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• XMLExtractor.java

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gov.nasa.pds.tools.util.XMLExtractor Maven / Gradle / Ivy

// Copyright 2006-2014, by the California Institute of Technology.
// ALL RIGHTS RESERVED. United States Government Sponsorship acknowledged.
// Any commercial use must be negotiated with the Office of Technology Transfer
// at the California Institute of Technology.
//
// This software is subject to U. S. export control laws and regulations
// (22 C.F.R. 120-130 and 15 C.F.R. 730-774). To the extent that the software
// is subject to U.S. export control laws and regulations, the recipient has
// the responsibility to obtain export licenses or other export authority as
// may be required before exporting such information to foreign countries or
// providing access to foreign nationals.
//
// $Id$
package gov.nasa.pds.tools.util;

import java.io.File;
import java.io.IOException;
import java.net.MalformedURLException;
import java.net.URISyntaxException;
import java.net.URL;
import java.util.ArrayList;
import java.util.List;

import javax.xml.transform.Source;
import javax.xml.transform.sax.SAXSource;
import javax.xml.xpath.XPathConstants;
import javax.xml.xpath.XPathExpressionException;

import net.sf.saxon.Configuration;
import net.sf.saxon.lib.ParseOptions;
import net.sf.saxon.om.DocumentInfo;
import net.sf.saxon.om.TreeInfo;
import net.sf.saxon.tree.tiny.TinyNodeImpl;
import net.sf.saxon.trans.XPathException;
import net.sf.saxon.xpath.XPathEvaluator;



import org.xml.sax.InputSource;

/**
 * Class to extract data from an XML file.
*/
public class XMLExtractor {
    /** The DOM source. */
    private Source xml = null;

    /** The XPath evaluator object. */
    private XPathEvaluator xpath = null;

    public static final String SCHEMA_LOCATION_XPATH = "//*/@xsi:schemaLocation";

    public static final String XML_MODEL_XPATH = "/processing-instruction('xml-model')";

    public static final String DEFAULT_NAMESPACE = "//*/namespace::*[name()='']";

    public static final String TARGET_NAMESPACE = "//*/@targetNamespace";

    /**
     * Constructor.
     *
     * @param xml A parsed XML document.
     *
     * @throws XPathException If an error occurred while parsing the given
     *  xml file.
     * @throws XPathExpressionException If an error occurred while setting up
     * the default namespace.
     *
     */
    public XMLExtractor(Source xml) throws XPathExpressionException,
    XPathException {
      this.xml = xml;
      this.xpath = new XPathEvaluator();
        Configuration configuration = xpath.getConfiguration();

      configuration.setLineNumbering(true);
      configuration.setXIncludeAware(Utility.supportXincludes());
      String definedNamespace = getValueFromDoc("namespace-uri(/*)");
      xpath.getStaticContext().setDefaultElementNamespace(definedNamespace);
    }
    
    /**
     * Constructor.
     *
     * @param xmlFile An xml file.
     *
     * @throws XPathException If an error occurred while parsing the given
     *  xml file.
     * @throws XPathExpressionException If an error occurred while setting up
     * the default namespace.
     */
    public XMLExtractor(URL url) throws XPathException,
    XPathExpressionException {
      xpath = new XPathEvaluator();
      Configuration configuration = xpath.getConfiguration();
      configuration.setLineNumbering(true);
      configuration.setXIncludeAware(Utility.supportXincludes());
      ParseOptions options = new ParseOptions();
      options.setErrorListener(new XMLErrorListener());
      try {
        xml = configuration.buildDocument(new SAXSource(Utility.openConnection(url)),
            options);
        String definedNamespace = getValueFromDoc("namespace-uri(/*)");
        xpath.getStaticContext().setDefaultElementNamespace(definedNamespace);
      } catch (IOException io) {
        throw new XPathException("Error while reading input: " + io.getMessage());
      }
    }

    public XMLExtractor(InputSource source) throws XPathException,
    XPathExpressionException {
      xpath = new XPathEvaluator();
      Configuration configuration = xpath.getConfiguration();
      configuration.setLineNumbering(true);
      configuration.setXIncludeAware(Utility.supportXincludes());
      ParseOptions options = new ParseOptions();
      options.setErrorListener(new XMLErrorListener());
      xml = configuration.buildDocument(new SAXSource(source),
          options);
      String definedNamespace = getValueFromDoc("namespace-uri(/*)");
      xpath.getStaticContext().setDefaultElementNamespace(definedNamespace);
    }

    public XMLExtractor (File file) throws XPathException,
    XPathExpressionException, MalformedURLException {
      this(file.toURI().toURL());
    }

    /**
     * Constructor.
     *
     * @param xmlFile An xml file.
     *
     * @throws XPathException If an error occurred while parsing the given
     *  xml file.
     * @throws XPathExpressionException If an error occurred while setting up
     * the default namespace.
     * @throws MalformedURLException
     */
    public XMLExtractor (String url) throws XPathException,
    XPathExpressionException, MalformedURLException {
        this(new URL(url));
    }

