XPathBolt.java

package main.java.bolts;

import static main.java.utils.constants.WorkberchConstants.INDEX_FIELD;

import java.io.IOException;
import java.io.StringReader;
import java.util.ArrayList;
import java.util.List;

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;
import javax.xml.xpath.XPath;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpression;
import javax.xml.xpath.XPathExpressionException;
import javax.xml.xpath.XPathFactory;

import main.java.utils.WorkberchTuple;

import org.w3c.dom.Document;
import org.w3c.dom.NodeList;
import org.xml.sax.InputSource;
import org.xml.sax.SAXException;

import backtype.storm.topology.BasicOutputCollector;

import com.fasterxml.jackson.databind.JsonNode;

public class XPathBolt extends WorkberchTavernaProcessorBolt {

	private static final long serialVersionUID = 1L;

	String xPathExpression;

	public XPathBolt(final String guid, final List<String> outputFields, final String xPathExpression) {
		super(guid, outputFields);
		this.xPathExpression = xPathExpression;
	}

	public XPathBolt(final String guid, final List<String> inputFields, final List<String> outputFields, final JsonNode node) {
		super(guid, inputFields, outputFields, node);
	}

	@Override
	public void executeLogic(final WorkberchTuple tuple, final BasicOutputCollector collector, final boolean lastValue, final String uuid) {
		try {

			final XPathFactory xPathfactory = XPathFactory.newInstance();
			final XPath xpath = xPathfactory.newXPath();
			final XPathExpression expr = xpath.compile(xPathExpression);

			final DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
			DocumentBuilder builder;

			final Object value = tuple.getValues().values().toArray()[1];
			
			final String xmlString = value.toString();

			builder = factory.newDocumentBuilder();
			final Document document = builder.parse(new InputSource(new StringReader(xmlString)));
			final NodeList nl = (NodeList) expr.evaluate(document, XPathConstants.NODESET);

			final List<Object> emitTuple = new ArrayList<Object>();

			for (int i = 0; i < nl.getLength(); i++) {
				final String nodeContent = nl.item(i).getTextContent();
				emitTuple.add(nodeContent);

			}
			final List<Object> salida = new ArrayList<Object>();
			salida.add(emitTuple);
			salida.add(tuple.getValues().get(INDEX_FIELD));
			emitTuple(salida, collector, lastValue, uuid);

		} catch (final XPathExpressionException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (final ParserConfigurationException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (final SAXException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		} catch (final IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}

	}

	@Override
	protected void initFromJsonNode(final JsonNode jsonNode) {
		xPathExpression = jsonNode.get("xpathExpression").asText();
	}

}