ActiveMQ example source code file (XalanXPathEvaluator.java)

This example ActiveMQ source code file (XalanXPathEvaluator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - ActiveMQ tags/keywords

bytesmessage, bytesmessage, cachedxpathapi, cachedxpathapi, document, documentbuilder, documentbuilderfactory, dom, inputsource, inputsource, io, nodeiterator, parser, sax, string, throwable, xalanxpathevaluator, xalanxpathevaluator, xml, xpath

The ActiveMQ XalanXPathEvaluator.java source code

/**
 * 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.activemq.filter;

import java.io.StringReader;

import javax.jms.BytesMessage;
import javax.jms.JMSException;
import javax.jms.TextMessage;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;

import org.w3c.dom.Document;
import org.w3c.dom.traversal.NodeIterator;
import org.xml.sax.InputSource;

import org.apache.activemq.command.Message;
import org.apache.activemq.util.ByteArrayInputStream;
import org.apache.xpath.CachedXPathAPI;
import org.apache.xpath.objects.XObject;


public class XalanXPathEvaluator implements XPathExpression.XPathEvaluator {

    private final String xpath;

    public XalanXPathEvaluator(String xpath) {
        this.xpath = xpath;
    }

    public boolean evaluate(Message m) throws JMSException {
        if (m instanceof TextMessage) {
            String text = ((TextMessage)m).getText();
            return evaluate(text);
        } else if (m instanceof BytesMessage) {
            BytesMessage bm = (BytesMessage)m;
            byte data[] = new byte[(int)bm.getBodyLength()];
            bm.readBytes(data);
            return evaluate(data);
        }
        return false;
    }

    private boolean evaluate(byte[] data) {
        try {

            InputSource inputSource = new InputSource(new ByteArrayInputStream(data));

            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            factory.setNamespaceAware(true);
            DocumentBuilder dbuilder = factory.newDocumentBuilder();
            Document doc = dbuilder.parse(inputSource);
            
            CachedXPathAPI cachedXPathAPI = new CachedXPathAPI();
            XObject result = cachedXPathAPI.eval(doc, xpath);
            if (result.bool())
            	return true;
            else {
            	NodeIterator iterator = cachedXPathAPI.selectNodeIterator(doc, xpath);
            	return (iterator.nextNode() != null);
            }  

        } catch (Throwable e) {
            return false;
        }
    }

    private boolean evaluate(String text) {
        try {
            InputSource inputSource = new InputSource(new StringReader(text));

            DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
            factory.setNamespaceAware(true);
            DocumentBuilder dbuilder = factory.newDocumentBuilder();
            Document doc = dbuilder.parse(inputSource);

            //An XPath expression could return a true or false value instead of a node.
            //eval() is a better way to determine the boolean value of the exp.
            //For compliance with legacy behavior where selecting an empty node returns true,
            //selectNodeIterator is attempted in case of a failure.
            
            CachedXPathAPI cachedXPathAPI = new CachedXPathAPI();
            XObject result = cachedXPathAPI.eval(doc, xpath);
            if (result.bool())
            	return true;
            else {
            	NodeIterator iterator = cachedXPathAPI.selectNodeIterator(doc, xpath);
            	return (iterator.nextNode() != null);
            }    	
            
        } catch (Throwable e) {
            return false;
        }
    }
}