1 package org.apache.turbine.modules; 2 3 /* 4 * Licensed to the Apache Software Foundation (ASF) under one 5 * or more contributor license agreements. See the NOTICE file 6 * distributed with this work for additional information 7 * regarding copyright ownership. The ASF licenses this file 8 * to you under the Apache License, Version 2.0 (the 9 * "License"); you may not use this file except in compliance 10 * with the License. You may obtain a copy of the License at 11 * 12 * http://www.apache.org/licenses/LICENSE-2.0 13 * 14 * Unless required by applicable law or agreed to in writing, 15 * software distributed under the License is distributed on an 16 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 17 * KIND, either express or implied. See the License for the 18 * specific language governing permissions and limitations 19 * under the License. 20 */ 21 22 import java.util.ArrayList; 23 import java.util.List; 24 25 import org.apache.turbine.Turbine; 26 import org.apache.turbine.TurbineConstants; 27 import org.apache.turbine.pipeline.PipelineData; 28 import org.apache.turbine.services.assemblerbroker.AssemblerBrokerService; 29 import org.apache.turbine.services.assemblerbroker.TurbineAssemblerBroker; 30 31 /** 32 * This is the base class for the loaders. It contains code that is 33 * used across all of the loaders. It also specifies the interface 34 * that is required to be called a Loader. 35 * 36 * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a> 37 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a> 38 * @author <a href="mailto:peter@courcoux.biz">Peter Courcoux</a> 39 * @param <T> the specialized assembler type 40 */ 41 public abstract class GenericLoader<T extends Assembler> 42 { 43 /** The Assembler Broker Service */ 44 protected AssemblerBrokerService ab = TurbineAssemblerBroker.getService(); 45 46 /** @serial This can be serialized */ 47 private boolean reload = false; 48 49 /** Base packages path for Turbine */ 50 private static final String TURBINE_PACKAGE = "org.apache.turbine.modules"; 51 52 /** Packages paths for Turbine */ 53 private static List<String> TURBINE_PACKAGES = null; 54 55 /** 56 * Basic constructor for creating a loader. 57 */ 58 public GenericLoader() 59 { 60 super(); 61 } 62 63 /** 64 * Attempts to load and execute the external action that has been 65 * set. 66 * @param pipelineData the Turbine request 67 * @param name the name of the assembler module 68 * @exception Exception a generic exception. 69 */ 70 public abstract void exec(PipelineData pipelineData, String name) 71 throws Exception; 72 73 /** 74 * Returns whether or not this external action is reload itself. 75 * This is in cases where the Next button would be clicked, but 76 * since we are checking for that, we would go into an endless 77 * loop. 78 * 79 * @return True if the action is reload. 80 */ 81 public boolean reload() 82 { 83 return this.reload; 84 } 85 86 /** 87 * Sets whether or not this external action is reload itself. 88 * This is in cases where the Next button would be clicked, but 89 * since we are checking for that, we would go into an endless 90 * loop. 91 * 92 * @param reload True if the action must be marked as reload. 93 * @return Itself. 94 */ 95 public GenericLoader<T> setReload(boolean reload) 96 { 97 this.reload = reload; 98 return this; 99 } 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 }