serializerfactory.java

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/*
 * The Apache Software License, Version 1.1
 *
 *
 * Copyright (c) 1999 The Apache Software Foundation.  All rights 
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer. 
 *
 * 2. 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.
 *
 * 3. The end-user documentation included with the redistribution,
 *    if any, must include the following acknowledgment:  
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowledgment may appear in the software itself,
 *    if and wherever such third-party acknowledgments normally appear.
 *
 * 4. The names "Xerces" and "Apache Software Foundation" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written 
 *    permission, please contact [e-mail].
 *
 * 5. Products derived from this software may not be called "Apache",
 *    nor may "Apache" appear in their name, without prior written
 *    permission of the Apache Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED 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 APACHE SOFTWARE FOUNDATION OR
 * ITS 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.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation and was
 * originally based on software copyright (c) 1999, International
 * Business Machines, Inc., http://www.apache.org.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */


package org.jasig.portal.serialize;


import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.io.Writer;
import java.util.Hashtable;
import java.util.StringTokenizer;


/**
 *
 *
 * @version $Revision: 1.2 $ $Date: 2003/04/04 00:46:43 $
 * @author <a href="mailto:Scott_Boag/CAM/[e-mail]">Scott Boag</a>
 * @author <a href="mailto:[e-mail]">Assaf Arkin</a>
 */
public abstract class SerializerFactory
{


    public static final String FactoriesProperty = "org.jasig.apache.xml.serialize.factories";


    private static Hashtable  _factories = new Hashtable();


    static
    {
        SerializerFactory factory;
        String            list;
        StringTokenizer   token;
        String            className;
        
        // The default factories are always registered first,
        // any factory specified in the properties file and supporting
        // the same method will override the default factory.
        factory =  new SerializerFactoryImpl( Method.XML );
        registerSerializerFactory( factory );
        factory =  new SerializerFactoryImpl( Method.HTML );
        registerSerializerFactory( factory );
        factory =  new SerializerFactoryImpl( Method.XHTML );
        registerSerializerFactory( factory );
        factory =  new SerializerFactoryImpl( Method.TEXT );
        registerSerializerFactory( factory );
        
        list = System.getProperty( FactoriesProperty );
        if ( list != null ) {
            token = new StringTokenizer( list, " ;,:" );
            while ( token.hasMoreTokens() ) {
                className = token.nextToken();
                try {
                    factory = (SerializerFactory) Class.forName( className ).newInstance();
                    if ( _factories.containsKey( factory.getSupportedMethod() ) )
                        _factories.put( factory.getSupportedMethod(), factory );
                } catch ( Exception except ) { }
            }
        }
    }


    /**
     * Register a serializer factory, keyed by the given
     * method string.
     */
    public static void registerSerializerFactory( SerializerFactory factory )
    {
        String method;
        
        synchronized ( _factories ) {
            method = factory.getSupportedMethod();
            _factories.put( method, factory );
        }
    }


    /**
     * Register a serializer factory, keyed by the given
     * method string.
     */
    public static SerializerFactory getSerializerFactory( String method )
    {
        return (SerializerFactory) _factories.get( method );
    }


    /**
     * Returns the method supported by this factory and used to register
     * the factory. This call is required so factories can be added from
     * a properties file by knowing only the class name. This method is
     * protected, it is only required by this class but must be implemented
     * in derived classes.
     */
    protected abstract String getSupportedMethod();
    

    /**
     * Create a new serializer based on the {@link OutputFormat}.
     * If this method is used to create the serializer, the {@link
     * Serializer#setOutputByteStream} or {@link Serializer#setOutputCharStream}
     * methods must be called before serializing a document.
     */
    public abstract Serializer makeSerializer(OutputFormat format);


    /**
     * Create a new serializer, based on the {@link OutputFormat} and
     * using the writer as the output character stream.  If this
     * method is used, the encoding property will be ignored.
     */
    public abstract Serializer makeSerializer( Writer writer,
                                               OutputFormat format );
    
    
    /**
     * Create a new serializer, based on the {@link OutputFormat} and
     * using the output byte stream and the encoding specified in the
     * output format.
     *
     * @throws UnsupportedEncodingException The specified encoding is
     *   not supported
     */
    public abstract Serializer makeSerializer( OutputStream output,
                                               OutputFormat format )
        throws UnsupportedEncodingException;
    

}