org.apache.taglibs.standard.util

Class ExpressionUtil

java.lang.Object

org.apache.taglibs.standard.util.ExpressionUtil

public class ExpressionUtil
extends Object

Helper functions for working with EL expressions.

Constructor Summary

Constructors

Constructor and Description
ExpressionUtil()

Method Summary

Modifier and Type	Method and Description
static ValueExpression	createValueExpression(PageContext pageContext, String expression, Class<?> expectedType) Create a value expression.
static <T> T	evaluate(ValueExpression expression, PageContext pageContext) Evaluate a value expression.
static boolean	evaluate(ValueExpression expression, PageContext pageContext, boolean fallback)
static int	evaluate(ValueExpression expression, PageContext pageContext, int fallback)
static ExpressionFactory	getExpressionFactory(PageContext pageContext) Return the JSP's ExpressionFactory.

Methods inherited from class java.lang.Object

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

Constructor Detail

ExpressionUtil

public ExpressionUtil()

Method Detail

createValueExpression

public static ValueExpression createValueExpression(PageContext pageContext,
                                                    String expression,
                                                    Class<?> expectedType)

Create a value expression.

Parameters:

pageContext - the context in which the expression will be parsed

expression - the expression

expectedType - the expected type of result

Returns:

a parsed expression

getExpressionFactory

public static ExpressionFactory getExpressionFactory(PageContext pageContext)

Return the JSP's ExpressionFactory.

Parameters:

pageContext - the context for the JSP

Returns:

the ExpressionFactory to use for EL expressions in that JSP

evaluate

public static <T> T evaluate(ValueExpression expression,
                             PageContext pageContext)

Evaluate a value expression. To support optional attributes, if the expression is null then null will be returned.

Type Parameters:

T - the expected type of the expression

Parameters:

expression - the expression

pageContext - the context for the JSP

Returns:

the result of evaluating the expression

evaluate

public static boolean evaluate(ValueExpression expression,
                               PageContext pageContext,
                               boolean fallback)

evaluate

public static int evaluate(ValueExpression expression,
                           PageContext pageContext,
                           int fallback)