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1 /* |
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2 * Copyright (c) 2008 Nokia Corporation and/or its subsidiary(-ies). |
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3 * All rights reserved. |
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4 * This component and the accompanying materials are made available |
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5 * under the terms of "Eclipse Public License v1.0" |
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6 * which accompanies this distribution, and is available |
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7 * at the URL "http://www.eclipse.org/legal/epl-v10.html". |
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8 * |
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9 * Initial Contributors: |
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10 * Nokia Corporation - initial contribution. |
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11 * |
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12 * Contributors: |
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13 * |
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14 * Description: |
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15 * |
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16 */ |
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17 |
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18 |
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19 package com.nokia.mj.impl.rt; |
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20 |
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21 import java.util.Hashtable; |
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22 import com.nokia.mj.impl.rt.support.SystemPropertyProvider; |
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23 import com.nokia.mj.impl.utils.Logger; |
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24 |
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25 /** |
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26 * A class that will be used to store system properties in CLDC VM. |
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27 * The class is inherited from Hashtable and there will be only one instance |
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28 * of it per VM instance. The VM will replace the original Hashtable with |
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29 * instace of this object which gives us the control when MIDlet is asking |
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30 * for any system property. Original system properties are in the private |
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31 * member and the parent hash table is used to store dynamic handlers. |
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32 * |
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33 * @author Nokia Corporation |
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34 * @version 1.0 |
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35 */ |
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36 |
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37 class SystemPropertyUtils |
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38 { |
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39 |
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40 private static final String |
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41 PROPERTY_HANDLER_CLASS_PREFIX = "com.nokia.mj.impl.properties."; |
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42 |
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43 /** |
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44 * Solves the possible dynamic property value. This a utility method |
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45 * to be called by VM dependent sytem properties extension mechanism. |
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46 * |
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47 * The utility will check if the value of the system property indicates |
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48 * that the method is dynamic. if it is not, then the value is returned |
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49 * directly, but if it is, then the value of the dynamic property will |
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50 * be solved by using defined property handler. |
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51 * |
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52 * @param propertyName the name of the system property. |
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53 * @param propertyValue the value of the system property. This must be |
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54 * passed as an argument even if the original |
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55 * Hashtable is also passed as third argument. |
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56 * That can't be used because calling the get method |
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57 * of the given Hashtable would lead to forever loop. |
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58 * @param props A hashtable containing the system properties. This is used |
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59 * to store the "freezed" system property value. |
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60 * @return value of the system property. |
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61 */ |
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62 public static Object solvePropertyValue(Object propertyName, |
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63 Object propertyValue, |
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64 Hashtable systemProperties) |
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65 { |
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66 // Check that the property name and the obtained value are strings |
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67 if (!(propertyName instanceof String) || |
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68 !(propertyValue instanceof String)) |
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69 { |
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70 // Not strings, return the non-string property value. |
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71 return propertyValue; |
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72 } |
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73 |
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74 String propertyNameStr = (String)propertyName; |
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75 String propertyValueStr = (String)propertyValue; |
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76 |
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77 try |
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78 { |
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79 // If the property value starts with ':' it is a dynamic property |
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80 if (propertyValueStr != null && propertyValueStr.length() > 0 && |
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81 propertyValueStr.charAt(0) == ':') |
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82 { |
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83 // Note for CDC. If some application wants to define some system |
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84 // property value that starts with ':' then it is needed to |
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85 // encode e.g. by using leading ':'. |
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86 if (propertyValueStr.length() > 1 && |
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87 propertyValueStr.charAt(1) == ':') |
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88 { |
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89 return propertyValueStr.substring(1); |
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90 } |
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91 |
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92 // Strip the dynamic property prefix away. |
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93 final String classEnding = propertyValueStr.substring(1); |
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94 // The result will be the end of the package and of |
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95 // the class name. |
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96 String className = PROPERTY_HANDLER_CLASS_PREFIX + |
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97 classEnding; |
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98 |
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99 try |
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100 { |
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101 Class clazz = clazz = Class.forName(className); |
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102 Object providerImpl = clazz.newInstance(); |
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103 |
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104 boolean isFrozen = false; |
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105 SystemPropertyProvider systemPropertyProvider = |
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106 (SystemPropertyProvider)providerImpl; |
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107 |
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108 propertyValueStr = |
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109 systemPropertyProvider.getProperty(propertyNameStr); |
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110 |
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111 isFrozen = |
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112 systemPropertyProvider.isStatic(propertyNameStr); |
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113 |
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114 // Freeze the value if the provider wants so |
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115 if (propertyValueStr != null && isFrozen) |
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116 { |
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117 systemProperties.put(propertyNameStr, |
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118 propertyValueStr); |
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119 } |
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120 return propertyValueStr; |
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121 } |
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122 catch (ClassNotFoundException e) |
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123 { |
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124 Logger.ELOG(Logger.EUtils, "Dynamic property handler " + |
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125 className + " was not found for " |
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126 + propertyName); |
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127 return ""; |
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128 } |
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129 |
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130 } |
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131 |
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132 // It wasn't dynamic, so returning the static value. |
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133 return propertyValueStr; |
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134 } |
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135 catch (Throwable t) |
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136 { |
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137 Logger.ELOG(Logger.EUtils, "Error in system properties: Key=" |
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138 + propertyNameStr + ", Val ='" + |
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139 propertyValueStr, t); |
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140 return ""; |
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141 } |
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142 } |
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143 } |
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144 |