org.apache.log4j.filter
Class ExpressionFilter

java.lang.Object
  org.apache.log4j.spi.Filter
      org.apache.log4j.filter.ExpressionFilter

All Implemented Interfaces:

org.apache.log4j.spi.OptionHandler

public class ExpressionFilter
extends org.apache.log4j.spi.Filter

A filter supporting complex expressions - supports both infix and postfix expressions (infix expressions must first be converted to postfix prior to processing).

See org.apache.log4j.chainsaw.LoggingEventFieldResolver.java for the correct names for logging event fields used when building expressions.

See org.apache.log4j.chainsaw.rule package for a list of available rules which can be applied using the expression syntax.

See org.apache.log4j.chainsaw.RuleFactory for the symbols used to activate the corresponding rules.

NOTE: Grouping using parentheses is supported - all tokens must be separated by spaces, and operands which contain spaces are not yet supported.

Example:

In order to build a filter that displays all messages with infomsg-45 or infomsg-44 in the message, as well as all messages with a level of WARN or higher, build an expression using the LikeRule (supports java.util.regex based regular expressions) and the InequalityRule. ( MSG LIKE infomsg-4[4,5] ) && ( LEVEL >= WARN )

Three options are required: Expression - the expression to match ConvertInFixToPostFix - convert from infix to posfix (default true) AcceptOnMatch - true or false (default true)

Meaning of AcceptToMatch: If there is a match between the value of the Expression option and the LoggingEvent and AcceptOnMatch is true, the decide(org.apache.log4j.spi.LoggingEvent) method returns Filter.ACCEPT.

If there is a match between the value of the Expression option and the LoggingEvent and AcceptOnMatch is false, Filter.DENY is returned.

If there is no match, Filter.NEUTRAL is returned.

Author:

Scott Deboy sdeboy@apache.org

Field Summary

Fields inherited from class org.apache.log4j.spi.Filter

ACCEPT, DENY, NEUTRAL, next

Constructor Summary

ExpressionFilter()

Method Summary

void	activateOptions()
int	decide(org.apache.log4j.spi.LoggingEvent event) Determines if event matches the filter.
boolean	getAcceptOnMatch() Gets whether filter accepts matching or non-matching events.
boolean	getConvertInFixToPostFix() Get in-fix to post-fix conversion setting.
java.lang.String	getExpression() Get expression.
void	setAcceptOnMatch(boolean newValue) Set whether filter should accept events if they match the expression.
void	setConvertInFixToPostFix(boolean newValue) Set convert in-fix to post-fix.
void	setExpression(java.lang.String exp) Set exp.

Methods inherited from class org.apache.log4j.spi.Filter

getNext, setNext

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ExpressionFilter

public ExpressionFilter()

Method Detail

activateOptions

public void activateOptions()

Specified by:

activateOptions in interface org.apache.log4j.spi.OptionHandler

Overrides:

activateOptions in class org.apache.log4j.spi.Filter

setExpression

public void setExpression(java.lang.String exp)

Set exp.

Parameters:

exp - exp.

getExpression

public java.lang.String getExpression()

Get expression.

Returns:

expression.

setConvertInFixToPostFix

public void setConvertInFixToPostFix(boolean newValue)

Set convert in-fix to post-fix.

Parameters:

newValue - new value.

getConvertInFixToPostFix

public boolean getConvertInFixToPostFix()

Get in-fix to post-fix conversion setting.

Returns:

true if in-fix expressions are converted to post-fix.

setAcceptOnMatch

public void setAcceptOnMatch(boolean newValue)

Set whether filter should accept events if they match the expression.

Parameters:

newValue - if true, accept on match.

getAcceptOnMatch

public boolean getAcceptOnMatch()

Gets whether filter accepts matching or non-matching events.

Returns:

if true, accept matching events.

decide

public int decide(org.apache.log4j.spi.LoggingEvent event)

Determines if event matches the filter.

Specified by:

decide in class org.apache.log4j.spi.Filter

Parameters:

event - logging event;

Returns:

Filter.NEUTRAL is there is no string match.