Package org.apache.activemq.filter

Source Code of org.apache.activemq.filter.XalanXPathEvaluator

/**
* 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 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;

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();
            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);

            // We should associated the cachedXPathAPI object with the message
            // being evaluated
            // since that should speedup subsequent xpath expressions.
            CachedXPathAPI cachedXPathAPI = new CachedXPathAPI();
            NodeIterator iterator = cachedXPathAPI.selectNodeIterator(doc, xpath);
            return iterator.nextNode() != null;
        } catch (Throwable e) {
            return false;
        }
    }
}
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