Class ExpressionRule

java.lang.Object

org.apache.log4j.rule.AbstractRule

org.apache.log4j.rule.ExpressionRule

All Implemented Interfaces:

Serializable, Rule

public class ExpressionRule
extends AbstractRule

A Rule class supporting both infix and postfix expressions, accepting any rule which is supported by the RuleFactory. NOTE: parsing is supported through the use of StringTokenizer, which implies two limitations: 1: all tokens in the expression must be separated by spaces, including parenthesis 2: operands which contain spaces MUST be wrapped in single quotes. For example, the expression: msg == 'some msg' is a valid expression. 3: To group expressions, use parentheses. For example, the expression: level >= INFO || ( msg == 'some msg' || logger == 'test' ) is a valid expression. See org.apache.log4j.rule.InFixToPostFix for a description of supported operators. See org.apache.log4j.spi.LoggingEventFieldResolver for field keywords.

See Also:

• Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
(package private) static final class	ExpressionRule.PostFixExpressionCompiler	Evaluate a boolean postfix expression.

Field Summary

Fields

Modifier and Type	Field	Description
private static final ExpressionRule.PostFixExpressionCompiler	COMPILER	Compiler.
private static final InFixToPostFix	CONVERTER	Converter.
private final Rule	rule	Rule.
(package private) static final long	serialVersionUID	Serialization ID.

Constructor Summary

Constructors

Modifier	Constructor	Description
private	ExpressionRule(Rule r)	Create new instance.

Method Summary

Modifier and Type	Method	Description
boolean	evaluate(org.apache.log4j.spi.LoggingEvent event, Map matches)	Returns true if this implementation of the rule accepts the LoggingEvent, or false if not.
static Rule	getRule(String expression)	Get rule.
static Rule	getRule(String expression, boolean isPostFix)	Get rule.
String	toString()

Methods inherited from class AbstractRule

addPropertyChangeListener, firePropertyChange, firePropertyChange, removePropertyChangeListener

Methods inherited from class Object

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

Field Details

serialVersionUID

static final long serialVersionUID

Serialization ID.

See Also:

• Constant Field Values

CONVERTER

private static final InFixToPostFix CONVERTER

Converter.

COMPILER

private static final ExpressionRule.PostFixExpressionCompiler COMPILER

Compiler.

rule

private final Rule rule

Rule.

Constructor Details

ExpressionRule

private ExpressionRule(Rule r)

Create new instance.

Parameters:

r - rule

Method Details

getRule

public static Rule getRule(String expression)

Get rule.

Parameters:

expression - expression.

Returns:

rule.

getRule

public static Rule getRule(String expression,
 boolean isPostFix)

Get rule.

Parameters:

expression - expression.

isPostFix - If post-fix.

Returns:

rule

evaluate

public boolean evaluate(org.apache.log4j.spi.LoggingEvent event,
 Map matches)

Returns true if this implementation of the rule accepts the LoggingEvent, or false if not.

What True/False means can be client-specific.

Parameters:

event - LoggingEvent this instance will evaluate

matches - a Map of event field keys to Sets of matching strings (may be null) which will be updated during execution of this method to include field and string matches based on the rule evaluation results

Returns:

true if this Rule instance accepts the event, otherwise false.

toString

public String toString()

Overrides:

toString in class Object