RELEASE_2_1_13/src/blocks/batik/java/org/apache/cocoon/components/transcoder/ExtendableTranscoderFactory.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.cocoon.components.transcoder;

import org.apache.batik.transcoder.Transcoder;
import org.apache.batik.transcoder.image.JPEGTranscoder;
import org.apache.batik.transcoder.image.PNGTranscoder;
import org.apache.batik.transcoder.image.TIFFTranscoder;

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

/**
 * An extendable Batik Transcoder factory.
 * When given a MIME type, find a Transcoder which supports that MIME
 * type. This factory is extendable as new <code>Transcoder</code>s can
 * be added at runtime.
 *
 * @author <a href="mailto:rossb@apache.org">Ross Burton</a>
 * @version CVS $Id$
 */
public class ExtendableTranscoderFactory implements TranscoderFactory {

    protected final static Map transcoders = new HashMap();

    protected final static TranscoderFactory singleton = new ExtendableTranscoderFactory();

    private ExtendableTranscoderFactory() {
        // Add the default transcoders which come with Batik
        addTranscoder("image/jpeg", JPEGTranscoder.class);
        addTranscoder("image/jpg", JPEGTranscoder.class);
        addTranscoder("image/png", PNGTranscoder.class);
        addTranscoder("image/tiff", TIFFTranscoder.class);
    }

    /**
     * Get a reference to this Transcoder Factory.
     */
    public final static TranscoderFactory getTranscoderFactoryImplementation() {
        return singleton;
    }

    /**
     * Create a transcoder for a specified MIME type.
     * @param mimeType The MIME type of the destination format
     * @return A suitable transcoder, or <code>null</code> if one cannot be found
     */
    public Transcoder createTranscoder(String mimeType) {
        Class transcoderClass = (Class) transcoders.get(mimeType);
        if (transcoderClass == null) {
            return null;
        } else {
            try {
                return (Transcoder) transcoderClass.newInstance();
            } catch (Exception ex) {
                return null;
            }
        }
    }

    /**
     * Add a mapping from the specified MIME type to a transcoder.
     * Note: The transcoder must have a no-argument constructor.
     * @param mimeType The MIME type of the Transcoder
     * @param transcoderClass The <code>Class</code> object for the Transcoder.
     */
    public void addTranscoder(String mimeType, Class transcoderClass) {
        transcoders.put(mimeType, transcoderClass);
    }

    /**
     * Remove the mapping from a specified MIME type.
     * @param mimeType The MIME type to remove from the mapping.
     */
    public void removeTranscoder(String mimeType) {
        transcoders.remove(mimeType);
    }
}