public abstract class AbstractFilter extends ServletContextSupport implements Filter
access
to init parameters.
Subclass initialization logic should be performed by overriding the onFilterConfigSet()
template method.
FilterChain execution logic (the
Filter.doFilter(javax.servlet.ServletRequest, javax.servlet.ServletResponse, javax.servlet.FilterChain)
method
is left to subclasses.Modifier and Type | Field and Description |
---|---|
protected FilterConfig |
filterConfig
FilterConfig provided by the Servlet container at start-up.
|
Constructor and Description |
---|
AbstractFilter() |
Modifier and Type | Method and Description |
---|---|
void |
destroy()
Default no-op implementation that can be overridden by subclasses for custom cleanup behavior.
|
FilterConfig |
getFilterConfig()
Returns the servlet container specified
FilterConfig instance provided at
startup . |
protected String |
getInitParam(String paramName)
Returns the value for the named
init-param , or null if there was no init-param
specified by that name. |
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 start-up.
|
void |
setFilterConfig(FilterConfig filterConfig)
Sets the FilterConfig and the
ServletContext as attributes of this class for use by
subclasses. |
getContextAttribute, getContextInitParam, getServletContext, removeContextAttribute, setContextAttribute, setServletContext, toString, toStringBuilder
protected FilterConfig filterConfig
public AbstractFilter()
public FilterConfig getFilterConfig()
FilterConfig
instance provided at
startup
.FilterConfig
instance provided at start-up.public void setFilterConfig(FilterConfig filterConfig)
ServletContext
as attributes of this class for use by
subclasses. That is:
this.filterConfig = filterConfig; setServletContext(filterConfig.getServletContext());
filterConfig
- the FilterConfig instance provided by the Servlet container at start-up.protected String getInitParam(String paramName)
init-param
, or null
if there was no init-param
specified by that name.paramName
- the name of the init-param
init-param
, or null
if there was no init-param
specified by that name.public final void init(FilterConfig filterConfig) throws ServletException
filterConfig
and then immediately calls
onFilterConfigSet()
to trigger any processing a subclass might wish to perform.init
in interface Filter
filterConfig
- the servlet container supplied FilterConfig instance.ServletException
- if onFilterConfigSet()
throws an Exception.protected void onFilterConfigSet() throws Exception
ServletContext
and FilterConfig
will be accessible
(and non-null
) at the time this method is invoked via the
getServletContext()
and getFilterConfig()
methods respectively.
init-param
values may be conveniently obtained via the getInitParam(String)
method.Exception
- if the subclass has an error upon initialization.Copyright © 2004-2016 The Apache Software Foundation. All Rights Reserved.