001package org.apache.turbine.modules; 002 003/* 004 * Licensed to the Apache Software Foundation (ASF) under one 005 * or more contributor license agreements. See the NOTICE file 006 * distributed with this work for additional information 007 * regarding copyright ownership. The ASF licenses this file 008 * to you under the Apache License, Version 2.0 (the 009 * "License"); you may not use this file except in compliance 010 * with the License. You may obtain a copy of the License at 011 * 012 * http://www.apache.org/licenses/LICENSE-2.0 013 * 014 * Unless required by applicable law or agreed to in writing, 015 * software distributed under the License is distributed on an 016 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 017 * KIND, either express or implied. See the License for the 018 * specific language governing permissions and limitations 019 * under the License. 020 */ 021 022import java.util.ArrayList; 023import java.util.List; 024 025import org.apache.turbine.Turbine; 026import org.apache.turbine.TurbineConstants; 027import org.apache.turbine.pipeline.PipelineData; 028import org.apache.turbine.services.assemblerbroker.AssemblerBrokerService; 029import org.apache.turbine.services.assemblerbroker.TurbineAssemblerBroker; 030 031/** 032 * This is the base class for the loaders. It contains code that is 033 * used across all of the loaders. It also specifies the interface 034 * that is required to be called a Loader. 035 * 036 * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a> 037 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a> 038 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a> 039 * @param <T> the specialized assembler type 040 */ 041public abstract class GenericLoader<T extends Assembler> 042{ 043 /** The Assembler Broker Service */ 044 protected AssemblerBrokerService ab = TurbineAssemblerBroker.getService(); 045 046 /** @serial This can be serialized */ 047 private boolean reload = false; 048 049 /** Base packages path for Turbine */ 050 private static final String TURBINE_PACKAGE = "org.apache.turbine.modules"; 051 052 /** Packages paths for Turbine */ 053 private static List<String> TURBINE_PACKAGES = null; 054 055 /** 056 * Basic constructor for creating a loader. 057 */ 058 public GenericLoader() 059 { 060 super(); 061 } 062 063 /** 064 * Attempts to load and execute the external action that has been 065 * set. 066 * @param pipelineData the Turbine request 067 * @param name the name of the assembler module 068 * @exception Exception a generic exception. 069 */ 070 public abstract void exec(PipelineData pipelineData, String name) 071 throws Exception; 072 073 /** 074 * Returns whether or not this external action is reload itself. 075 * This is in cases where the Next button would be clicked, but 076 * since we are checking for that, we would go into an endless 077 * loop. 078 * 079 * @return True if the action is reload. 080 */ 081 public boolean reload() 082 { 083 return this.reload; 084 } 085 086 /** 087 * Sets whether or not this external action is reload itself. 088 * This is in cases where the Next button would be clicked, but 089 * since we are checking for that, we would go into an endless 090 * loop. 091 * 092 * @param reload True if the action must be marked as reload. 093 * @return Itself. 094 */ 095 public GenericLoader<T> setReload(boolean reload) 096 { 097 this.reload = reload; 098 return this; 099 } 100 101 /** 102 * Gets the base package where Turbine should find its default 103 * modules. 104 * 105 * @return A String with the base package name. 106 */ 107 public static String getBasePackage() 108 { 109 return TURBINE_PACKAGE; 110 } 111 112 /** 113 * Gets the package list where Turbine should find its 114 * modules. 115 * 116 * @return A List with the package names (including the base package). 117 */ 118 public static List<String> getPackages() 119 { 120 if (TURBINE_PACKAGES == null) 121 { 122 List<String> turbinePackages = new ArrayList<String>(); 123 List<Object> configTurbinePackages = 124 Turbine.getConfiguration() 125 .getList(TurbineConstants.MODULE_PACKAGES); 126 for (Object o : configTurbinePackages) 127 { 128 turbinePackages.add((String)o); 129 } 130 131 TURBINE_PACKAGES = turbinePackages; 132 } 133 134 List<String> packages = TURBINE_PACKAGES; 135 136 if (!packages.contains(TURBINE_PACKAGE)) 137 { 138 packages.add(TURBINE_PACKAGE); 139 } 140 141 return packages; 142 } 143 144 /** 145 * Pulls out an instance of the object by name. Name is just the 146 * single name of the object. 147 * 148 * @param type Type of the assembler. 149 * @param name Name of object instance. 150 * @return A Screen with the specified name, or null. 151 * @exception Exception a generic exception. 152 */ 153 protected T getAssembler(Class<T> type, String name) 154 throws Exception 155 { 156 T asm = null; 157 158 try 159 { 160 if (ab != null) 161 { 162 // Attempt to load the assembler 163 asm = ab.getAssembler(type, name); 164 } 165 } 166 catch (ClassCastException cce) 167 { 168 // This can alternatively let this exception be thrown 169 // So that the ClassCastException is shown in the 170 // browser window. Like this it shows "Screen not Found" 171 asm = null; 172 } 173 174 if (asm == null) 175 { 176 // If we did not find a screen we should try and give 177 // the user a reason for that... 178 // FIX ME: The AssemblerFactories should each add it's 179 // own string here... 180 List<String> packages = GenericLoader.getPackages(); 181 182 throw new ClassNotFoundException( 183 "\n\n\tRequested " + type + " not found: " + name + 184 "\n\tTurbine looked in the following " + 185 "modules.packages path: \n\t" + packages.toString() + "\n"); 186 } 187 188 return asm; 189 } 190}