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.TurbineServices; 029import org.apache.turbine.services.assemblerbroker.AssemblerBrokerService; 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; 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 ab = (AssemblerBrokerService)TurbineServices.getInstance().getService(AssemblerBrokerService.SERVICE_NAME); 062 } 063 064 /** 065 * Attempts to load and execute the external action that has been 066 * set. 067 * @param pipelineData the Turbine request 068 * @param name the name of the assembler module 069 * @throws Exception a generic exception. 070 */ 071 public abstract void exec(PipelineData pipelineData, String name) 072 throws Exception; 073 074 /** 075 * Returns whether or not this external action is reload itself. 076 * This is in cases where the Next button would be clicked, but 077 * since we are checking for that, we would go into an endless 078 * loop. 079 * 080 * @return True if the action is reload. 081 */ 082 public boolean reload() 083 { 084 return this.reload; 085 } 086 087 /** 088 * Sets whether or not this external action is reload itself. 089 * This is in cases where the Next button would be clicked, but 090 * since we are checking for that, we would go into an endless 091 * loop. 092 * 093 * @param reload True if the action must be marked as reload. 094 * @return Itself. 095 */ 096 public GenericLoader<T> setReload(boolean reload) 097 { 098 this.reload = reload; 099 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}