001 package 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 */ 021 022 import java.util.List; 023 024 import org.apache.turbine.Turbine; 025 import org.apache.turbine.TurbineConstants; 026 import org.apache.turbine.pipeline.PipelineData; 027 import org.apache.turbine.services.assemblerbroker.AssemblerBrokerService; 028 import org.apache.turbine.services.assemblerbroker.TurbineAssemblerBroker; 029 import org.apache.turbine.util.RunData; 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 * @version $Id: GenericLoader.java 1078552 2011-03-06 19:58:46Z tv $ 040 */ 041 public 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 * Should revert to abstract when RunData has gone. 067 * @exception Exception a generic exception. 068 */ 069 public void exec(PipelineData pipelineData, String name) 070 throws Exception 071 { 072 RunData data = getRunData(pipelineData); 073 exec(data, name); 074 } 075 076 077 /** 078 * Attempts to load and execute the external action that has been 079 * set. 080 * @deprecated Use of this method should be avoided. Use 081 * <code>exec(PipelineData data, String name)</code> instead. 082 * @exception Exception a generic exception. 083 */ 084 @Deprecated 085 public abstract void exec(RunData data, String name) 086 throws Exception; 087 088 /** 089 * Commented out. 090 * This method should return the complete classpath + name. 091 * 092 * @param name 093 * @return 094 * 095 public abstract String getClassName(String name); 096 */ 097 098 /** 099 * Returns whether or not this external action is reload itself. 100 * This is in cases where the Next button would be clicked, but 101 * since we are checking for that, we would go into an endless 102 * loop. 103 * 104 * @return True if the action is reload. 105 */ 106 public boolean reload() 107 { 108 return this.reload; 109 } 110 111 /** 112 * Sets whether or not this external action is reload itself. 113 * This is in cases where the Next button would be clicked, but 114 * since we are checking for that, we would go into an endless 115 * loop. 116 * 117 * @param reload True if the action must be marked as reload. 118 * @return Itself. 119 */ 120 public GenericLoader setReload(boolean reload) 121 { 122 this.reload = reload; 123 return this; 124 } 125 126 /** 127 * Gets the base package where Turbine should find its default 128 * modules. 129 * 130 * @return A String with the base package name. 131 */ 132 public static String getBasePackage() 133 { 134 return TURBINE_PACKAGE; 135 } 136 137 /** 138 * Gets the package list where Turbine should find its 139 * modules. 140 * 141 * @return A List with the package names (including the base package). 142 */ 143 @SuppressWarnings("unchecked") 144 public static List<String> getPackages() 145 { 146 if (TURBINE_PACKAGES == null) 147 { 148 TURBINE_PACKAGES = 149 Turbine.getConfiguration().getList(TurbineConstants.MODULE_PACKAGES); 150 } 151 152 List<String> packages = TURBINE_PACKAGES; 153 154 if (!packages.contains(TURBINE_PACKAGE)) 155 { 156 packages.add(TURBINE_PACKAGE); 157 } 158 159 return packages; 160 } 161 162 /** 163 * Pulls out an instance of the object by name. Name is just the 164 * single name of the object. 165 * 166 * @param type Type of the assembler. 167 * @param name Name of object instance. 168 * @return A Screen with the specified name, or null. 169 * @exception Exception a generic exception. 170 */ 171 protected T getAssembler(String type, String name) 172 throws Exception 173 { 174 T asm = null; 175 176 try 177 { 178 if (ab != null) 179 { 180 // Attempt to load the assembler 181 asm = (T) ab.getAssembler(type, name); 182 } 183 } 184 catch (ClassCastException cce) 185 { 186 // This can alternatively let this exception be thrown 187 // So that the ClassCastException is shown in the 188 // browser window. Like this it shows "Screen not Found" 189 asm = null; 190 } 191 192 if (asm == null) 193 { 194 // If we did not find a screen we should try and give 195 // the user a reason for that... 196 // FIX ME: The AssemblerFactories should each add it's 197 // own string here... 198 List<String> packages = GenericLoader.getPackages(); 199 200 throw new ClassNotFoundException( 201 "\n\n\tRequested " + type + " not found: " + name + 202 "\n\tTurbine looked in the following " + 203 "modules.packages path: \n\t" + packages.toString() + "\n"); 204 } 205 206 return asm; 207 } 208 209 /** 210 * Helper method to cast from PipelineData to RunData. This will go when 211 * the pipeline is fully implemented and the RunData-methods are removed 212 * 213 * @param pipelineData a PipelineData object 214 * 215 * @return the input object casted to RunData 216 */ 217 private RunData getRunData(PipelineData pipelineData) 218 { 219 if(!(pipelineData instanceof RunData)) 220 { 221 throw new RuntimeException("Can't cast to rundata from pipeline data."); 222 } 223 return (RunData)pipelineData; 224 } 225 }