet::FilterChain through which the request and response are passed

    Throws:

    Servlet::ServletException
        if an exception occurs while performing the filtering task

getFilterConfig()
    Returns the Servlet::FilterConfig object for this filter

setFilterConfig($config)
    Set the config object for this filter

    Parameters:

    $config
        the Servlet::FilterConfig object for this filter

SEE ALSO
Servlet::FilterChain, Servlet::FilterConfig, Servlet::ServletException, Servlet::ServletRequest, Servlet::ServletResponse

AUTHOR
Brian Moseley, bcm@maz.org