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org.apache.turbine.modules.ScreenLoader |
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1 | package org.apache.turbine.modules; |
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2 | ||
3 | /* |
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4 | * Copyright 2001-2004 The Apache Software Foundation. |
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5 | * |
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6 | * Licensed under the Apache License, Version 2.0 (the "License") |
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7 | * you may not use this file except in compliance with the License. |
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8 | * You may obtain a copy of the License at |
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9 | * |
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10 | * http://www.apache.org/licenses/LICENSE-2.0 |
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11 | * |
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12 | * Unless required by applicable law or agreed to in writing, software |
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13 | * distributed under the License is distributed on an "AS IS" BASIS, |
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14 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
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15 | * See the License for the specific language governing permissions and |
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16 | * limitations under the License. |
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17 | */ |
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18 | ||
19 | import java.util.List; |
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20 | ||
21 | import org.apache.commons.logging.Log; |
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22 | import org.apache.commons.logging.LogFactory; |
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23 | ||
24 | import org.apache.ecs.ConcreteElement; |
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25 | ||
26 | import org.apache.turbine.Turbine; |
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27 | import org.apache.turbine.TurbineConstants; |
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28 | import org.apache.turbine.services.assemblerbroker.AssemblerBrokerService; |
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29 | import org.apache.turbine.services.assemblerbroker.TurbineAssemblerBroker; |
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30 | import org.apache.turbine.util.ObjectUtils; |
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31 | import org.apache.turbine.util.RunData; |
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32 | ||
33 | /** |
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34 | * The purpose of this class is to allow one to load and execute |
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35 | * Screen modules. |
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36 | * |
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37 | * @author <a href="mailto:mbryson@mont.mindspring.com">Dave Bryson</a> |
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38 | * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a> |
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39 | * @version $Id: ScreenLoader.java,v 1.10.2.3 2004/08/16 22:57:50 henning Exp $ |
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40 | */ |
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41 | public class ScreenLoader |
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42 | extends GenericLoader |
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43 | implements Loader |
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44 | { |
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45 | /** Logging */ |
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46 | 34 | private static Log log = LogFactory.getLog(ScreenLoader.class); |
47 | ||
48 | /** The single instance of this class. */ |
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49 | 17 | private static ScreenLoader instance = |
50 | new ScreenLoader(Turbine.getConfiguration() |
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51 | .getInt(TurbineConstants.SCREEN_CACHE_SIZE_KEY, |
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52 | TurbineConstants.SCREEN_CACHE_SIZE_DEFAULT)); |
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53 | ||
54 | /** The Assembler Broker Service */ |
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55 | 17 | private static AssemblerBrokerService ab = TurbineAssemblerBroker.getService(); |
56 | ||
57 | /** |
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58 | * These ctor's are private to force clients to use getInstance() |
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59 | * to access this class. |
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60 | */ |
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61 | private ScreenLoader() |
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62 | { |
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63 | 0 | super(); |
64 | 0 | } |
65 | ||
66 | /** |
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67 | * These ctor's are private to force clients to use getInstance() |
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68 | * to access this class. |
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69 | */ |
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70 | private ScreenLoader(int i) |
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71 | { |
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72 | 17 | super(i); |
73 | 17 | } |
74 | ||
75 | /** |
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76 | * Adds an instance of an object into the hashtable. |
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77 | * |
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78 | * @param name Name of object. |
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79 | * @param screen Screen to be associated with name. |
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80 | */ |
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81 | private void addInstance(String name, Screen screen) |
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82 | { |
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83 | 0 | if (cache()) |
84 | { |
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85 | 0 | this.put(name, (Screen) screen); |
86 | } |
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87 | 0 | } |
88 | ||
89 | /** |
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90 | * Attempts to load and execute the external Screen. This is used |
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91 | * when you want to execute a Screen which returns its output via |
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92 | * a MultiPartElement instead of out the data.getPage() value. |
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93 | * This allows you to easily chain the execution of Screen modules |
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94 | * together. |
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95 | * |
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96 | * @param data Turbine information. |
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97 | * @param name Name of object that will execute the screen. |
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98 | * @exception Exception a generic exception. |
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99 | */ |
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100 | public ConcreteElement eval(RunData data, String name) |
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101 | throws Exception |
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102 | { |
