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org.apache.turbine.modules.NavigationLoader |
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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 | * Navigation 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: NavigationLoader.java 264148 2005-08-29 14:21:04Z henning $ |
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40 | */ |
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41 | 21 | public class NavigationLoader |
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 = 5062299200802529612L; |
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47 | ||
48 | /** Logging */ |
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49 | 84 | private static Log log = LogFactory.getLog(NavigationLoader.class); |
50 | ||
51 | /** The single instance of this class. */ |
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52 | 42 | private static NavigationLoader instance = |
53 | new NavigationLoader(Turbine.getConfiguration() |
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54 | .getInt(TurbineConstants.NAVIGATION_CACHE_SIZE_KEY, |
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55 | TurbineConstants.NAVIGATION_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 NavigationLoader() |
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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 NavigationLoader(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 navigation Navigation to be associated with name. |
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83 | */ |
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84 | private void addInstance(String name, Navigation navigation) |
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85 | { |
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86 | 0 | if (cache()) |
87 | { |
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88 | 0 | this.put(name, (Navigation) navigation); |
89 | } |
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90 | 0 | } |
91 | ||
92 | /** |
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93 | * Attempts to load and execute the external Navigation. This is |
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94 | * used when you want to execute a Navigation which returns its |
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95 | * output via a MultiPartElement instead of out the data.getPage() |
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96 | * value. This allows you to easily chain the execution of |
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97 | * Navigation modules 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 navigation. |
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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 Navigation |
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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 external Navigation. |
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112 | * |
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113 | * @param data Turbine information. |
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114 | * @param name Name of object instance. |
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115 | * @exception Exception a generic exception. |
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116 | */ |
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117 | public void exec(RunData data, String name) |
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118 | throws Exception |
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119 | { |
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120 | 0 | this.eval(data, name); |
121 | 0 | } |
122 | ||
123 | /** |
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124 | * Pulls out an instance of the object by name. Name is just the |
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125 | * single name of the object. This is equal to getInstance but |
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126 | * returns an Assembler object and is needed to fulfil the Loader |
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127 | * interface. |
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128 | * |
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129 | * @param name Name of object instance. |
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130 | * @return A Layout with the specified name, or null. |
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131 | * @exception Exception a generic exception. |
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132 | */ |
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133 | public Assembler getAssembler(String name) |
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134 | throws Exception |
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135 | { |
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136 | 46 | return getInstance(name); |
137 | } |
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138 | ||
139 | /** |
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140 | * Pulls out an instance of the Navigation by name. Name is just the |
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141 | * single name of the Navigation. |
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142 | * |
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143 | * @param name Name of requested Navigation |
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144 | * @return A Navigation with the specified name, or null. |
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145 | * @exception Exception a generic exception. |
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146 | */ |
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147 | public Navigation getInstance(String name) |
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148 | throws Exception |
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149 | { |
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150 | 46 | Navigation navigation = null; |
151 | ||
152 | // Check if the navigation is already in the cache |
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153 | 46 | if (cache() && this.containsKey(name)) |
154 | { |
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155 | 0 | navigation = (Navigation) this.get(name); |
156 | 0 | log.debug("Found Navigation " + name + " in the cache!"); |
157 | } |
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158 | else |
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159 | { |
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160 | 46 | log.debug("Loading Navigation " + name + " from the Assembler Broker"); |
161 | ||
162 | try |
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163 | { |
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164 | 46 | if (ab != null) |
165 | { |
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166 | // Attempt to load the navigation |
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167 | 46 | navigation = (Navigation) ab.getAssembler( |
168 | AssemblerBrokerService.NAVIGATION_TYPE, name); |
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169 | } |
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170 | 23 | } |
171 | 0 | catch (ClassCastException cce) |
172 | { |
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173 | // This can alternatively let this exception be thrown |
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174 | // So that the ClassCastException is shown in the |
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175 | // browser window. Like this it shows "Screen not Found" |
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176 | 0 | navigation = null; |
177 | 23 | } |
178 | ||
179 | 46 | if (navigation == null) |
180 | { |
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181 | // If we did not find a screen we should try and give |
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182 | // the user a reason for that... |
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183 | // FIX ME: The AssemblerFactories should each add it's |
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184 | // own string here... |
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185 | 38 | List packages = Turbine.getConfiguration() |
186 | .getList(TurbineConstants.MODULE_PACKAGES); |
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187 | ||
188 | 38 | ObjectUtils.addOnce(packages, |
189 | GenericLoader.getBasePackage()); |
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190 | ||
191 | 38 | throw new ClassNotFoundException( |
192 | "\n\n\tRequested Navigation not found: " + name + |
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193 | "\n\tTurbine looked in the following " + |
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194 | "modules.packages path: \n\t" + packages.toString() + "\n"); |
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195 | } |
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196 | 8 | else if (cache()) |
197 | { |
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198 | // The new instance is added to the cache |
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199 | 0 | addInstance(name, navigation); |
200 | } |
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201 | } |
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202 | 8 | return navigation; |
203 | } |
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204 | ||
205 | /** |
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206 | * The method through which this class is accessed. |
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207 | * |
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208 | * @return The single instance of this class. |
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209 | */ |
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210 | public static NavigationLoader getInstance() |
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211 | { |
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212 | 44 | return instance; |
213 | } |
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214 | } |
This report is generated by jcoverage, Maven and Maven JCoverage Plugin. |