enhancement-engines/htmlextractor/src/main/java/org/apache/stanbol/enhancer/engines/htmlextractor/impl/DOMBuilder.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You 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 org.apache.stanbol.enhancer.engines.htmlextractor.impl;

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

import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.parsers.ParserConfigurationException;

import org.w3c.dom.Document;
import org.w3c.dom.Node;

/**
 *
 * @author <a href="mailto:kasper@dfki.de">Walter Kasper</a>
 * 
 */

public class DOMBuilder {
  /**
   * Returns a W3C DOM that exposes the same content as the supplied Jsoup document into a W3C DOM.
   * @param jsoupDocument The Jsoup document to convert.
   * @return A W3C Document.
   */
  public static Document jsoup2DOM(org.jsoup.nodes.Document jsoupDocument) {
    
    Document document = null;
    
    try {
      
      /* Obtain the document builder for the configured XML parser. */
      DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();
      DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();
      
      /* Create a document to contain the content. */
      document = docBuilder.newDocument();
      createDOM(jsoupDocument, document, document, new HashMap<String,String>());
      
    } catch (ParserConfigurationException pce) {
      throw new RuntimeException(pce);
    }
    
    return document;
  }
  
  /**
   * The internal helper that copies content from the specified Jsoup <tt>Node</tt> into a W3C {@link Node}.
   * @param node The Jsoup node containing the content to copy to the specified W3C {@link Node}.
   * @param out The W3C {@link Node} that receives the DOM content.
   */
  private static void createDOM(org.jsoup.nodes.Node node, Node out, Document doc, Map<String,String> ns) {
         
    if (node instanceof org.jsoup.nodes.Document) {
      
      org.jsoup.nodes.Document d = ((org.jsoup.nodes.Document) node);
      for (org.jsoup.nodes.Node n : d.childNodes()) {
        createDOM(n, out,doc,ns);
      }
      
    } else if (node instanceof org.jsoup.nodes.Element) {
      
      org.jsoup.nodes.Element e = ((org.jsoup.nodes.Element) node);
      org.w3c.dom.Element _e = doc.createElement(e.tagName());
      out.appendChild(_e);
      org.jsoup.nodes.Attributes atts = e.attributes();
      
      for(org.jsoup.nodes.Attribute a : atts){
        String attName = a.getKey();
        //omit xhtml namespace
        if (attName.equals("xmlns")) {
          continue;
        }
        String attPrefix = getNSPrefix(attName);
        if (attPrefix != null) {
          if (attPrefix.equals("xmlns")) {
            ns.put(getLocalName(attName), a.getValue());
          }
          else if (!attPrefix.equals("xml")) {
            String namespace = ns.get(attPrefix);
            if (namespace == null) {
              //fix attribute names looking like qnames
              attName = attName.replace(':','_');
            }
          }
        }
        _e.setAttribute(attName, a.getValue());
      }
      
      for (org.jsoup.nodes.Node n : e.childNodes()) {
        createDOM(n, _e, doc,ns);
      }
      
    } else if (node instanceof org.jsoup.nodes.TextNode) {
      
      org.jsoup.nodes.TextNode t = ((org.jsoup.nodes.TextNode) node);
      if (!(out instanceof Document)) {
        out.appendChild(doc.createTextNode(t.text()));
      }
    }
  }
  
  // some hacks for handling namespace in jsoup2DOM conversion
  private static String getNSPrefix(String name) {
    if (name != null) {
      int pos = name.indexOf(':');
      if (pos > 0) {
        return name.substring(0,pos);
      }
    }
    return null;
  }
  
  private static String getLocalName(String name) {
    if (name != null) {
      int pos = name.lastIndexOf(':');
      if (pos > 0) {
        return name.substring(pos+1);
      }
    }
    return name;
  }

}