com.jkoolcloud.tnt4j.streams.transform.XPathTransformation.java Source code

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Here is the source code for com.jkoolcloud.tnt4j.streams.transform.XPathTransformation.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.transform;

import java.util.HashMap;
import java.util.Map;

import javax.xml.namespace.QName;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathVariableResolver;

import org.apache.commons.collections4.CollectionUtils;

import com.jkoolcloud.tnt4j.core.Property;
import com.jkoolcloud.tnt4j.sink.DefaultEventSinkFactory;
import com.jkoolcloud.tnt4j.sink.EventSink;
import com.jkoolcloud.tnt4j.streams.fields.ActivityInfo;
import com.jkoolcloud.tnt4j.streams.utils.StreamsResources;
import com.jkoolcloud.tnt4j.streams.utils.StreamsScriptingUtils;
import com.jkoolcloud.tnt4j.streams.utils.StreamsXMLUtils;

/**
 * Data value transformation based on XPath function expressions.
 *
 * @version $Revision: 1 $
 *
 * @see com.jkoolcloud.tnt4j.streams.utils.StreamsXMLUtils#getStreamsXPath()
 * @see XPathVariableResolver
 * @see javax.xml.xpath.XPathFunctionResolver
 * @see javax.xml.namespace.NamespaceContext
 * @see javax.xml.xpath.XPathFunction
 * @see XPath#evaluate(String, Object)
 */
public class XPathTransformation extends AbstractScriptTransformation<Object> {
    private static final EventSink LOGGER = DefaultEventSinkFactory.defaultEventSink(XPathTransformation.class);

    private static final String OWN_FIELD_VALUE_KEY = "<!TNT4J_XPATH_TRSF_FLD_VALUE!>"; // NON-NLS;

    /**
     * Constructs a new XPathTransformation.
     *
     * @param name
     *            transformation name
     * @param scriptCode
     *            XPath expression code
     */
    public XPathTransformation(String name, String scriptCode) {
        super(name, scriptCode);
    }

    /**
     * Constructs a new XPathTransformation.
     *
     * @param name
     *            transformation name
     * @param scriptCode
     *            XPath expression code
     * @param phase
     *            activity data value resolution phase
     */
    public XPathTransformation(String name, String scriptCode, Phase phase) {
        super(name, scriptCode, phase);
    }

    @Override
    protected EventSink getLogger() {
        return LOGGER;
    }

    @Override
    protected String getHandledLanguage() {
        return StreamsScriptingUtils.XPATH_SCRIPT_LANG;
    }

    @Override
    public Object transform(Object value, ActivityInfo ai) throws TransformationException {
        Map<String, Object> valuesMap = new HashMap<>();
        valuesMap.put(OWN_FIELD_VALUE_KEY, value);

        if (ai != null && CollectionUtils.isNotEmpty(exprVars)) {
            for (String eVar : exprVars) {
                Property eKV = resolveFieldKeyAndValue(eVar, ai);

                valuesMap.put(eKV.getKey(), eKV.getValue());
            }
        }

        XPath xPath = StreamsXMLUtils.getStreamsXPath();
        xPath.setXPathVariableResolver(new StreamsVariableResolver(valuesMap));

        try {
            Object tValue = xPath.evaluate(getExpression(), (Object) null);

            logEvaluationResult(valuesMap, tValue);

            return tValue;
        } catch (Exception exc) {
            throw new TransformationException(
                    StreamsResources.getStringFormatted(StreamsResources.RESOURCE_BUNDLE_NAME,
                            "ValueTransformation.transformation.failed", getName(), getPhase()),
                    exc);
        }
    }

    private static class StreamsVariableResolver implements XPathVariableResolver {
        private Map<String, Object> valuesMap;

        private StreamsVariableResolver(Map<String, Object> valuesMap) {
            this.valuesMap = valuesMap;
        }

        @Override
        public Object resolveVariable(QName variableName) {
            Object varValue;
            if (variableName.equals(new QName(StreamsScriptingUtils.FIELD_VALUE_VARIABLE_NAME))) {
                varValue = valuesMap.get(OWN_FIELD_VALUE_KEY);
            } else {
                String varNameStr = "$" + variableName.toString(); // NON-NLS

                varValue = valuesMap.get(varNameStr);
            }

            return varValue == null ? "" : varValue;
        }
    }
}