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java.lang.Object org.apache.log4j.spi.Filter
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.
Field Summary | |
---|---|
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
Deprecated. As of 1.2.12, use getNext() and setNext(org.apache.log4j.spi.Filter) instead |
Constructor Summary | |
---|---|
Filter()
|
Method Summary | |
---|---|
void |
activateOptions()
Usually filters options become active when set. |
abstract int |
decide(LoggingEvent event)
If the decision is DENY , then the event will be
dropped. |
Filter |
getNext()
Return the pointer to the next filter; |
void |
setNext(Filter next)
Set the next filter pointer. |
Methods inherited from class java.lang.Object |
---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
Field Detail |
---|
public Filter next
getNext()
and setNext(org.apache.log4j.spi.Filter)
instead
public static final int DENY
public static final int NEUTRAL
public static final int ACCEPT
Constructor Detail |
---|
public Filter()
Method Detail |
---|
public void activateOptions()
activateOptions
in interface OptionHandler
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.
public void setNext(Filter next)
public Filter getNext()
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