OdfTextExtractor.java

/**
 * **********************************************************************
 *
 * <p>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
 *
 * <p>http://www.apache.org/licenses/LICENSE-2.0
 *
 * <p>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.
 *
 * <p>**********************************************************************
 */
package org.odftoolkit.odfdom.incubator.doc.text;

import org.odftoolkit.odfdom.dom.DefaultElementVisitor;
import org.odftoolkit.odfdom.dom.OdfDocumentNamespace;
import org.odftoolkit.odfdom.dom.element.text.TextHElement;
import org.odftoolkit.odfdom.dom.element.text.TextLineBreakElement;
import org.odftoolkit.odfdom.dom.element.text.TextPElement;
import org.odftoolkit.odfdom.dom.element.text.TextSElement;
import org.odftoolkit.odfdom.dom.element.text.TextTabElement;
import org.odftoolkit.odfdom.pkg.OdfElement;
import org.w3c.dom.Node;

/**
 * It's a sub class of DefaultElementVisitor. It provides a method to get the display text of a
 * single element.
 *
 * <p>If you pass the content root as the parameter, the whole document content will be returned,
 * without any tag information.
 *
 * <p>It implements part of white space handling fuctions: text:p, text:h, text:s, text:tab,
 * text:linebreak are processed according to ODF specification.
 */
public class OdfTextExtractor extends DefaultElementVisitor {

  protected StringBuilder mTextBuilder;
  OdfElement mElement;
  protected static final char NewLineChar = '\r';
  protected static final char TabChar = '\t';

  /** Default constructor */
  protected OdfTextExtractor() {}

  /**
   * Constructor with an ODF element as paramter
   *
   * @param element the ODF element whose text would be extracted.
   */
  protected OdfTextExtractor(OdfElement element) {
    mTextBuilder = new StringBuilder();
    mElement = element;
  }

  /**
   * Append the text content of this element to string buffer.
   *
   * @param ele the ODF element whose text will be appended.
   */
  protected void appendElementText(OdfElement ele) {
    Node node = ele.getFirstChild();

    while (node != null) {
      if (node.getNodeType() == Node.TEXT_NODE) {
        mTextBuilder.append(node.getNodeValue());
      } else if (node.getNodeType() == Node.ELEMENT_NODE) {
        OdfElement element = (OdfElement) node;
        element.accept(this);
      }
      node = node.getNextSibling();
    }
  }

  /**
   * An instance of OdfTextExtractor will be created to extract the text content of an ODF element.
   *
   * @param element the ODF element whose text will be extracted.
   * @return An instance of OdfTextExtractor
   */
  public static OdfTextExtractor newOdfTextExtractor(OdfElement element) {
    return new OdfTextExtractor(element);
  }

  /* (non-Javadoc)
   * @see org.odftoolkit.odfdom.dom.DefaultElementVisitor#visit(org.odftoolkit.odfdom.pkg.OdfElement)
   */
  @Override
  public void visit(OdfElement element) {
    if (element.getNamespaceURI().equals(OdfDocumentNamespace.META.getUri())
        || element.getNamespaceURI().equals(OdfDocumentNamespace.DC.getUri())) {
      mTextBuilder.append(NewLineChar);
    }
    appendElementText(element);
  }

  /* (non-Javadoc)
   * @see org.odftoolkit.odfdom.dom.DefaultElementVisitor#visit(org.odftoolkit.odfdom.dom.element.text.TextPElement)
   */
  @Override
  public void visit(TextPElement ele) {
    mTextBuilder.append(NewLineChar);
    appendElementText(ele);
  }

  /* (non-Javadoc)
   * @see org.odftoolkit.odfdom.dom.DefaultElementVisitor#visit(org.odftoolkit.odfdom.dom.element.text.TextHElement)
   */
  @Override
  public void visit(TextHElement ele) {
    mTextBuilder.append(NewLineChar);
    appendElementText(ele);
  }

  /* (non-Javadoc)
   * @see org.odftoolkit.odfdom.dom.DefaultElementVisitor#visit(org.odftoolkit.odfdom.dom.element.text.TextSElement)
   */
  @Override
  public void visit(TextSElement ele) {
    Integer count = ele.getTextCAttribute();
    if (count == null) {
      count = 1;
    }
    for (int i = 0; i < count; i++) {
      mTextBuilder.append(' ');
    }
  }

  /* (non-Javadoc)
   * @see org.odftoolkit.odfdom.dom.DefaultElementVisitor#visit(org.odftoolkit.odfdom.dom.element.text.TextTabElement)
   */
  @Override
  public void visit(TextTabElement ele) {
    mTextBuilder.append(TabChar);
  }

  /* (non-Javadoc)
   * @see org.odftoolkit.odfdom.dom.DefaultElementVisitor#visit(org.odftoolkit.odfdom.dom.element.text.TextLineBreakElement)
   */
  @Override
  public void visit(TextLineBreakElement ele) {
    mTextBuilder.append(NewLineChar);
    appendElementText(ele);
  }

  /**
   * Return the text content as a string
   *
   * @return the text content as a string
   */
  public String getText() {
    visit(mElement);
    return mTextBuilder.toString();
  }
}