xalan/transformer/SerializerSwitcher.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.
 */
/*
 * $Id: SerializerSwitcher.java 468645 2006-10-28 06:57:24Z minchau $
 */
package org.apache.xalan.transformer;

import java.io.OutputStream;
import java.io.Writer;
import java.util.Properties;

import javax.xml.transform.OutputKeys;
import javax.xml.transform.TransformerException;

import org.apache.xml.serializer.Serializer;
import org.apache.xml.serializer.SerializerFactory;
import org.apache.xml.serializer.Method;
import org.apache.xalan.templates.OutputProperties;

import org.xml.sax.ContentHandler;

/**
 * This is a helper class that decides if Xalan needs to switch
 * serializers, based on the first output element.
 */
public class SerializerSwitcher
{

  /**
   * Switch to HTML serializer if element is HTML
   *
   *
   * @param transformer Non-null transformer instance
   * @param ns Namespace URI of the element
   * @param localName Local part of name of element
   *
   * @throws TransformerException
   */
  public static void switchSerializerIfHTML(
          TransformerImpl transformer, String ns, String localName)
            throws TransformerException
  {

    if (null == transformer)
      return;

    if (((null == ns) || (ns.length() == 0))
            && localName.equalsIgnoreCase("html"))
    {
      // System.out.println("transformer.getOutputPropertyNoDefault(OutputKeys.METHOD): "+
      //              transformer.getOutputPropertyNoDefault(OutputKeys.METHOD));
      // Access at level of hashtable to see if the method has been set.
      if (null != transformer.getOutputPropertyNoDefault(OutputKeys.METHOD))
        return;

      // Getting the output properties this way won't cause a clone of
      // the properties.
      Properties prevProperties = transformer.getOutputFormat().getProperties();

      // We have to make sure we get an output properties with the proper
      // defaults for the HTML method.  The easiest way to do this is to
      // have the OutputProperties class do it.
      OutputProperties htmlOutputProperties = new OutputProperties(Method.HTML);

      htmlOutputProperties.copyFrom(prevProperties, true);
      Properties htmlProperties = htmlOutputProperties.getProperties();

      try
      {
//        Serializer oldSerializer = transformer.getSerializer();
        Serializer oldSerializer = null;

        if (null != oldSerializer)
        {
          Serializer serializer =
            SerializerFactory.getSerializer(htmlProperties);

          Writer writer = oldSerializer.getWriter();

          if (null != writer)
            serializer.setWriter(writer);
          else
          {
            OutputStream os = oldSerializer.getOutputStream();

            if (null != os)
              serializer.setOutputStream(os);
          }

//          transformer.setSerializer(serializer);

          ContentHandler ch = serializer.asContentHandler();

          transformer.setContentHandler(ch);
        }
      }
      catch (java.io.IOException e)
      {
        throw new TransformerException(e);
      }
    }
  }

  /**
   * Get the value of a property, without using the default properties.  This
   * can be used to test if a property has been explicitly set by the stylesheet
   * or user.
   *
   * @param name The property name, which is a fully-qualified URI.
   *
   * @return The value of the property, or null if not found.
   *
   * @throws IllegalArgumentException If the property is not supported,
   * and is not namespaced.
   */
  private static String getOutputPropertyNoDefault(String qnameString, Properties props)
    throws IllegalArgumentException
  {
    String value = (String)props.get(qnameString);

    return value;
  }

  /**
   * Switch to HTML serializer if element is HTML
   *
   *
   * @param ns Namespace URI of the element
   * @param localName Local part of name of element
   *
   * @throws TransformerException
   * @return new contentHandler.
   */
  public static Serializer switchSerializerIfHTML(
          String ns, String localName, Properties props, Serializer oldSerializer)
            throws TransformerException
  {
    Serializer newSerializer = oldSerializer;

    if (((null == ns) || (ns.length() == 0))
            && localName.equalsIgnoreCase("html"))
    {
      // System.out.println("transformer.getOutputPropertyNoDefault(OutputKeys.METHOD): "+
      //              transformer.getOutputPropertyNoDefault(OutputKeys.METHOD));
      // Access at level of hashtable to see if the method has been set.
      if (null != getOutputPropertyNoDefault(OutputKeys.METHOD, props))
        return newSerializer;

      // Getting the output properties this way won't cause a clone of
      // the properties.
      Properties prevProperties = props;

      // We have to make sure we get an output properties with the proper
      // defaults for the HTML method.  The easiest way to do this is to
      // have the OutputProperties class do it.
      OutputProperties htmlOutputProperties = new OutputProperties(Method.HTML);

      htmlOutputProperties.copyFrom(prevProperties, true);
      Properties htmlProperties = htmlOutputProperties.getProperties();

//      try
      {
        if (null != oldSerializer)
        {
          Serializer serializer =
            SerializerFactory.getSerializer(htmlProperties);

          Writer writer = oldSerializer.getWriter();

          if (null != writer)
            serializer.setWriter(writer);
          else
          {
            OutputStream os = serializer.getOutputStream();

            if (null != os)
              serializer.setOutputStream(os);
          }
          newSerializer = serializer;
        }
      }
//      catch (java.io.IOException e)
//      {
//        throw new TransformerException(e);
//      }
    }
    return newSerializer;
  }

}