org.springframework.web.filter
Class OncePerRequestFilter

java.lang.Object
  org.springframework.web.filter.GenericFilterBean
      org.springframework.web.filter.OncePerRequestFilter

All Implemented Interfaces:

Filter, BeanNameAware, DisposableBean, InitializingBean, ServletContextAware

Direct Known Subclasses:

AbstractRequestLoggingFilter, CharacterEncodingFilter, MultipartFilter, OpenEntityManagerInViewFilter, OpenPersistenceManagerInViewFilter, OpenSessionInViewFilter, RequestContextFilter

public abstract class OncePerRequestFilter
extends GenericFilterBean

Filter base class that guarantees to be just executed once per request, on any servlet container. It provides a doFilterInternal(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, javax.servlet.FilterChain) method with HttpServletRequest and HttpServletResponse arguments.

The getAlreadyFilteredAttributeName() method determines how to identify that a request is already filtered. The default implementation is based on the configured name of the concrete filter instance.

Since:

06.12.2003

Author:

Juergen Hoeller

Field Summary

static String

ALREADY_FILTERED_SUFFIX Suffix that gets appended to the filter name for the "already filtered" request attribute.

Fields inherited from class org.springframework.web.filter.GenericFilterBean

logger

Constructor Summary

OncePerRequestFilter()

Method Summary

void	doFilter(ServletRequest request, ServletResponse response, FilterChain filterChain) This doFilter implementation stores a request attribute for "already filtered", proceeding without filtering again if the attribute is already there.
protected abstract void	doFilterInternal(HttpServletRequest request, HttpServletResponse response, FilterChain filterChain) Same contract as for doFilter, but guaranteed to be just invoked once per request.
protected String	getAlreadyFilteredAttributeName() Return the name of the request attribute that identifies that a request is already filtered.
protected boolean	shouldNotFilter(HttpServletRequest request) Can be overridden in subclasses for custom filtering control, returning true to avoid filtering of the given request.

Methods inherited from class org.springframework.web.filter.GenericFilterBean

addRequiredProperty, afterPropertiesSet, destroy, getFilterConfig, getFilterName, getServletContext, init, initBeanWrapper, initFilterBean, setBeanName, setServletContext

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

ALREADY_FILTERED_SUFFIX

public static final String ALREADY_FILTERED_SUFFIX

Suffix that gets appended to the filter name for the "already filtered" request attribute.

See Also:

getAlreadyFilteredAttributeName(), Constant Field Values

Constructor Detail

OncePerRequestFilter

public OncePerRequestFilter()

Method Detail

doFilter

public final void doFilter(ServletRequest request,
                           ServletResponse response,
                           FilterChain filterChain)
                    throws ServletException,
                           IOException

This doFilter implementation stores a request attribute for "already filtered", proceeding without filtering again if the attribute is already there.

Throws:

ServletException

IOException

See Also:

getAlreadyFilteredAttributeName(), shouldNotFilter(javax.servlet.http.HttpServletRequest), doFilterInternal(javax.servlet.http.HttpServletRequest, javax.servlet.http.HttpServletResponse, javax.servlet.FilterChain)

getAlreadyFilteredAttributeName

protected String getAlreadyFilteredAttributeName()

Return the name of the request attribute that identifies that a request is already filtered.

Default implementation takes the configured name of the concrete filter instance and appends ".FILTERED". If the filter is not fully initialized, it falls back to its class name.

See Also:

GenericFilterBean.getFilterName(), ALREADY_FILTERED_SUFFIX

shouldNotFilter

protected boolean shouldNotFilter(HttpServletRequest request)
                           throws ServletException

Can be overridden in subclasses for custom filtering control, returning true to avoid filtering of the given request.

The default implementation always returns false.

Parameters:

request - current HTTP request

Returns:

whether the given request should not be filtered

Throws:

ServletException - in case of errors

doFilterInternal

protected abstract void doFilterInternal(HttpServletRequest request,
                                         HttpServletResponse response,
                                         FilterChain filterChain)
                                  throws ServletException,
                                         IOException

Same contract as for doFilter, but guaranteed to be just invoked once per request. Provides HttpServletRequest and HttpServletResponse arguments instead of the default ServletRequest and ServletResponse ones.

Throws:

ServletException

IOException