org.mule.expression
Class DefaultExpressionManager

java.lang.Object
  org.mule.expression.DefaultExpressionManager

All Implemented Interfaces:

ExpressionManager

public class DefaultExpressionManager
extends Object
implements ExpressionManager

Provides universal access for evaluating expressions embedded in Mule configurations, such as Xml, Java, scripting and annotations.

Users can register or unregister ExpressionEvaluator through this interface.

Field Summary

protected static Log

logger logger used by this class

Fields inherited from interface org.mule.api.expression.ExpressionManager

DEFAULT_EXPRESSION_POSTFIX, DEFAULT_EXPRESSION_PREFIX

Constructor Summary

DefaultExpressionManager()

Method Summary

void	clearEvaluators() Clears all registered evaluators from the manager.
Object	evaluate(String expression, MuleMessage message) Evaluates the given expression.
Object	evaluate(String expression, MuleMessage message, boolean failIfNull) Evaluates the given expression.
Object	evaluate(String expression, String evaluator, MuleMessage message, boolean failIfNull) Evaluates the given expression.
boolean	isEvaluatorRegistered(String name) Checks whether an evaluator is registered with the manager
boolean	isValidExpression(String expression) Determines if the expression is valid or not.
String	parse(String expression, MuleMessage message) Evaluates expressions in a given string.
String	parse(String expression, MuleMessage message, boolean failIfNull) Evaluates expressions in a given string.
void	registerEvaluator(ExpressionEvaluator evaluator)
ExpressionEvaluator	unregisterEvaluator(String name) Removes the evaluator with the given name

Methods inherited from class java.lang.Object

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

Field Detail

logger

protected static final transient Log logger

logger used by this class

Constructor Detail

DefaultExpressionManager

public DefaultExpressionManager()

Method Detail

registerEvaluator

public void registerEvaluator(ExpressionEvaluator evaluator)

Specified by:

registerEvaluator in interface ExpressionManager

isEvaluatorRegistered

public boolean isEvaluatorRegistered(String name)

Checks whether an evaluator is registered with the manager

Specified by:

isEvaluatorRegistered in interface ExpressionManager

Parameters:

name - the name of the expression evaluator

Returns:

true if the evaluator is registered with the manager, false otherwise

unregisterEvaluator

public ExpressionEvaluator unregisterEvaluator(String name)

Removes the evaluator with the given name

Specified by:

unregisterEvaluator in interface ExpressionManager

Parameters:

name - the name of the evaluator to remove

Returns:

the evaluator that was removed. This will be null if the evaluator was not registered

evaluate

public Object evaluate(String expression,
                       MuleMessage message)
                throws ExpressionRuntimeException

Evaluates the given expression. The expression should be a single expression definition with or without enclosing braces. i.e. "mule:serviceName" and "#[mule:serviceName]" are both valid. For situations where one or more expressions need to be parsed within a single text, the ExpressionManager.parse(String,org.mule.api.MuleMessage,boolean) method should be used since it will iterate through all expressions in a string.

Specified by:

evaluate in interface ExpressionManager

Parameters:

expression - a single expression i.e. xpath://foo

message - the current message to process. The expression will evaluata on the message.

Returns:

the result of the evaluation. Expressions that return collection will return an empty collection, not null.

Throws:

ExpressionRuntimeException - if the expression is invalid, or a null is found for the expression and 'failIfNull is set to true.

evaluate

public Object evaluate(String expression,
                       MuleMessage message,
                       boolean failIfNull)
                throws ExpressionRuntimeException

Evaluates the given expression. The expression should be a single expression definition with or without enclosing braces. i.e. "mule:serviceName" and "#[mule:serviceName]" are both valid. For situations where one or more expressions need to be parsed within a single text, the ExpressionManager.parse(String,org.mule.api.MuleMessage,boolean) method should be used since it will iterate through all expressions in a string.

Specified by:

evaluate in interface ExpressionManager

Parameters:

expression - a single expression i.e. xpath://foo

message - the current message to process. The expression will evaluata on the message.

failIfNull - determines if an exception should be thrown if expression could not be evaluated or returns null.

Returns:

the result of the evaluation. Expressions that return collection will return an empty collection, not null.

Throws:

ExpressionRuntimeException - if the expression is invalid, or a null is found for the expression and 'failIfNull is set to true.

evaluate

public Object evaluate(String expression,
                       String evaluator,
                       MuleMessage message,
                       boolean failIfNull)
                throws ExpressionRuntimeException

Evaluates the given expression. The expression should be a single expression definition with or without enclosing braces. i.e. "mule:serviceName" and "#[mule:serviceName]" are both valid. For situations where one or more expressions need to be parsed within a single text, the ExpressionManager.parse(String,org.mule.api.MuleMessage,boolean) method should be used since it will iterate through all expressions in a string.

Specified by:

evaluate in interface ExpressionManager

Parameters:

expression - a single expression i.e. xpath://foo

evaluator - the evaluator to use when executing the expression

message - the current message to process. The expression will evaluata on the message.

failIfNull - determines if an exception should be thrown if expression could not be evaluated or returns null or if an exception should be thrown if an empty collection is returned.

Returns:

the result of the evaluation. Expressions that return collection will return an empty collection, not null.

Throws:

ExpressionRuntimeException - if the expression is invalid, or a null is found for the expression and 'failIfNull is set to true.

parse

public String parse(String expression,
                    MuleMessage message)
             throws ExpressionRuntimeException

Evaluates expressions in a given string. This method will iterate through each expression and evaluate it. If a user needs to evaluate a single expression they can use ExpressionManager.evaluate(String,org.mule.api.MuleMessage,boolean).

Specified by:

parse in interface ExpressionManager

Parameters:

expression - a single expression i.e. xpath://foo

message - the current message to process. The expression will evaluata on the message.

Returns:

the result of the evaluation. Expressions that return collection will return an empty collection, not null.

Throws:

ExpressionRuntimeException - if the expression is invalid, or a null is found for the expression and 'failIfNull is set to true.

parse

public String parse(String expression,
                    MuleMessage message,
                    boolean failIfNull)
             throws ExpressionRuntimeException

Evaluates expressions in a given string. This method will iterate through each expression and evaluate it. If a user needs to evaluate a single expression they can use ExpressionManager.evaluate(String,org.mule.api.MuleMessage,boolean).

Specified by:

parse in interface ExpressionManager

Parameters:

expression - a single expression i.e. xpath://foo

message - the current message to process. The expression will evaluata on the message.

failIfNull - determines if an exception should be thrown if expression could not be evaluated or returns null.

Returns:

the result of the evaluation. Expressions that return collection will return an empty collection, not null.

Throws:

ExpressionRuntimeException - if the expression is invalid, or a null is found for the expression and 'failIfNull is set to true.

clearEvaluators

public void clearEvaluators()

Clears all registered evaluators from the manager.

Specified by:

clearEvaluators in interface ExpressionManager

isValidExpression

public boolean isValidExpression(String expression)

Determines if the expression is valid or not. This method will validate a single expression or expressions embedded in a string. the expression must be well formed i.e. #[bean:user]

Specified by:

isValidExpression in interface ExpressionManager

Parameters:

expression - the expression to validate

Returns:

true if the expression evaluator is recognised