/*
* $Id: EvalHelper.java 471754 2006-11-06 14:55:09Z husted $
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.strutsel.taglib.utils;
import org.apache.taglibs.standard.lang.support.ExpressionEvaluatorManager;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.Tag;
/**
* This class is used in the <code>evaluateExpressions</code> method of each
* Tag class. It is used to process the original attribute value through the
* JSTL EL engine to produce an evaluated value. It provides functions to
* evaluate the expression assuming it is an Object, String, Integer, or
* Boolean result.
*/
public final class EvalHelper {
private EvalHelper() {
}
/**
* Evaluates the attribute value in the JSTL EL engine, returning the raw
* Object value of the evaluated expression. If the original expression
* is null, or the resulting value is null, it will return null.
*/
public static Object eval(String attrName, String attrValue, Tag tagObject,
PageContext pageContext)
throws JspException {
Object result = null;
if (attrValue != null) {
result =
ExpressionEvaluatorManager.evaluate(attrName, attrValue,
Object.class, tagObject, pageContext);
}
return (result);
}
/**
* Evaluates the attribute value in the JSTL EL engine, assuming the
* resulting value is a String object. If the original expression is
* null, or the resulting value is null, it will return null.
*/
public static String evalString(String attrName, String attrValue,
Tag tagObject, PageContext pageContext)
throws JspException {
Object result = null;
if (attrValue != null) {
result =
ExpressionEvaluatorManager.evaluate(attrName, attrValue,
String.class, tagObject, pageContext);
}
return ((String) result);
}
/**
* Evaluates the attribute value in the JSTL EL engine, assuming the
* resulting value is an Integer object. If the original expression is
* null, or the resulting value is null, it will return null.
*/
public static Integer evalInteger(String attrName, String attrValue,
Tag tagObject, PageContext pageContext)
throws JspException {
Object result = null;
if (attrValue != null) {
result =
ExpressionEvaluatorManager.evaluate(attrName, attrValue,
Integer.class, tagObject, pageContext);
}
return ((Integer) result);
}
/**
* Evaluates the attribute value in the JSTL EL engine, assuming the
* resulting value is an Boolean object. If the original expression is
* null, or the resulting value is null, it will return null.
*/
public static Boolean evalBoolean(String attrName, String attrValue,
Tag tagObject, PageContext pageContext)
throws JspException {
Object result = null;
if (attrValue != null) {
result =
ExpressionEvaluatorManager.evaluate(attrName, attrValue,
Boolean.class, tagObject, pageContext);
}
return ((Boolean) result);
}
}