XMLWriter.java

package org.cdlib.xtf.util;


/**
 * Copyright (c) 2004, Regents of the University of California
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * - Redistributions of source code must retain the above copyright notice,
 *   this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice,
 *   this list of conditions and the following disclaimer in the documentation
 *   and/or other materials provided with the distribution.
 * - Neither the name of the University of California nor the names of its
 *   contributors may be used to endorse or promote products derived from this
 *   software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
import java.io.StringWriter;
import java.util.Properties;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.stream.StreamResult;
import net.sf.saxon.FeatureKeys;
import net.sf.saxon.om.NodeInfo;

/**
 * Simple utility class that takes a Node or Source (representing an XML
 * document) and produces an indented string representation of it. This is
 * very useful for debugging.
 *
 * @author Martin Haye
 */
public class XMLWriter 
{
  /**
   * Prints the node, in XML format, to Trace.debug()
   */
  public static void debug(EasyNode node) {
    Trace.debug(toString(node, true));
  }

  /**
   * Prints the node, in XML format, to Trace.debug()
   */
  public static void debug(EasyNode node, boolean includeXMLDecl) {
    Trace.debug(toString(node, includeXMLDecl));
  }

  /**
   * Prints the node, in XML format, to Trace.debug()
   */
  public static void debug(Source node) {
    Trace.debug(toString(node, true));
  } // debugNode()

  /**
   * Prints the node, in XML format, to Trace.debug()
   */
  public static void debug(Source node, boolean includeXMLDecl) {
    Trace.debug(toString(node, includeXMLDecl));
  } // debugNode()

  /**
   * Format a nice, multi-line, indented, representation of the given
   * XML fragment.
   *
   * @param node  Base node to format.
   */
  public static String toString(EasyNode node) {
    return toString(node.getWrappedNode(), true);
  }

  /**
   * Format a nice, multi-line, indented, representation of the given
   * XML fragment.
   *
   * @param node  Base node to format.
   */
  public static String toString(EasyNode node, boolean includeXMLDecl) {
    return toString(node.getWrappedNode(), includeXMLDecl);
  }

  /**
   * Format a nice, multi-line, indented, representation of the given
   * XML fragment.
   *
   * @param node  Base node to format.
   */
  public static String toString(Source node) {
    return toString(node, true);
  }

  /**
   * Format a nice, multi-line, indented, representation of the given
   * XML fragment.
   *
   * @param node  Base node to format.
   * @param includeXMLDecl true to include XML declaration, false to
   *                       suppress it (useful for generating a fragment
   *                       of XML to insert within a larger document.)
   */
  public static String toString(Source node, boolean includeXMLDecl) 
  {
    try 
    {
      StringWriter writer = new StringWriter();
      StreamResult tmp = new StreamResult(writer);
      TransformerFactory factory = new net.sf.saxon.TransformerFactoryImpl();

      // Avoid NamePool translation, as it triggers a Saxon bug. 
      if (node instanceof NodeInfo) {
        factory.setAttribute(FeatureKeys.NAME_POOL,
                             ((NodeInfo)node).getNamePool());
      }

      Transformer trans = factory.newTransformer();
      Properties props = trans.getOutputProperties();
      props.put("indent", "yes");
      props.put("method", "xml");
      if (!includeXMLDecl)
        props.put("omit-xml-declaration", "yes");
      trans.setOutputProperties(props);

      // Make sure errors get directed to the right place.
      if (!(trans.getErrorListener() instanceof XTFSaxonErrorListener))
        trans.setErrorListener(new XTFSaxonErrorListener());

      trans.transform(node, tmp);
      return writer.toString();
    }
    catch (Exception e) {
      return "Error writing XML: " + e;
    }
  }
} // class XMLWriter