001package org.apache.turbine.services.assemblerbroker.util.java; 002 003 004import java.lang.reflect.InvocationTargetException; 005 006/* 007 * Licensed to the Apache Software Foundation (ASF) under one 008 * or more contributor license agreements. See the NOTICE file 009 * distributed with this work for additional information 010 * regarding copyright ownership. The ASF licenses this file 011 * to you under the Apache License, Version 2.0 (the 012 * "License"); you may not use this file except in compliance 013 * with the License. You may obtain a copy of the License at 014 * 015 * http://www.apache.org/licenses/LICENSE-2.0 016 * 017 * Unless required by applicable law or agreed to in writing, 018 * software distributed under the License is distributed on an 019 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 020 * KIND, either express or implied. See the License for the 021 * specific language governing permissions and limitations 022 * under the License. 023 */ 024 025import java.util.List; 026import java.util.concurrent.ConcurrentHashMap; 027 028import org.apache.commons.lang3.StringUtils; 029import org.apache.logging.log4j.LogManager; 030import org.apache.logging.log4j.Logger; 031import org.apache.turbine.modules.Assembler; 032import org.apache.turbine.modules.GenericLoader; 033import org.apache.turbine.modules.Loader; 034import org.apache.turbine.services.assemblerbroker.util.AssemblerFactory; 035 036/** 037 * A screen factory that attempts to load a java class from 038 * the module packages defined in the TurbineResource.properties. 039 * 040 * @author <a href="mailto:leon@opticode.co.za">Leon Messerschmidt</a> 041 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a> 042 * @param <T> the specialized assembler type 043 */ 044public abstract class JavaBaseFactory<T extends Assembler> 045 implements AssemblerFactory<T> 046{ 047 /** A vector of packages. */ 048 private static List<String> packages = GenericLoader.getPackages(); 049 050 /** Logging */ 051 protected Logger log = LogManager.getLogger(this.getClass()); 052 053 /** 054 * A cache for previously obtained Class instances, which we keep in order 055 * to reduce the Class.forName() overhead (which can be sizable). 056 */ 057 private final ConcurrentHashMap<String, Class<T>> classCache = new ConcurrentHashMap<>(); 058 059 /** 060 * Get an Assembler. 061 * 062 * @param packageName java package name 063 * @param name name of the requested Assembler 064 * @return an Assembler 065 */ 066 @SuppressWarnings("unchecked") 067 public T getAssembler(String packageName, String name) 068 { 069 T assembler = null; 070 071 log.debug("Class Fragment is {}", name); 072 073 if (StringUtils.isNotEmpty(name)) 074 { 075 for (String p : packages) 076 { 077 StringBuilder sb = new StringBuilder(); 078 079 sb.append(p).append('.').append(packageName).append('.').append(name); 080 String className = sb.toString(); 081 082 log.debug("Trying {}", className); 083 084 try 085 { 086 Class<T> servClass = classCache.get(className); 087 if (servClass == null) 088 { 089 servClass = (Class<T>) Class.forName(className); 090 Class<T> _servClass = classCache.putIfAbsent(className, servClass); 091 if (_servClass != null) 092 { 093 servClass = _servClass; 094 } 095 } 096 assembler = servClass.getDeclaredConstructor().newInstance(); 097 break; // for() 098 } 099 catch (ClassNotFoundException cnfe) 100 { 101 // Do this so we loop through all the packages. 102 log.debug("{}: Not found", className); 103 } 104 catch (NoClassDefFoundError ncdfe) 105 { 106 // Do this so we loop through all the packages. 107 log.debug("{}: No Class Definition found", className); 108 } 109 // With ClassCastException, InstantiationException we hit big problems 110 catch (ClassCastException | InstantiationException | IllegalAccessException | InvocationTargetException | NoSuchMethodException e) 111 { 112 // This means trouble! 113 // Alternatively we can throw this exception so 114 // that it will appear on the client browser 115 log.error("Could not load {}", className, e); 116 break; // for() 117 } 118 } 119 } 120 121 log.debug("Returning: {}", assembler); 122 123 return assembler; 124 } 125 126 /** 127 * Get the loader for this type of assembler 128 * 129 * @return a Loader 130 */ 131 @Override 132 public abstract Loader<T> getLoader(); 133 134 /** 135 * Get the size of a possibly configured cache 136 * 137 * @return the size of the cache in bytes 138 */ 139 @Override 140 public int getCacheSize() 141 { 142 return getLoader().getCacheSize(); 143 } 144}