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.TurbineServices; 29 import org.apache.turbine.services.assemblerbroker.AssemblerBrokerService; 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; 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 ab = (AssemblerBrokerService)TurbineServices.getInstance().getService(AssemblerBrokerService.SERVICE_NAME); 62 } 63 64 /** 65 * Attempts to load and execute the external action that has been 66 * set. 67 * @param pipelineData the Turbine request 68 * @param name the name of the assembler module 69 * @throws Exception a generic exception. 70 */ 71 public abstract void exec(PipelineData pipelineData, String name) 72 throws Exception; 73 74 /** 75 * Returns whether or not this external action is reload itself. 76 * This is in cases where the Next button would be clicked, but 77 * since we are checking for that, we would go into an endless 78 * loop. 79 * 80 * @return True if the action is reload. 81 */ 82 public boolean reload() 83 { 84 return this.reload; 85 } 86 87 /** 88 * Sets whether or not this external action is reload itself. 89 * This is in cases where the Next button would be clicked, but 90 * since we are checking for that, we would go into an endless 91 * loop. 92 * 93 * @param reload True if the action must be marked as reload. 94 * @return Itself. 95 */ 96 public GenericLoader<T> setReload(boolean reload) 97 { 98 this.reload = reload; 99 return this; 100 } 101 102 /** 103 * Gets the base package where Turbine should find its default 104 * modules. 105 * 106 * @return A String with the base package name. 107 */ 108 public static String getBasePackage() 109 { 110 return TURBINE_PACKAGE; 111 } 112 113 /** 114 * Gets the package list where Turbine should find its 115 * modules. 116 * 117 * @return A List with the package names (including the base package). 118 */ 119 public static List<String> getPackages() 120 { 121 if (TURBINE_PACKAGES == null) 122 { 123 List<String> turbinePackages = new ArrayList<String>(); 124 List<Object> configTurbinePackages = 125 Turbine.getConfiguration() 126 .getList(TurbineConstants.MODULE_PACKAGES); 127 for (Object o : configTurbinePackages) 128 { 129 turbinePackages.add((String)o); 130 } 131 132 TURBINE_PACKAGES = turbinePackages; 133 } 134 135 List<String> packages = TURBINE_PACKAGES; 136 137 if (!packages.contains(TURBINE_PACKAGE)) 138 { 139 packages.add(TURBINE_PACKAGE); 140 } 141 142 return packages; 143 } 144 145 /** 146 * Pulls out an instance of the object by name. Name is just the 147 * single name of the object. 148 * 149 * @param type Type of the assembler. 150 * @param name Name of object instance. 151 * @return A Screen with the specified name, or null. 152 * @throws Exception a generic exception. 153 */ 154 protected T getAssembler(Class<T> type, String name) 155 throws Exception 156 { 157 T asm = null; 158 159 try 160 { 161 if (ab != null) 162 { 163 // Attempt to load the assembler 164 asm = ab.getAssembler(type, name); 165 } 166 } 167 catch (ClassCastException cce) 168 { 169 // This can alternatively let this exception be thrown 170 // So that the ClassCastException is shown in the 171 // browser window. Like this it shows "Screen not Found" 172 asm = null; 173 } 174 175 if (asm == null) 176 { 177 // If we did not find a screen we should try and give 178 // the user a reason for that... 179 // FIX ME: The AssemblerFactories should each add it's 180 // own string here... 181 List<String> packages = GenericLoader.getPackages(); 182 183 throw new ClassNotFoundException( 184 "\n\n\tRequested " + type + " not found: " + name + 185 "\n\tTurbine looked in the following " + 186 "modules.packages path: \n\t" + packages.toString() + "\n"); 187 } 188 189 return asm; 190 } 191 }