| /* |
| * $Id$ |
| * |
| * 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.tiles.extras.renderer; |
| |
| import java.io.IOException; |
| import java.util.List; |
| import java.util.concurrent.ConcurrentMap; |
| import java.util.concurrent.TimeUnit; |
| import java.util.regex.Matcher; |
| import java.util.regex.Pattern; |
| |
| import com.google.common.cache.CacheBuilder; |
| import com.google.common.cache.CacheLoader; |
| import org.apache.tiles.Attribute; |
| import org.apache.tiles.ListAttribute; |
| import org.apache.tiles.access.TilesAccess; |
| import org.apache.tiles.request.ApplicationContext; |
| import org.apache.tiles.request.Request; |
| import org.apache.tiles.request.render.Renderer; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * Provides a custom "options" syntax for attributes. |
| * The first option that can be rendered is. |
| * Comes from <a href="http://tech.finn.no/the-ultimate-view/">The Ultimate View</a> article.<p/> |
| * |
| * Actual rendering is delegated to the TypeDetectingRenderer that's supplied in the constructor.<p/> |
| * |
| * For example: |
| * "/WEB-INF/tiles/fragments/${options[myoptions]}/content.jsp" |
| * given the myptions list-attribute is defined like: |
| * <pre> |
| <put-list-attribute name="myoptions"> |
| <add-list-attribute> |
| <add-attribute value="car"/> |
| <add-attribute value="vechile"/> |
| <add-attribute value="advert"/> |
| </add-list-attribute> |
| </put-list-attribute> |
| </pre> |
| * will look for content.jsp <br/> |
| * first in "/WEB-INF/tiles/fragments/car/" then <br/> |
| * second in "/WEB-INF/tiles/fragments/vechile/" and <br/> |
| * last in "/WEB-INF/tiles/fragments/advert". |
| * <p/> |
| * <p/> |
| * Currently only supports one occurrance of such an "option" pattern in the attribute's value. |
| * <p/> |
| * Limitation: "looking" for templates is implemented using applicationContext.getResource(..) |
| * therefore the option values in the options list need to be visible as applicationResources. |
| * <p/> |
| * The attribute found and rendered is cached so to improve performance on subsequent lookups. |
| * The default cache time-to-live is {@value #DEFAULT_CACHE_LIFE}, specified by {@link #DEFAULT_CACHE_LIFE}. |
| * It can be customised by setting the system property {@value #CACHE_LIFE_PROPERTY}, see {@link #CACHE_LIFE_PROPERTY}. |
| * Setting it to zero will disable the cache. |
| */ |
| public final class OptionsRenderer implements Renderer { |
| |
| public static final String CACHE_LIFE_PROPERTY = OptionsRenderer.class.getName() + ".cache_ttl_ms"; |
| |
| public static final long DEFAULT_CACHE_LIFE = 1000 * 60 * 5; |
| |
| public static final Pattern OPTIONS_PATTERN |
| = Pattern.compile(Pattern.quote("{options[") + "(.+)" + Pattern.quote("]}")); |
| |
| private static final Logger LOG = LoggerFactory.getLogger(OptionsRenderer.class); |
| |
| private final ApplicationContext applicationContext; |
| private final Renderer renderer; |
| |
| public OptionsRenderer(final ApplicationContext applicationContext, final Renderer renderer) { |
| this.applicationContext = applicationContext; |
| this.renderer = renderer; |
| } |
| |
| @Override |
| public boolean isRenderable(final String path, final Request request) { |
| return renderer.isRenderable(path, request); |
| } |
| |
| @Override |
| public void render(final String path, final Request request) throws IOException { |
| |
| Matcher matcher = OPTIONS_PATTERN.matcher((String) path); |
| |
| if (null != matcher && matcher.find()) { |
| boolean done = false; |
| String match = matcher.group(1); |
| ListAttribute fallbacks = (ListAttribute) TilesAccess |
| .getCurrentContainer(request) |
| .getAttributeContext(request) |
| .getAttribute(match); |
| |
| if (null == fallbacks) { |
| throw new IllegalStateException("A matching list-attribute name=\"" + match + "\" must be defined."); |
| } else if (fallbacks.getValue().isEmpty()) { |
| throw new IllegalStateException( |
| "list-attribute name=\"" + match + "\" must have minimum one attribute"); |
| } |
| |
| for (Attribute option : (List<Attribute>) fallbacks.getValue()) { |
| String template = path.replaceFirst(Pattern.quote(matcher.group()), (String) option.getValue()); |
| done = renderAttempt(template, request); |
| if (done) { break; } |
| } |
| if (!done) { |
| throw new IOException("None of the options existed for " + path); |
| } |
| } else { |
| renderer.render(path, request); |
| } |
| } |
| |
| private boolean renderAttempt(final String template, final Request request) throws IOException { |
| boolean result = false; |
| if (Cache.attemptTemplate(template)) { |
| try { |
| if (null != applicationContext.getResource(template)) { |
| renderer.render(template, request); |
| result = true; |
| } |
| } catch (IOException ex) { |
| if (ex.getMessage().contains(template)) { |
| // expected outcome. continue loop. |
| LOG.trace(ex.getMessage()); |
| } else { |
| // comes from an inner templateAttribute.render(..) so throw on |
| throw ex; |
| } |
| } catch (RuntimeException ex) { |
| if (ex.getMessage().contains(template)) { |
| // expected outcome. continue loop. |
| LOG.trace(ex.getMessage()); |
| } else { |
| // comes from an inner templateAttribute.render(..) so throw on |
| throw ex; |
| } |
| } |
| Cache.update(template, result); |
| } |
| return result; |
| } |
| |
| private static final class Cache { |
| |
| private static final long CACHE_LIFE = Long.getLong(CACHE_LIFE_PROPERTY, DEFAULT_CACHE_LIFE); |
| |
| static { |
| LOG.info("cache_ttl_ms=" + CACHE_LIFE); |
| } |
| |
| /** It takes CACHE_LIFE milliseconds for any hot deployments to register. |
| */ |
| private static final ConcurrentMap<String,Boolean> TEMPLATE_EXISTS = CacheBuilder.newBuilder() |
| .expireAfterWrite(CACHE_LIFE, TimeUnit.MILLISECONDS) |
| .build( |
| new CacheLoader<String, Boolean>() { |
| @Override |
| public Boolean load(String key) { |
| throw new UnsupportedOperationException( |
| "illegal TEMPLATE_EXISTS.get(\"" + key |
| + "\") before TEMPLATE_EXISTS.containsKey(\"" + key + "\")"); |
| } |
| }) |
| .asMap(); |
| |
| static boolean attemptTemplate(final String template) { |
| return !TEMPLATE_EXISTS.containsKey(template) || TEMPLATE_EXISTS.get(template); |
| } |
| |
| static void update(final String template, final boolean found) { |
| TEMPLATE_EXISTS.putIfAbsent(template, found); |
| } |
| |
| private Cache() {} |
| } |
| } |