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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 2001-2005 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 264148 2005-08-29 14:21:04Z henning $ |
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40 | */ |
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41 | 21 | public class ScreenLoader |
42 | extends GenericLoader |
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43 | implements Loader |
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44 | { |
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45 | /** Serial Version UID */ |
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46 | private static final long serialVersionUID = -4825216334500657398L; |
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47 | ||
48 | /** Logging */ |
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49 | 84 | private static Log log = LogFactory.getLog(ScreenLoader.class); |
50 | ||
51 | /** The single instance of this class. */ |
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52 | 42 | private static ScreenLoader instance = |
53 | new ScreenLoader(Turbine.getConfiguration() |
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54 | .getInt(TurbineConstants.SCREEN_CACHE_SIZE_KEY, |
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55 | TurbineConstants.SCREEN_CACHE_SIZE_DEFAULT)); |
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56 | ||
57 | /** The Assembler Broker Service */ |
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58 | 42 | private static AssemblerBrokerService ab = TurbineAssemblerBroker.getService(); |
59 | ||
60 | /** |
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61 | * These ctor's are private to force clients to use getInstance() |
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62 | * to access this class. |
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63 | */ |
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64 | private ScreenLoader() |
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65 | { |
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66 | 0 | super(); |
67 | 0 | } |
68 | ||
69 | /** |
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70 | * These ctor's are private to force clients to use getInstance() |
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71 | * to access this class. |
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72 | */ |
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73 | private ScreenLoader(int i) |
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74 | { |
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75 | 42 | super(i); |
76 | 42 | } |
77 | ||
78 | /** |
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79 | * Adds an instance of an object into the hashtable. |
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80 | * |
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81 | * @param name Name of object. |
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82 | * @param screen Screen to be associated with name. |
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83 | */ |
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84 | private void addInstance(String name, Screen screen) |
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85 | { |
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86 | 0 | if (cache()) |
87 | { |
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88 | 0 | this.put(name, (Screen) screen); |
89 | } |
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90 | 0 | } |
91 | ||
92 | /** |
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93 | * Attempts to load and execute the external Screen. This is used |
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94 | * when you want to execute a Screen which returns its output via |
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95 | * a MultiPartElement instead of out the data.getPage() value. |
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96 | * This allows you to easily chain the execution of Screen modules |
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97 | * together. |
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98 | * |
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99 | * @param data Turbine information. |
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100 | * @param name Name of object that will execute the screen. |
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101 | * @exception Exception a generic exception. |
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102 | */ |
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103 | public ConcreteElement eval(RunData data, String name) |
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104 | throws Exception |
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105 | { |
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106 | // Execute screen |
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107 | 0 | return getInstance(name).build(data); |
108 | } |
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109 | ||
110 | /** |
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111 | * Attempts to load and execute the Screen. This is used when you |
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112 | * want to execute a Screen which returns its output via the |
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113 | * data.getPage() object. |
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114 | * |
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115 | * @param data Turbine information. |
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116 | * @param name Name of object that will execute the screen. |
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117 | * @exception Exception a generic exception. |
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118 | */ |
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119 | public void exec(RunData data, String name) |
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120 | throws Exception |
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121 | { |
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122 | 0 | this.eval(data, name); |
123 | 0 | } |
124 | ||
125 | /** |
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126 | * Pulls out an instance of the object by name. Name is just the |
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127 | * single name of the object. This is equal to getInstance but |
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128 | * returns an Assembler object and is needed to fulfil the Loader |
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129 | * interface. |
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130 | * |
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131 | * @param name Name of object instance. |
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132 | * @return A Screen with the specified name, or null. |
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133 | * @exception Exception a generic exception. |
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134 | */ |
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135 | public Assembler getAssembler(String name) |
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136 | throws Exception |
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137 | { |
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138 | 46 | return getInstance(name); |
139 | } |
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140 | ||
141 | /** |
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142 | * Pulls out an instance of the Screen by name. Name is just the |
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143 | * single name of the Screen. |
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144 | * |
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145 | * @param name Name of requested Screen. |
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146 | * @return A Screen with the specified name, or null. |
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147 | * @exception Exception a generic exception. |
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148 | */ |
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149 | public Screen getInstance(String name) |
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150 | throws Exception |
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151 | { |
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152 | 46 | Screen screen = null; |
153 | ||
154 | // Check if the screen is already in the cache |
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155 | 46 | if (cache() && this.containsKey(name)) |
156 | { |
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157 | 0 | screen = (Screen) this.get(name); |
158 | 0 | log.debug("Found Screen " + name + " in the cache!"); |
159 | } |
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160 | else |
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161 | { |
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162 | 46 | log.debug("Loading Screen " + name + " from the Assembler Broker"); |
163 | ||
164 | try |
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165 | { |
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166 | 46 | if (ab != null) |
167 | { |
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168 | // Attempt to load the screen |
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169 | 46 | screen = (Screen) ab.getAssembler( |
170 | AssemblerBrokerService.SCREEN_TYPE, name); |
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171 | } |
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172 | 23 | } |
173 | 0 | catch (ClassCastException cce) |
174 | { |
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175 | // This can alternatively let this exception be thrown |
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176 | // So that the ClassCastException is shown in the |
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177 | // browser window. Like this it shows "Screen not Found" |
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178 | 0 | screen = null; |
179 | 23 | } |
180 | ||
181 | 46 | if (screen == null) |
182 | { |
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183 | // If we did not find a screen we should try and give |
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184 | // the user a reason for that... |
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185 | // FIX ME: The AssemblerFactories should each add it's |
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186 | // own string here... |
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187 | 38 | List packages = Turbine.getConfiguration() |
188 | .getList(TurbineConstants.MODULE_PACKAGES); |
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189 | ||
190 | 38 | ObjectUtils.addOnce(packages, |
191 | GenericLoader.getBasePackage()); |
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192 | ||
193 | 38 | throw new ClassNotFoundException( |
194 | "\n\n\tRequested Screen not found: " + name + |
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195 | "\n\tTurbine looked in the following " + |
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196 | "modules.packages path: \n\t" + packages.toString() + "\n"); |
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197 | } |
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198 | 8 | else if (cache()) |
199 | { |
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200 | // The new instance is added to the cache |
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201 | 0 | addInstance(name, screen); |
202 | } |
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203 | } |
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204 | 8 | return screen; |
205 | } |
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206 | ||
207 | /** |
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208 | * The method through which this class is accessed. |
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209 | * |
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210 | * @return The single instance of this class. |
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211 | */ |
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212 | public static ScreenLoader getInstance() |
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213 | { |
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214 | 44 | return instance; |
215 | } |
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216 | } |
This report is generated by jcoverage, Maven and Maven JCoverage Plugin. |