Apache log4cxx  Version 0.13.0
log4cxx::spi::Filter Class Referenceabstract

Users should extend this class to implement customized logging event filtering. More...

#include <filter.h>

Inheritance diagram for log4cxx::spi::Filter:
log4cxx::spi::OptionHandler log4cxx::helpers::Object log4cxx::helpers::Object log4cxx::filter::AndFilter log4cxx::filter::DenyAllFilter log4cxx::filter::ExpressionFilter log4cxx::filter::LevelMatchFilter log4cxx::filter::LevelRangeFilter log4cxx::filter::LocationInfoFilter log4cxx::filter::LoggerMatchFilter log4cxx::filter::MapFilter log4cxx::filter::PropertyFilter log4cxx::filter::StringMatchFilter

Public Types

enum  FilterDecision { DENY = -1, NEUTRAL = 0, ACCEPT = 1 }

Public Member Functions

 Filter ()
log4cxx::spi::FilterPtr getNext () const
void setNext (const log4cxx::spi::FilterPtr &newNext)
void activateOptions (log4cxx::helpers::Pool &p)
 Usually filters options become active when set. More...
void setOption (const LogString &option, const LogString &value)
 Set option to value. More...
virtual FilterDecision decide (const LoggingEventPtr &event) const =0
- Public Member Functions inherited from log4cxx::spi::OptionHandler
virtual ~OptionHandler ()
- Public Member Functions inherited from log4cxx::helpers::Object
virtual ~Object ()
virtual bool instanceof (const Class &clazz) const =0
virtual const void * cast (const Class &clazz) const =0

Detailed Description

Users should extend this class to implement customized logging event filtering.

Note that Logger 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 log4cxx filters is largely inspired from the Linux ipchains.

Note that filtering is only supported by the DOMConfigurator.

Member Enumeration Documentation

◆ FilterDecision


The log event must be dropped immediately without consulting with the remaining filters, if any, in the chain.


This filter is neutral with respect to the log event.

The remaining filters, if any, should be consulted for a final decision.


The log event must be logged immediately without consulting with the remaining filters, if any, in the chain.

Constructor & Destructor Documentation

◆ Filter()

log4cxx::spi::Filter::Filter ( )

Member Function Documentation

◆ activateOptions()

void log4cxx::spi::Filter::activateOptions ( log4cxx::helpers::Pool p)

Usually filters options become active when set.

We provide a

default do-nothing implementation for convenience.

Implements log4cxx::spi::OptionHandler.

◆ decide()

virtual FilterDecision log4cxx::spi::Filter::decide ( const LoggingEventPtr event) const
pure virtual

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.

eventThe LoggingEvent to decide upon.
The decision of the filter.

Implemented in log4cxx::filter::LevelRangeFilter, log4cxx::filter::ExpressionFilter, log4cxx::filter::MapFilter, log4cxx::filter::AndFilter, log4cxx::filter::StringMatchFilter, log4cxx::filter::LoggerMatchFilter, log4cxx::filter::LevelMatchFilter, log4cxx::filter::LocationInfoFilter, log4cxx::filter::PropertyFilter, and log4cxx::filter::DenyAllFilter.

◆ getNext()

log4cxx::spi::FilterPtr log4cxx::spi::Filter::getNext ( ) const

◆ setNext()

void log4cxx::spi::Filter::setNext ( const log4cxx::spi::FilterPtr newNext)

◆ setOption()

void log4cxx::spi::Filter::setOption ( const LogString option,
const LogString value 

Set option to value.

The handling of each option depends on the OptionHandler instance. Some options may become active immediately whereas other may be activated only when activateOptions is called.

Implements log4cxx::spi::OptionHandler.

The documentation for this class was generated from the following file: