Class Filter
- java.lang.Object
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- org.apache.log4j.spi.Filter
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- All Implemented Interfaces:
OptionHandler
- Direct Known Subclasses:
DenyAllFilter
,LevelMatchFilter
,LevelRangeFilter
,StringMatchFilter
public abstract class Filter extends Object implements OptionHandler
Users should extend this class to implement customized logging event filtering. Note thatCategory
andAppenderSkeleton
, 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 constantsDENY
,NEUTRAL
orACCEPT
.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
. ThePropertyConfigurator
does not support filters.- Since:
- 0.9.0
- Author:
- Ceki Gülcü
-
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Field Summary
Fields Modifier and Type Field Description 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, usegetNext()
andsetNext(org.apache.log4j.spi.Filter)
instead
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Constructor Summary
Constructors Constructor Description Filter()
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description void
activateOptions()
Usually filters options become active when set.abstract int
decide(LoggingEvent event)
If the decision isDENY
, then the event will be dropped.Filter
getNext()
Return the pointer to the next filter;void
setNext(Filter next)
Set the next filter pointer.
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Field Detail
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next
public Filter next
Deprecated.As of 1.2.12, usegetNext()
andsetNext(org.apache.log4j.spi.Filter)
insteadPoints to the next filter in the filter 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.- See Also:
- Constant Field Values
-
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.- See Also:
- Constant Field Values
-
ACCEPT
public static final int ACCEPT
The log event must be logged immediately without consulting with the remaining filters, if any, in the chain.- See Also:
- Constant Field Values
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Method Detail
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activateOptions
public void activateOptions()
Usually filters options become active when set. We provide a default do-nothing implementation for convenience.- Specified by:
activateOptions
in interfaceOptionHandler
-
decide
public abstract int decide(LoggingEvent event)
If the decision is
DENY
, then the event will be dropped. If the decision isNEUTRAL
, 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.- Parameters:
event
- The LoggingEvent to decide upon.- Returns:
- decision The decision of the filter.
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setNext
public void setNext(Filter next)
Set the next filter pointer.
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getNext
public Filter getNext()
Return the pointer to the next filter;
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