| java.lang.Object | |
| ↳ | org.apache.log4j.spi.Filter |
 Known Direct Subclasses
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Class Overview
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.
Summary
| Constants | |||||||||||
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| int | ACCEPT | The log event must be logged immediately without consulting with the remaining filters, if any, in the chain. | |||||||||
| int | DENY | The log event must be dropped immediately without consulting with the remaining filters, if any, in the chain. | |||||||||
| int | NEUTRAL | This filter is neutral with respect to the log event. | |||||||||
| Fields | |||||||||||
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| next |
This field is deprecated.
As of 1.2.12, use getNext() and setNext(Filter) instead
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| Public Methods | |||||||||||
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Usually filters options become active when set.
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If the decision is | |||||||||||
Return the pointer to the next filter;
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Set the next filter pointer.
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[Expand]
Inherited Methods | |||||||||||
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From class
java.lang.Object
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From interface
org.apache.log4j.spi.OptionHandler
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Constants
public static final int ACCEPT
The log event must be logged immediately without consulting with the remaining filters, if any, in the chain.
public static final int DENY
The log event must be dropped immediately without consulting with the remaining filters, if any, in the chain.
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.
Fields
public Filter next
This field is deprecated.
As of 1.2.12, use getNext() and setNext(Filter) instead
Points to the next filter in the filter chain.
Public Constructors
public Filter ()
Public Methods
public void activateOptions ()
Usually filters options become active when set. We provide a default do-nothing implementation for convenience.
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.
Parameters
| event | The LoggingEvent to decide upon. |
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Returns
- decision The decision of the filter.