com.jkoolcloud.tnt4j.streams.matchers.XPathMatcher.java Source code

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Here is the source code for com.jkoolcloud.tnt4j.streams.matchers.XPathMatcher.java

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/*
 * Copyright 2014-2018 JKOOL, LLC.
 *
 * Licensed 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 com.jkoolcloud.tnt4j.streams.matchers;

import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.xpath.XPath;

import org.apache.commons.io.IOUtils;
import org.apache.commons.lang3.StringUtils;
import org.w3c.dom.Node;

import com.jkoolcloud.tnt4j.streams.utils.StreamsXMLUtils;
import com.jkoolcloud.tnt4j.streams.utils.Utils;

/**
 * Data string or {@link org.w3c.dom.Node} value match expression evaluation based on {@link javax.xml.xpath.XPath}
 * expressions.
 *
 * @version $Revision: 1 $
 */
public class XPathMatcher implements Matcher {

    private XPath xPath;
    private DocumentBuilder builder;

    private final Lock xPathLock = new ReentrantLock();
    private final Lock builderLock = new ReentrantLock();

    private static XPathMatcher instance;

    private XPathMatcher() throws Exception {
        DocumentBuilderFactory domFactory = DocumentBuilderFactory.newInstance();
        domFactory.setNamespaceAware(false);
        builder = domFactory.newDocumentBuilder();
        xPath = StreamsXMLUtils.getStreamsXPath();
    }

    static synchronized XPathMatcher getInstance() throws Exception {
        if (instance == null) {
            instance = new XPathMatcher();
        }

        return instance;
    }

    @Override
    public boolean isDataClassSupported(Object data) {
        return String.class.isInstance(data) || Node.class.isInstance(data);
    }

    /**
     * Evaluates match <tt>expression</tt> against provided <tt>data</tt> using XPath.
     *
     * @param expression
     *            XPath expression to check
     * @param data
     *            data {@link String} or {@link org.w3c.dom.Node} to evaluate expression to
     * @return true if expression returns any result
     */
    @Override
    public boolean evaluate(String expression, Object data) throws Exception {
        Node xmlDoc;
        if (data instanceof Node) {
            xmlDoc = (Node) data;
        } else {
            String xmlString = Utils.toString(data);
            if (StringUtils.isEmpty(xmlString)) {
                return false;
            }
            builderLock.lock();
            try {
                xmlDoc = builder.parse(IOUtils.toInputStream(xmlString, Utils.UTF8));
            } finally {
                builderLock.unlock();
            }
        }
        xPathLock.lock();
        try {
            String expressionResult = xPath.evaluate(expression, xmlDoc);

            if ("true".equalsIgnoreCase(expressionResult) || "false".equalsIgnoreCase(expressionResult)) { // NON-NLS
                return Boolean.parseBoolean(expressionResult);
            }

            return StringUtils.isNotEmpty(expressionResult);
        } finally {
            xPathLock.unlock();
        }
    }
}