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103 | // Execute screen |
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104 | 0 | return getInstance(name).build(data); |
105 | } |
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106 | ||
107 | /** |
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108 | * Attempts to load and execute the Screen. This is used when you |
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109 | * want to execute a Screen which returns its output via the |
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110 | * data.getPage() object. |
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111 | * |
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112 | * @param data Turbine information. |
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113 | * @param name Name of object that will execute the screen. |
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114 | * @exception Exception a generic exception. |
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115 | */ |
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116 | public void exec(RunData data, String name) |
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117 | throws Exception |
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118 | { |
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119 | 0 | this.eval(data, name); |
120 | 0 | } |
121 | ||
122 | /** |
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123 | * Pulls out an instance of the object by name. Name is just the |
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124 | * single name of the object. This is equal to getInstance but |
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125 | * returns an Assembler object and is needed to fulfil the Loader |
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126 | * interface. |
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127 | * |
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128 | * @param name Name of object instance. |
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129 | * @return A Screen with the specified name, or null. |
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130 | * @exception Exception a generic exception. |
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131 | */ |
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132 | public Assembler getAssembler(String name) |
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133 | throws Exception |
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134 | { |
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135 | 23 | return getInstance(name); |
136 | } |
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137 | ||
138 | /** |
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139 | * Pulls out an instance of the Screen by name. Name is just the |
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140 | * single name of the Screen. |
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141 | * |
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142 | * @param name Name of requested Screen. |
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143 | * @return A Screen with the specified name, or null. |
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144 | * @exception Exception a generic exception. |
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145 | */ |
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146 | public Screen getInstance(String name) |
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147 | throws Exception |
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148 | { |
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149 | 23 | Screen screen = null; |
150 | ||
151 | // Check if the screen is already in the cache |
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152 | 23 | if (cache() && this.containsKey(name)) |
153 | { |
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154 | 0 | screen = (Screen) this.get(name); |
155 | 0 | log.debug("Found Screen " + name + " in the cache!"); |
156 | } |
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157 | else |
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158 | { |
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159 | 23 | log.debug("Loading Screen " + name + " from the Assembler Broker"); |
160 | ||
161 | try |
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162 | { |
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163 | 23 | if (ab != null) |
164 | { |
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165 | // Attempt to load the screen |
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166 | 23 | screen = (Screen) ab.getAssembler( |
167 | AssemblerBrokerService.SCREEN_TYPE, name); |
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168 | } |
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169 | } |
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170 | 0 | catch (ClassCastException cce) |
171 | { |
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172 | // This can alternatively let this exception be thrown |
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173 | // So that the ClassCastException is shown in the |
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174 | // browser window. Like this it shows "Screen not Found" |
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175 | 0 | screen = null; |
176 | 23 | } |
177 | ||
178 | 23 | if (screen == null) |
179 | { |
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180 | // If we did not find a screen we should try and give |
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181 | // the user a reason for that... |
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182 | // FIX ME: The AssemblerFactories should each add it's |
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183 | // own string here... |
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184 | 19 | List packages = Turbine.getConfiguration() |
185 | .getList(TurbineConstants.MODULE_PACKAGES); |
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186 | ||
187 | 19 | ObjectUtils.addOnce(packages, |
188 | GenericLoader.getBasePackage()); |
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189 | ||
190 | 19 | throw new ClassNotFoundException( |
191 | "\n\n\tRequested Screen not found: " + name + |
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192 | "\n\tTurbine looked in the following " + |
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193 | "modules.packages path: \n\t" + packages.toString() + "\n"); |
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194 | } |
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195 | 4 | else if (cache()) |
196 | { |
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197 | // The new instance is added to the cache |
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198 | 0 | addInstance(name, screen); |
199 | } |
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200 | } |
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201 | 4 | return screen; |
202 | } |
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203 | ||
204 | /** |
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205 | * The method through which this class is accessed. |
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206 | * |
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207 | * @return The single instance of this class. |
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208 | */ |
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209 | public static ScreenLoader getInstance() |
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210 | { |
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211 | 18 | return instance; |
212 | } |
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213 | } |
This report is generated by jcoverage, Maven and Maven JCoverage Plugin. |