org.displaytag.tags.el
Class ExpressionEvaluator

java.lang.Object
  org.displaytag.tags.el.ExpressionEvaluator

public class ExpressionEvaluator

extends java.lang.Object

Utility class to help with the evaluation of JSTL Expression Language. It mainly encapsulates the calls to ExpressionEvaluationManager to ease the use of this class.

Version:

$Revision: 1.6 $ ($Author: fgiust $)

Author:

Tim McCune, Fabrizio Giustina

Constructor Summary

ExpressionEvaluator(javax.servlet.jsp.tagext.Tag sourceTag, javax.servlet.jsp.PageContext context)
Creates a new ExpressionEvaluator for the given tag and pagecontext.

Method Summary

java.lang.Object	eval(java.lang.String attrName, java.lang.String attrValue, java.lang.Class returnClass) Evaluate expression in attrValue.
boolean	evalBoolean(java.lang.String attrName, java.lang.String attrValue) Evaluate expression in attrValueas as a boolean.
int	evalInt(java.lang.String attrName, java.lang.String attrValue) Evaluate expression in attrValueas as a int.
long	evalLong(java.lang.String attrName, java.lang.String attrValue) Evaluate expression in attrValueas as a long.
java.lang.String	evalString(java.lang.String attrName, java.lang.String attrValue) Evaluate expression in attrValueas as a String.

Methods inherited from class java.lang.Object

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

Constructor Detail

ExpressionEvaluator

public ExpressionEvaluator(javax.servlet.jsp.tagext.Tag sourceTag,
                           javax.servlet.jsp.PageContext context)

Creates a new ExpressionEvaluator for the given tag and pagecontext.

Parameters:

sourceTag - tag where the expression has to be evaluated

context - the page context

Method Detail

eval

public java.lang.Object eval(java.lang.String attrName,
                             java.lang.String attrValue,
                             java.lang.Class returnClass)
                      throws javax.servlet.jsp.JspException

Evaluate expression in attrValue.

Parameters:

attrName - attribute name

attrValue - attribute value

returnClass - class the returned object is instance of

Returns:

evaluate expression of attrValue, null if attrValue is null.

Throws:

javax.servlet.jsp.JspException - exception thrown by ExpressionEvaluatorManager

evalString

public java.lang.String evalString(java.lang.String attrName,
                                   java.lang.String attrValue)
                            throws javax.servlet.jsp.JspException

Evaluate expression in attrValueas as a String.

Parameters:

attrName - attribute name

attrValue - attribute value

Returns:

evaluate expression of attrValue, null if attrValue is null.

Throws:

javax.servlet.jsp.JspException - exception thrown by ExpressionEvaluatorManager

evalBoolean

public boolean evalBoolean(java.lang.String attrName,
                           java.lang.String attrValue)
                    throws javax.servlet.jsp.JspException

Evaluate expression in attrValueas as a boolean.

Parameters:

attrName - attribute name

attrValue - attribute value

Returns:

evaluate expression of attrValue, false if attrValue is null.

Throws:

javax.servlet.jsp.JspException - exception thrown by ExpressionEvaluatorManager

evalLong

public long evalLong(java.lang.String attrName,
                     java.lang.String attrValue)
              throws javax.servlet.jsp.JspException

Evaluate expression in attrValueas as a long.

Parameters:

attrName - attribute name

attrValue - attribute value

Returns:

evaluate expression of attrValue, -1 if attrValue is null.

Throws:

javax.servlet.jsp.JspException - exception thrown by ExpressionEvaluatorManager

evalInt

public int evalInt(java.lang.String attrName,
                   java.lang.String attrValue)
            throws javax.servlet.jsp.JspException

Evaluate expression in attrValueas as a int.

Parameters:

attrName - attribute name

attrValue - attribute value

Returns:

evaluate expression of attrValue, -1 if attrValue is null.

Throws:

javax.servlet.jsp.JspException - exception thrown by ExpressionEvaluatorManager