    /**
     * Gets the value of the given expression.
     *
     * @param expression An XPath expression.
     *
     * @return The resulting value or null if nothing was found.
     *
     * @throws XPathExpressionException If the given expression was malformed.
     * @throws XPathException
     */
    public String getValueFromDoc(String expression)
    throws XPathExpressionException, XPathException {
        TreeInfo ti = xpath.getConfiguration().buildDocumentTree(xml);
        return getValueFromItem(expression, ti); //xpath.setSource(xml));
    }

    /**
     * Gets the value of the given expression.
     *
     * @param expression An XPath expression.
     * @param item The starting point from which to evaluate the
     * XPath expression.
     *
     * @return The resulting value or null if nothing was found.
     *
     * @throws XPathExpressionException If the given expression was malformed.
     */
    public String getValueFromItem(String expression, Object item)
    throws XPathExpressionException {
        return xpath.evaluate(expression, item);
    }

    /**
     * Gets a Node object from the given expression.
     *
     * @param expression An XPath expression.
     *
     * @return A Node object.
     *
     * @throws XPathExpressionException If the given expression was malformed.
     */
    public TinyNodeImpl getNodeFromDoc(String expression)
            throws XPathExpressionException, XPathException {
        return getNodeFromItem(expression, xpath.getConfiguration().buildDocumentTree(xml));
    }

    /**
     * Gets a Node object from the given expression.
     *
     * @param expression An XPath expression.
     * @param item The starting point from which to evaluate the
     * XPath expression.
     *
     * @return A Node object.
     *
     * @throws XPathExpressionException If the given expression was malformed.
     */
    public TinyNodeImpl getNodeFromItem(String expression, Object item)
    throws XPathExpressionException {
        return (TinyNodeImpl) xpath.evaluate(expression, item,
            XPathConstants.NODE);
    }

    /**
     * Gets the values of the given expression.
     *
     * @param expression An XPath expression.
     *
     * @return The resulting values or an empty list if nothing was found.
     *
     * @throws XPathExpressionException If the given expression was malformed.
     */
    public List getValuesFromDoc(String expression)
            throws XPathExpressionException, XPathException {
        return getValuesFromItem(expression, xpath.getConfiguration().buildDocumentTree(xml));
    }

    /**
     * Gets the values of the given expression.
     *
     * @param expression An XPath expression.
     * @param item The starting point from which to evaluate the
     * XPath expression.
     *
     * @return The resulting values or an empty list if nothing was found.
     *
     * @throws XPathExpressionException If the given expression was malformed.
     */
    public List getValuesFromItem(String expression, Object item)
    throws XPathExpressionException {
        List vals = new ArrayList();
        List nList = (List) xpath.evaluate(
            expression, item, XPathConstants.NODESET);
        if (nList != null) {
            for (int i = 0, sz = nList.size(); i < sz; i++) {
                TinyNodeImpl aNode = nList.get(i);
                vals.add(aNode.getStringValue());
            }
        }
        return vals;
    }

    /**
     * Gets the document node of the XML document.
     *
     * @return The Document Node.
     * @throws XPathException
     */
    public Source getDocNode() throws XPathException {
        return xml;
    }

    /**
     * Gets Node objects from the given expression.
     *
     * @param expression An XPath expression.
     *
     * @return A NodeList object.
     *
     * @throws XPathExpressionException If the given expression was malformed.
     */
    public List getNodesFromDoc(String expression)
            throws XPathExpressionException, XPathException {
        return getNodesFromItem(expression, xpath.getConfiguration().buildDocumentTree(xml));
    }

    /**
     * Gets Node objects from the given expression.
     *
     * @param expression An XPath expression.
     * @param item The starting point from which to evaluate the
     * XPath expression.
     *
     * @return A NodeList object.
     *
     * @throws XPathExpressionException If the given expression was malformed.
     */
    public List getNodesFromItem(String expression, Object item)
    throws XPathExpressionException {
        return (List) xpath.evaluate(
                expression, item, XPathConstants.NODESET);
    }

    /**
     *
     * @return Returns the schemalocation attribute value from the label.
     * If it was not found, a null value will be returned.
     *
     * @throws XPathExpressionException
     * @throws XPathException
     */
    public String getSchemaLocation() throws XPathExpressionException,
    XPathException {
      return getValueFromDoc(SCHEMA_LOCATION_XPATH);
    }

    /**
     * @return Returns the schematron specifications in the label.
     * @throws XPathExpressionException
     */
    public List getXmlModels() throws XPathExpressionException, XPathException {
      return getValuesFromDoc(XML_MODEL_XPATH);
    }

    /**
     *
     * @return Returns the 'xmlns' attribute of the document (default namespace)
     * @throws XPathExpressionException
     * @throws XPathException
     */
    public String getDefaultNamespace() throws XPathExpressionException, XPathException {
      return getValueFromDoc(DEFAULT_NAMESPACE);
    }

    /**
    *
    * @return Returns the 'targetNamespace' attribute of the document
    * (default namespace)
    * @throws XPathExpressionException
    * @throws XPathException
    */
    public String getTargetNamespace() throws XPathExpressionException, XPathException {
      return getValueFromDoc(TARGET_NAMESPACE);
    }
    
    public String getSystemId() {
      return this.xml.getSystemId();
    }
}