| /* |
| * Copyright (c) 2003 The Visigoth Software Society. 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 acknowledgement: |
| * "This product includes software developed by the |
| * Visigoth Software Society (http://www.visigoths.org/)." |
| * Alternately, this acknowledgement may appear in the software itself, |
| * if and wherever such third-party acknowledgements normally appear. |
| * |
| * 4. Neither the name "FreeMarker", "Visigoth", nor any of the names of the |
| * project contributors may be used to endorse or promote products derived |
| * from this software without prior written permission. For written |
| * permission, please contact visigoths@visigoths.org. |
| * |
| * 5. Products derived from this software may not be called "FreeMarker" or "Visigoth" |
| * nor may "FreeMarker" or "Visigoth" appear in their names |
| * without prior written permission of the Visigoth Software Society. |
| * |
| * 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 VISIGOTH SOFTWARE SOCIETY 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 Visigoth Software Society. For more |
| * information on the Visigoth Software Society, please see |
| * http://www.visigoths.org/ |
| */ |
| |
| package freemarker.cache; |
| |
| import java.io.IOException; |
| import java.io.Reader; |
| import java.util.Collections; |
| import java.util.HashMap; |
| import java.util.Map; |
| |
| /** |
| * A {@link TemplateLoader} that uses a set of other loaders to load the templates. |
| * On every request, loaders are queried in the order of their appearance in the |
| * array of loaders provided to the constructor. However, if a request for some template |
| * name was already satisfied in the past by one of the loaders, that Loader is queried |
| * first (a soft affinity). |
| * |
| * <p>This class is <em>not</em> thread-safe. If it's accessed from multiple |
| * threads concurrently, proper synchronization must be provided by the callers. |
| * Note that {@link TemplateCache}, the natural user of this class, provides the |
| * necessary synchronizations when it uses this class, so then you don't have to worry |
| * this. |
| * |
| * @author Attila Szegedi, szegedia at freemail dot hu |
| */ |
| public class MultiTemplateLoader implements StatefulTemplateLoader |
| { |
| private final TemplateLoader[] loaders; |
| private final Map lastLoaderForName = Collections.synchronizedMap(new HashMap()); |
| |
| /** |
| * Creates a new multi template Loader that will use the specified loaders. |
| * @param loaders the loaders that are used to load templates. |
| */ |
| public MultiTemplateLoader(TemplateLoader[] loaders) |
| { |
| this.loaders = (TemplateLoader[])loaders.clone(); |
| } |
| |
| public Object findTemplateSource(String name) |
| throws |
| IOException |
| { |
| // Use soft affinity - give the loader that last found this |
| // resource a chance to find it again first. |
| TemplateLoader lastLoader = (TemplateLoader)lastLoaderForName.get(name); |
| if(lastLoader != null) |
| { |
| Object source = lastLoader.findTemplateSource(name); |
| if(source != null) |
| { |
| return new MultiSource(source, lastLoader); |
| } |
| } |
| |
| // If there is no affine loader, or it could not find the resource |
| // again, try all loaders in order of appearance. If any manages |
| // to find the resource, then associate it as the new affine loader |
| // for this resource. |
| for(int i = 0; i < loaders.length; ++i) |
| { |
| TemplateLoader loader = loaders[i]; |
| Object source = loader.findTemplateSource(name); |
| if(source != null) |
| { |
| lastLoaderForName.put(name, loader); |
| return new MultiSource(source, loader); |
| } |
| } |
| |
| lastLoaderForName.remove(name); |
| // Resource not found |
| return null; |
| } |
| |
| public long getLastModified(Object templateSource) |
| { |
| return ((MultiSource)templateSource).getLastModified(); |
| } |
| |
| public Reader getReader(Object templateSource, String encoding) |
| throws |
| IOException |
| { |
| return ((MultiSource)templateSource).getReader(encoding); |
| } |
| |
| public void closeTemplateSource(Object templateSource) |
| throws |
| IOException |
| { |
| ((MultiSource)templateSource).close(); |
| } |
| |
| public void resetState() |
| { |
| lastLoaderForName.clear(); |
| for (int i = 0; i < loaders.length; i++) { |
| TemplateLoader loader = loaders[i]; |
| if(loader instanceof StatefulTemplateLoader) { |
| ((StatefulTemplateLoader)loader).resetState(); |
| } |
| } |
| } |
| |
| /** |
| * Represents a template source bound to a specific template loader. It |
| * serves as the complete template source descriptor used by the |
| * MultiTemplateLoader class. |
| */ |
| private static final class MultiSource |
| { |
| private final Object source; |
| private final TemplateLoader loader; |
| |
| MultiSource(Object source, TemplateLoader loader) |
| { |
| this.source = source; |
| this.loader = loader; |
| } |
| |
| long getLastModified() |
| { |
| return loader.getLastModified(source); |
| } |
| |
| Reader getReader(String encoding) |
| throws |
| IOException |
| { |
| return loader.getReader(source, encoding); |
| } |
| |
| void close() |
| throws |
| IOException |
| { |
| loader.closeTemplateSource(source); |
| } |
| |
| public boolean equals(Object o) { |
| if(o instanceof MultiSource) { |
| MultiSource m = (MultiSource)o; |
| return m.loader.equals(loader) && m.source.equals(source); |
| } |
| return false; |
| } |
| |
| public int hashCode() { |
| return loader.hashCode() + 31 * source.hashCode(); |
| } |
| |
| public String toString() { |
| return source.toString(); |
| } |
| } |
| } |