org.apache.log4j.spi
Class Filter
- OptionHandler
public abstract class Filter
Users should extend this class to implement customized logging
event filtering. Note that
Category
and
AppenderSkeleton
, the parent class of all standard
appenders, have built-in filtering rules. It is suggested that you
first use and understand the built-in rules before rushing to write
your own custom filters.
This abstract class assumes and also imposes that filters be
organized in a linear chain. The
decide(LoggingEvent)
method of each filter is called sequentially,
in the order of their addition to the chain.
The
decide(LoggingEvent)
method must return one
of the integer constants
DENY
,
NEUTRAL
or
ACCEPT
.
If the value
DENY
is returned, then the log event is
dropped immediately without consulting with the remaining
filters.
If the value
NEUTRAL
is returned, then the next filter
in the chain is consulted. If there are no more filters in the
chain, then the log event is logged. Thus, in the presence of no
filters, the default behaviour is to log all logging events.
If the value
ACCEPT
is returned, then the log
event is logged without consulting the remaining filters.
The philosophy of log4j filters is largely inspired from the
Linux ipchains.
Note that filtering is only supported by the
DOMConfigurator
. The
PropertyConfigurator
does not
support filters.
static int | ACCEPT - The log event must be logged immediately without consulting with
the remaining filters, if any, in the chain.
|
static int | DENY - The log event must be dropped immediately without consulting
with the remaining filters, if any, in the chain.
|
static int | NEUTRAL - This filter is neutral with respect to the log event.
|
Filter | next - As of 1.2.12, use
getNext() and setNext(Filter) instead
|
ACCEPT
public static final int ACCEPT
The log event must be logged immediately without consulting with
the remaining filters, if any, in the chain.
DENY
public static final int DENY
The log event must be dropped immediately without consulting
with the remaining filters, if any, in the chain.
NEUTRAL
public static final int NEUTRAL
This filter is neutral with respect to the log event. The
remaining filters, if any, should be consulted for a final decision.
activateOptions
public void activateOptions()
Usually filters options become active when set. We provide a
default do-nothing implementation for convenience.
- activateOptions in interface OptionHandler
decide
public abstract int decide(LoggingEvent event)
If the decision is DENY
, then the event will be
dropped. If the decision is NEUTRAL
, then the next
filter, if any, will be invoked. If the decision is ACCEPT then
the event will be logged without consulting with other filters in
the chain.
event
- The LoggingEvent to decide upon.
- decision The decision of the filter.
getNext
public Filter getNext()
Return the pointer to the next filter;
setNext
public void setNext(Filter next)
Set the next filter pointer.
Copyright 2000-2005 Apache Software Foundation.