| /* |
| * 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. |
| */ |
| |
| /* $Id$ */ |
| |
| package org.apache.xmlgraphics.image.loader.impl; |
| |
| import java.io.IOException; |
| import java.util.Map; |
| |
| import org.apache.commons.logging.Log; |
| import org.apache.commons.logging.LogFactory; |
| |
| import org.apache.xmlgraphics.image.loader.Image; |
| import org.apache.xmlgraphics.image.loader.ImageException; |
| import org.apache.xmlgraphics.image.loader.ImageFlavor; |
| import org.apache.xmlgraphics.image.loader.ImageInfo; |
| import org.apache.xmlgraphics.image.loader.ImageSessionContext; |
| import org.apache.xmlgraphics.image.loader.spi.ImageLoader; |
| |
| /** |
| * Composite ImageLoader implementation in order to provide fallbacks when one ImageLoader |
| * fails due to some limitation. |
| */ |
| public class CompositeImageLoader extends AbstractImageLoader { |
| |
| /** logger */ |
| protected static Log log = LogFactory.getLog(CompositeImageLoader.class); |
| |
| private ImageLoader[] loaders; |
| |
| /** |
| * Main constructor. |
| * @param loaders the contained image loaders |
| */ |
| public CompositeImageLoader(ImageLoader[] loaders) { |
| if (loaders == null || loaders.length == 0) { |
| throw new IllegalArgumentException("Must at least pass one ImageLoader as parameter"); |
| } |
| for (int i = 1, c = loaders.length; i < c; i++) { |
| if (!loaders[0].getTargetFlavor().equals(loaders[i].getTargetFlavor())) { |
| throw new IllegalArgumentException( |
| "All ImageLoaders must produce the same target flavor"); |
| } |
| } |
| this.loaders = loaders; |
| } |
| |
| /** {@inheritDoc} */ |
| public ImageFlavor getTargetFlavor() { |
| return loaders[0].getTargetFlavor(); |
| } |
| |
| /** {@inheritDoc} */ |
| public Image loadImage(ImageInfo info, Map hints, ImageSessionContext session) |
| throws ImageException, IOException { |
| ImageException firstException = null; |
| for (int i = 0, c = this.loaders.length; i < c; i++) { |
| ImageLoader loader = this.loaders[i]; |
| try { |
| Image img = loader.loadImage(info, hints, session); |
| if (img != null && firstException != null) { |
| log.debug("First ImageLoader failed (" + firstException.getMessage() |
| + "). Fallback was successful."); |
| } |
| return img; |
| } catch (ImageException ie) { |
| if (firstException == null) { |
| firstException = ie; |
| } |
| } |
| } |
| throw firstException; |
| } |
| |
| /** {@inheritDoc} */ |
| public String toString() { |
| StringBuffer sb = new StringBuffer("["); |
| for (int i = 0; i < this.loaders.length; i++) { |
| if (i > 0) { |
| sb.append(","); |
| } |
| sb.append(this.loaders[i].toString()); |
| } |
| sb.append("]"); |
| return sb.toString(); |
| } |
| |
| } |