org.jsecurity.web.servlet
Class OncePerRequestFilter

java.lang.Object
  org.jsecurity.web.servlet.ServletContextSupport
      org.jsecurity.web.servlet.OncePerRequestFilter

All Implemented Interfaces:

Filter, Nameable

Direct Known Subclasses:

AdviceFilter, JSecurityFilter

public abstract class OncePerRequestFilter
extends ServletContextSupport
implements Filter, Nameable

Filter base class that guarantees to be just executed once per request, on any servlet container. It provides a doFilterInternal(javax.servlet.ServletRequest, javax.servlet.ServletResponse, 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.

NOTE This class was borrowed from the Spring framework, and as such, all copyright notices and author names have remained in tact.

Since:

0.1

Author:

Les Hazlewood, Juergen Hoeller

Field Summary

static String	ALREADY_FILTERED_SUFFIX Suffix that gets appended to the filter name for the "already filtered" request attribute.
protected FilterConfig	filterConfig FilterConfig provided by the Servlet container at startup.

Constructor Summary

OncePerRequestFilter()

Method Summary

void	destroy() Default no-op implementation that can be overridden by subclasses for custom cleanup behavior.
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(ServletRequest request, ServletResponse response, FilterChain filterChain) Same contract as for doFilter, but guaranteed to be just invoked once per request.
protected String	getAlreadyFilteredAttributeName() Return name of the request attribute that identifies that a request has already been filtered.
FilterConfig	getFilterConfig() Returns the servlet container specified FilterConfig instance provided at startup.
protected String	getName() Returns the name of this filter.
void	init(FilterConfig filterConfig) Sets the filter's filterConfig and then immediately calls onFilterConfigSet() to trigger any processing a subclass might wish to perform.
protected void	onFilterConfigSet() Template method to be overridden by subclasses to perform initialization logic at startup.
void	setFilterConfig(FilterConfig filterConfig) Sets the FilterConfig and the ServletContext as attributes of this class for use by subclasses.
void	setName(String name) Sets the filter's name.
protected boolean	shouldNotFilter(ServletRequest request) Can be overridden in subclasses for custom filtering control, returning true to avoid filtering of the given request.

Methods inherited from class org.jsecurity.web.servlet.ServletContextSupport

bind, getAttribute, getContextInitParam, getServletContext, removeAttribute, setAttribute, 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

filterConfig

protected FilterConfig filterConfig

FilterConfig provided by the Servlet container at startup.

Constructor Detail

OncePerRequestFilter

public OncePerRequestFilter()

Method Detail

getFilterConfig

public FilterConfig getFilterConfig()

Returns the servlet container specified FilterConfig instance provided at startup.

Returns:

the servlet container specified FilterConfig instance provided at startup.

setFilterConfig

public void setFilterConfig(FilterConfig filterConfig)

Sets the FilterConfig and the ServletContext as attributes of this class for use by subclasses. That is:

this.filterConfig = filterConfig;
setServletContext(filterConfig.getServletContext());

Parameters:

filterConfig - the FilterConfig instance provided by the Servlet container at startup.

getName

protected String getName()

Returns the name of this filter.

Unless overridden by calling the setName(String) method, this value defaults to the filter name as specified by the servlet container at startup:

this.name = getFilterConfig().getName();

Returns:

the filter name, or null if none available

See Also:

GenericServlet.getServletName(), FilterConfig.getFilterName()

setName

public void setName(String name)

Sets the filter's name.

Unless overridden by calling this method, this value defaults to the filter name as specified by the servlet container at startup:

this.name = getFilterConfig().getName();

Specified by:

setName in interface Nameable

Parameters:

name - the name of the filter.

init

public final void init(FilterConfig filterConfig)
                throws ServletException

Sets the filter's filterConfig and then immediately calls onFilterConfigSet() to trigger any processing a subclass might wish to perform.

Specified by:

init in interface Filter

Parameters:

filterConfig - the servlet container supplied FilterConfig instance.

Throws:

ServletException - if onFilterConfigSet() throws an Exception.

onFilterConfigSet

protected void onFilterConfigSet()
                          throws Exception

Template method to be overridden by subclasses to perform initialization logic at startup. The ServletContext and FilterConfig will be accessible (and non-null) at the time this method is invoked via the getServletContext() and getFilterConfig() methods respectively.

Throws:

Exception - if the subclass has an error upon initialization.

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.

Specified by:

doFilter in interface Filter

Throws:

ServletException

IOException

See Also:

getAlreadyFilteredAttributeName(), shouldNotFilter(javax.servlet.ServletRequest), doFilterInternal(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)

getAlreadyFilteredAttributeName

protected String getAlreadyFilteredAttributeName()

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

The default implementation takes the configured name and appends ".FILTERED". If the filter is not fully initialized, it falls back to the implementation's class name.

Returns:

the name of the request attribute that identifies that a request has already been filtered.

See Also:

getName(), ALREADY_FILTERED_SUFFIX

shouldNotFilter

protected boolean shouldNotFilter(ServletRequest 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(ServletRequest request,
                                         ServletResponse 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

destroy

public void destroy()

Default no-op implementation that can be overridden by subclasses for custom cleanup behavior.

Specified by:

destroy in interface Filter