Java XPath Expression valueOf(Node node, String xpath, NamespaceContext context)

Description

Evaluates an XPath expression given a namespace context and returns the String value of the result, similar to the value-of function in XSLT.

License

Open Source License

Parameter

Parameter	Description
node	the Node to evaluate the expression on
xpath	the XPath expression to evaluate

Return

a , or null if there is an error in the XPath expression.

Declaration

public static String valueOf(Node node, String xpath, NamespaceContext context)

Method Source Code


//package com.java2s;
/*/* w  w w.jav a  2 s . co  m*/
 * org.daisy.util (C) 2005-2008 Daisy Consortium
 * 
 * This library is free software; you can redistribute it and/or modify it under
 * the terms of the GNU Lesser General Public License as published by the Free
 * Software Foundation; either version 2.1 of the License, or (at your option)
 * any later version.
 * 
 * This library is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
 * details.
 * 
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library; if not, write to the Free Software Foundation, Inc.,
 * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */

import javax.xml.namespace.NamespaceContext;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;
import org.w3c.dom.Node;

public class Main {
    private static XPath xpathObj = XPathFactory.newInstance().newXPath();

    /**
     * Evaluates an XPath expression and returns the {@link String} value
     * of the result, similar to the <code>value-of</code> function in XSLT.
     * If there is an error in the XPath syntax, an empty string will be
     * returned.
     * @param node the {@link Node} to evaluate the expression on
     * @param xpath the XPath expression to evaluate
     * @return a {@link String}.
     */
    public static String valueOf(Node node, String xpath) {
        try {
            return (String) xpathObj.evaluate(xpath, node, XPathConstants.STRING);
        } catch (XPathExpressionException e) {
            return "";
        }
    }

    /**
     * Evaluates an XPath expression given a namespace context and returns
     * the {@link String} value of the result, similar to the
     * <code>value-of</code> function in XSLT. If there is an error in the
     * XPath syntax, an empty string will be returned. 
     * @param node the {@link Node} to evaluate the expression on
     * @param xpath the XPath expression to evaluate
     * @return a {@link NodeList}, or <code>null</code> if there is an
     * error in the XPath expression.
     */
    public static String valueOf(Node node, String xpath, NamespaceContext context) {
        try {
            xpathObj.setNamespaceContext(context);
            String result = (String) xpathObj.evaluate(xpath, node, XPathConstants.STRING);
            xpathObj.reset();
            return result;
        } catch (XPathExpressionException e) {
            return "";
        }
    }
}