org.kuali.rice.krad.uif.service.impl
Class ExpressionEvaluatorServiceImpl

java.lang.Object
  org.kuali.rice.krad.uif.service.impl.ExpressionEvaluatorServiceImpl

All Implemented Interfaces:

ExpressionEvaluatorService

public class ExpressionEvaluatorServiceImpl
extends Object
implements ExpressionEvaluatorService

Evaluates expression language statements using the Spring EL engine TODO: Look into using Rice KRMS for evaluation

Author:

Kuali Rice Team (rice.collab@kuali.org)

Constructor Summary

ExpressionEvaluatorServiceImpl()

Method Summary

protected void	addCustomFunctions(org.springframework.expression.spel.support.StandardEvaluationContext context) Registers custom functions for el expressions with the given context
boolean	containsElPlaceholder(String value) Indicates whether or not the given string contains the el placholder (begin and end delimiters)
Object	evaluateExpression(Object contextObject, Map<String,Object> evaluationParameters, String expressionStr) Evaluates the given el expression against the content object and parameters, and returns the result of the evaluation
String	evaluateExpressionTemplate(Object contextObject, Map<String,Object> evaluationParameters, String expressionTemplate) Evaluates the given expression template string against the context object and map of parameters
void	evaluateObjectExpressions(Object object, Object contextObject, Map<String,Object> evaluationParameters) Evaluates any el expressions that are found as a string property value for the object
protected void	evaluatePropertyExpressions(Object object, Object contextObject, Map<String,Object> evaluationParameters) Retrieves the Map from the given object that containing the property expressions that should be evaluated.
protected void	evaluatePropertyReplacers(Object object, Object contextObject, Map<String,Object> evaluationParameters) Iterates through any configured PropertyReplacer instances for the component and evaluates the given condition.

Methods inherited from class java.lang.Object

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

Constructor Detail

ExpressionEvaluatorServiceImpl

public ExpressionEvaluatorServiceImpl()

Method Detail

evaluateObjectExpressions

public void evaluateObjectExpressions(Object object,
                                      Object contextObject,
                                      Map<String,Object> evaluationParameters)

Description copied from interface: ExpressionEvaluatorService

Evaluates any el expressions that are found as a string property value for the object

Using reflection the properties for the object are retrieved and if of String type the corresponding value is retrieved. If the value is not empty and contains the el placeholder see ExpressionEvaluatorService.containsElPlaceholder(String) then the expression is evaluated using the given context object and parameters. The evaluated string is then set as the new property value, or in the case of a template (expression contained within a literal string), the expression part is replaced in the property value.

In addition to evaluating any property expressions, any configured PropertyReplacer for the object are also evaluated and if a match occurs those property replacements are made

Specified by:

evaluateObjectExpressions in interface ExpressionEvaluatorService

Parameters:

object - - object whose properties should be checked for expressions and evaluated

contextObject - - context object for the expression evaluations

evaluationParameters - - map of parameters that may appear in expressions, the map key gives the parameter name that may appear in the expression, and the map value is the object that expression should evaluate against when that name is found

See Also:

ExpressionEvaluatorService.evaluateObjectExpressions(java.lang.Object, java.lang.Object, java.util.Map)

evaluateExpressionTemplate

public String evaluateExpressionTemplate(Object contextObject,
                                         Map<String,Object> evaluationParameters,
                                         String expressionTemplate)

Description copied from interface: ExpressionEvaluatorService

Evaluates the given expression template string against the context object and map of parameters

If the template string contains one or more el placeholders (see ExpressionEvaluatorService.containsElPlaceholder(String)), the expression contained within the placeholder will be evaluated and the corresponding value will be substituted back into the property value where the placeholder occurred. If no placeholders are found, the string will be returned unchanged

Specified by:

evaluateExpressionTemplate in interface ExpressionEvaluatorService

Parameters:

contextObject - - context object for the expression evaluations

evaluationParameters - - map of parameters that may appear in expressions, the map key gives the parameter name that may appear in the expression, and the map value is the object that expression should evaluate against when that name is found

expressionTemplate - - string that should be evaluated for el expressions

Returns:

String formed by replacing any el expressions in the original expression template with their corresponding evaluation results

See Also:

ExpressionEvaluatorService.evaluateExpressionTemplate(java.lang.Object, java.util.Map, java.lang.String)

evaluateExpression

public Object evaluateExpression(Object contextObject,
                                 Map<String,Object> evaluationParameters,
                                 String expressionStr)

Description copied from interface: ExpressionEvaluatorService

Evaluates the given el expression against the content object and parameters, and returns the result of the evaluation

The given expression string is assumed to be one el expression and should not contain the el placeholders. The returned result depends on the evaluation and what type is returns, for instance a boolean will be return for a boolean expression, or a string for string expression

Specified by:

evaluateExpression in interface ExpressionEvaluatorService

Parameters:

contextObject - - context object for the expression evaluations

evaluationParameters - - map of parameters that may appear in expressions, the map key gives the parameter name that may appear in the expression, and the map value is the object that expression should evaluate against when that name is found

expressionStr - - el expression to evaluate

Returns:

Object result of the expression evaluation

See Also:

ExpressionEvaluatorService.evaluateExpression(java.lang.Object, java.util.Map, java.lang.String)

addCustomFunctions

protected void addCustomFunctions(org.springframework.expression.spel.support.StandardEvaluationContext context)

Registers custom functions for el expressions with the given context

Parameters:

context - - context instance to register functions to

evaluatePropertyReplacers

protected void evaluatePropertyReplacers(Object object,
                                         Object contextObject,
                                         Map<String,Object> evaluationParameters)

Iterates through any configured PropertyReplacer instances for the component and evaluates the given condition. If the condition is met, the replacement value is set on the corresponding property

Parameters:

object - - object instance with property replacers list, should be either a component or layout manager

contextObject - - context for el evaluation

evaluationParameters - - parameters for el evaluation

evaluatePropertyExpressions

protected void evaluatePropertyExpressions(Object object,
                                           Object contextObject,
                                           Map<String,Object> evaluationParameters)

Retrieves the Map from the given object that containing the property expressions that should be evaluated. Each expression is then evaluated and the result is used to set the property value

If the expression is an el template (part static text and part expression), only the expression part will be replaced with the result. More than one expressions may be contained within the template

Parameters:

object - - object instance to evaluate expressions for

contextObject - - object providing the default context for expressions

evaluationParameters - - map of additional parameters that may be used within the expressions

containsElPlaceholder

public boolean containsElPlaceholder(String value)

Description copied from interface: ExpressionEvaluatorService

Indicates whether or not the given string contains the el placholder (begin and end delimiters)

Specified by:

containsElPlaceholder in interface ExpressionEvaluatorService

Parameters:

value - - String to check for contained placeholders

Returns:

boolean true if the string contains one or more placeholders, false if it contains none

See Also:

ExpressionEvaluatorService.containsElPlaceholder(java.lang.String)