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    1   /* XmlUtils
    2    *
    3    * Created on Sep 19, 2007
    4    *
    5    * Copyright (C) 2007 Internet Archive.
    6    *
    7    * This file is part of the Heritrix web crawler (crawler.archive.org).
    8    *
    9    * Heritrix is free software; you can redistribute it and/or modify
    10   * it under the terms of the GNU Lesser Public License as published by
    11   * the Free Software Foundation; either version 2.1 of the License, or
    12   * any later version.
    13   *
    14   * Heritrix is distributed in the hope that it will be useful,
    15   * but WITHOUT ANY WARRANTY; without even the implied warranty of
    16   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    17   * GNU Lesser Public License for more details.
    18   *
    19   * You should have received a copy of the GNU Lesser Public License
    20   * along with Heritrix; if not, write to the Free Software
    21   * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
    22   */
    23  package org.archive.util;
    24
    25  import java.io.File;
    26  import java.io.IOException;
    27  import java.util.logging.Logger;
    28
    29  import javax.xml.parsers.DocumentBuilder;
    30  import javax.xml.parsers.DocumentBuilderFactory;
    31  import javax.xml.parsers.ParserConfigurationException;
    32  import javax.xml.xpath.XPath;
    33  import javax.xml.xpath.XPathExpression;
    34  import javax.xml.xpath.XPathExpressionException;
    35  import javax.xml.xpath.XPathFactory;
    36
    37  import org.w3c.dom.Document;
    38  import org.xml.sax.SAXException;
    39
    40
    41  /***
    42   * XML utilities for document/xpath actions.
    43   *
    44   * @author gojomo
    45   * @version $Revision: 4644 $ $Date: 2006-09-20 22:40:21 +0000 (Wed, 20 Sep 2006) $
    46   */
    47  public class XmlUtils {
    48      public static Logger logger =
    49          Logger.getLogger(XmlUtils.class.getName());
    50
    51      /***
    52       * Parse a DOM Document from the given XML file.
    53       *
    54       * @param f File to parse as Document
    55       * @return Document
    56       * @throws IOException
    57       */
    58      public static Document getDocument(File f) throws IOException {
    59          DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
    60          factory.setNamespaceAware(true); // never forget this!
    61          try {
    62              DocumentBuilder builder = factory.newDocumentBuilder();
    63              return builder.parse(f);
    64          } catch (ParserConfigurationException e) {
    65              IOException ioe = new IOException();
    66              ioe.initCause(e);
    67              throw ioe;
    68          } catch (SAXException e) {
    69              IOException ioe = new IOException();
    70              ioe.initCause(e);
    71              throw ioe;
    72          }
    73      }
    74
    75      /***
    76       * Evaluate an XPath against a Document, returning a String.
    77       *
    78       * @param doc Document
    79       * @param xp XPath to evaluate against Document
    80       * @return String found at path or null
    81       */
    82      public static String xpathOrNull(Document doc, String xp) {
    83          XPathFactory factory = XPathFactory.newInstance();
    84          XPath xpath = factory.newXPath();
    85          try {
    86              XPathExpression expr = xpath.compile(xp);
    87              return expr.evaluate(doc);
    88          } catch (XPathExpressionException e) {
    89              return null;
    90          }
    91      }
    92  }