001/* 002 * (C) Copyright 2006-2011 Nuxeo SA (http://nuxeo.com/) and others. 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 * 016 * Contributors: 017 * bstefanescu 018 */ 019package org.nuxeo.ecm.automation.core.rendering; 020 021import java.io.IOException; 022import java.io.InputStream; 023import java.net.URL; 024import java.util.Collections; 025import java.util.LinkedHashMap; 026import java.util.Map; 027 028import org.mvel2.templates.CompiledTemplate; 029import org.mvel2.templates.TemplateCompiler; 030import org.mvel2.templates.TemplateRuntime; 031import org.nuxeo.common.utils.FileUtils; 032import org.nuxeo.ecm.automation.OperationException; 033import org.nuxeo.runtime.api.Framework; 034import org.nuxeo.runtime.services.resource.ResourceService; 035 036/** 037 * MVEL rendering using a simple cache of compiled template. 038 * 039 * @author <a href="mailto:bs@nuxeo.com">Bogdan Stefanescu</a> 040 */ 041public class MvelRender implements Renderer { 042 043 protected Map<String, CompiledTemplate> cache = Collections.synchronizedMap(new Cache()); 044 045 @Override 046 public String render(String uriOrContent, Map<String, Object> root) throws OperationException, IOException { 047 CompiledTemplate compiled = null; 048 String content = null; 049 if (uriOrContent.startsWith(Renderer.TEMPLATE_PREFIX)) { 050 String name = uriOrContent.substring(Renderer.TEMPLATE_PREFIX.length()); 051 compiled = cache.get(name); 052 if (compiled == null) { 053 URL url = Framework.getService(ResourceService.class).getResource(name); 054 if (url == null) { 055 throw new OperationException("Rendering resource not found: " + name); 056 } 057 InputStream in = url.openStream(); 058 try { 059 content = FileUtils.read(in); 060 } finally { 061 in.close(); 062 } 063 compiled = TemplateCompiler.compileTemplate(content); 064 cache.put(name, compiled); 065 } 066 } else { 067 content = uriOrContent; 068 compiled = TemplateCompiler.compileTemplate(content); 069 } 070 071 Object obj = TemplateRuntime.execute(compiled, root); 072 return obj == null ? "" : obj.toString(); 073 } 074 075 @SuppressWarnings("serial") 076 private static class Cache extends LinkedHashMap<String, CompiledTemplate> { 077 078 protected int maxCachedItems; 079 080 private Cache() { 081 this(128); 082 } 083 084 private Cache(int maxCachedItems) { 085 super(maxCachedItems, 1.0f, true); 086 this.maxCachedItems = maxCachedItems; 087 } 088 089 @Override 090 protected boolean removeEldestEntry(Map.Entry<String, CompiledTemplate> eldest) { 091 return size() > maxCachedItems; 092 } 093 094 } 095 096}