org.apache.taglibs.standard.tag.el.core.ExpressionUtil Maven / Gradle / Ivy
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/*
* The contents of this file are subject to the terms
* of the Common Development and Distribution License
* (the "License"). You may not use this file except
* in compliance with the License.
*
* You can obtain a copy of the license at
* glassfish/bootstrap/legal/CDDLv1.0.txt or
* https://glassfish.dev.java.net/public/CDDLv1.0.html.
* See the License for the specific language governing
* permissions and limitations under the License.
*
* When distributing Covered Code, include this CDDL
* HEADER in each file and include the License file at
* glassfish/bootstrap/legal/CDDLv1.0.txt. If applicable,
* add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your
* own identifying information: Portions Copyright [yyyy]
* [name of copyright owner]
*
* Copyright 2005 Sun Microsystems, Inc. All rights reserved.
*
* Portions Copyright Apache Software Foundation.
*/
package org.apache.taglibs.standard.tag.el.core;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.Tag;
import org.apache.taglibs.standard.lang.support.ExpressionEvaluatorManager;
import org.apache.taglibs.standard.tag.common.core.NullAttributeException;
/**
* Contains some static utilities to facilitate common forms of
* expression evaluation.
*
* @author Shawn Bayern
*/
public class ExpressionUtil {
/** Evaluates an expression if present, but does not allow the expression
* to evaluate to 'null', throwing a NullAttributeException if it
* does. The function can return null, however, if the
* expression itself is null.
*/
public static Object evalNotNull(String tagName,
String attributeName,
String expression,
Class expectedType,
Tag tag,
PageContext pageContext)
throws JspException {
if (expression != null) {
Object r = ExpressionEvaluatorManager.evaluate(
attributeName, expression, expectedType, tag, pageContext);
if (r == null)
throw new NullAttributeException(tagName, attributeName);
return r;
} else
return null;
}
}