code.grnet.gr Git - pithos/blob - src/gr/ebs/gss/server/configuration/GSSConfigurationFactory.java

   1 /*\r
   2  * Copyright 2006, 2007, 2008, 2009 Electronic Business Systems Ltd.\r
   3  *\r
   4  * This file is part of GSS.\r
   5  *\r
   6  * GSS is free software: you can redistribute it and/or modify\r
   7  * it under the terms of the GNU General Public License as published by\r
   8  * the Free Software Foundation, either version 3 of the License, or\r
   9  * (at your option) any later version.\r
  10  *\r
  11  * GSS is distributed in the hope that it will be useful,\r
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of\r
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the\r
  14  * GNU General Public License for more details.\r
  15  *\r
  16  * You should have received a copy of the GNU General Public License\r
  17  * along with GSS.  If not, see <http://www.gnu.org/licenses/>.\r
  18  */\r
  19 package gr.ebs.gss.server.configuration;\r
  20 \r
  21 import java.io.File;\r
  22 import java.net.MalformedURLException;\r
  23 import java.net.URL;\r
  24 \r
  25 import org.apache.commons.configuration.BaseConfiguration;\r
  26 import org.apache.commons.configuration.ConfigurationException;\r
  27 import org.apache.commons.configuration.ConfigurationUtils;\r
  28 import org.apache.commons.configuration.DataConfiguration;\r
  29 import org.apache.commons.configuration.PropertiesConfiguration;\r
  30 import org.apache.commons.configuration.reloading.FileChangedReloadingStrategy;\r
  31 import org.apache.commons.logging.Log;\r
  32 import org.apache.commons.logging.LogFactory;\r
  33 \r
  34 /**\r
  35  * Singleton that loads properties from gss.properties and\r
  36  * makes them available to all\r
  37  *\r
  38  * @author droutsis\r
  39  */\r
  40 public final class GSSConfigurationFactory {\r
  41 \r
  42         /**\r
  43          * The logger.\r
  44          */\r
  45         private static Log logger = LogFactory.getLog(GSSConfigurationFactory.class);\r
  46 \r
  47         /**\r
  48          * The filename of the file containing system properties.\r
  49          */\r
  50         private static String configFilename = "gss.properties";\r
  51 \r
  52         /**\r
  53          * The (single) configuration object\r
  54          */\r
  55         private static DataConfiguration configuration = null;\r
  56 \r
  57         /**\r
  58          * Exists only to defeat instantiation.\r
  59          */\r
  60         private GSSConfigurationFactory() {\r
  61         }\r
  62 \r
  63         /**\r
  64          * Because multiple classloaders are commonly used in many situations -\r
  65          * including servlet containers - you can wind up with multiple singleton instances\r
  66          * no matter how carefully you've implemented your singleton classes.\r
  67          * If you want to make sure the same classloader loads your singletons,\r
  68          * you must specify the classloader yourself; for example:\r
  69          *\r
  70          * @param classname\r
  71          * @return\r
  72          * @throws ClassNotFoundException\r
  73          */\r
  74         private static Class getClass(String classname) throws ClassNotFoundException {\r
  75               ClassLoader classLoader = Thread.currentThread().getContextClassLoader();\r
  76               if(classLoader == null)\r
  77                  classLoader = GSSConfigurationFactory.class.getClassLoader();\r
  78               return classLoader.loadClass(classname);\r
  79         }\r
  80 \r
  81         /**\r
  82          * @return the configuration object\r
  83          */\r
  84         public synchronized static DataConfiguration getConfiguration() {\r
  85                 try {\r
  86                         if (configuration==null) {\r
  87                                 PropertiesConfiguration gssConfig = (PropertiesConfiguration) getClass(PropertiesConfiguration.class.getCanonicalName()).newInstance();\r
  88                                 gssConfig.setBasePath("");\r
  89                                 gssConfig.setFileName(configFilename);\r
  90                                 gssConfig.setEncoding("ISO-8859-7");\r
  91                                 // Set automatic reloading.\r
  92                                 gssConfig.setReloadingStrategy(new VfsFileChangedReloadingStrategy());\r
  93                                 gssConfig.load();\r
  94                                 // Decorator.\r
  95                                 configuration = new DataConfiguration(gssConfig);\r
  96                         }\r
  97                         return configuration;\r
  98                 }\r
  99                 catch (ClassNotFoundException e) {\r
 100                         // Use empty configuration, so we get no NPE but default values\r
 101                         configuration = new DataConfiguration(new BaseConfiguration());\r
 102                         logger.error("Error in ExternalAPI initialization! GSS is running with default values!", e);\r
 103                         return configuration;\r
 104                 } catch (InstantiationException e) {\r
 105                         // Use empty configuration, so we get no NPE but default values\r
 106                         configuration = new DataConfiguration(new BaseConfiguration());\r
 107                         logger.error("Error in ExternalAPI initialization! GSS is running with default values!", e);\r
 108                         return configuration;\r
 109                 } catch (IllegalAccessException e) {\r
 110                         // Use empty configuration, so we get no NPE but default values\r
 111                         configuration = new DataConfiguration(new BaseConfiguration());\r
 112                         logger.error("Error in ExternalAPI initialization! GSS is running with default values!", e);\r
 113                         return configuration;\r
 114                 } catch (ConfigurationException e) {\r
 115                         // Use empty configuration, so we get no NPE but default values\r
 116                         configuration = new DataConfiguration(new BaseConfiguration());\r
 117                         logger.error("Error in ExternalAPI initialization! GSS is running with default values!", e);\r
 118                         return configuration;\r
 119                 }\r
 120         }\r
 121 \r
 122         /**\r
 123          * Extends the FileChangedReloadingStrategy from Commons Configuration, adding\r
 124          * support for files in JBoss MC VFS.\r
 125          *\r
 126          * @author past\r
 127          */\r
 128         private static class VfsFileChangedReloadingStrategy extends FileChangedReloadingStrategy {\r
 129             /** Constant for the jar URL protocol.*/\r
 130             private static final String JAR_PROTOCOL = "jar";\r
 131             /** Constant for the JBoss MC VFSFile URL protocol.*/\r
 132             private static final String VFSFILE_PROTOCOL = "vfsfile";\r
 133 \r
 134             @Override\r
 135                 protected File getFile()\r
 136             {\r
 137                 return configuration.getURL() != null ? fileFromURL(configuration\r
 138                         .getURL()) : configuration.getFile();\r
 139             }\r
 140 \r
 141             /**\r
 142              * Helper method for transforming a URL into a file object. This method\r
 143              * handles file: and jar: URLs, as well as JBoss VFS-specific vfsfile:\r
 144              * URLs.\r
 145              *\r
 146              * @param url the URL to be converted\r
 147              * @return the resulting file or <b>null </b>\r
 148              */\r
 149             private File fileFromURL(URL url)\r
 150             {\r
 151                 if (VFSFILE_PROTOCOL.equals(url.getProtocol()))\r
 152                 {\r
 153                     String path = url.getPath();\r
 154                     try\r
 155                     {\r
 156                         return ConfigurationUtils.fileFromURL(new URL("file:" + path));\r
 157                     }\r
 158                     catch (MalformedURLException mex)\r
 159                     {\r
 160                         return null;\r
 161                     }\r
 162                 }\r
 163                 else if (JAR_PROTOCOL.equals(url.getProtocol()))\r
 164                 {\r
 165                     String path = url.getPath();\r
 166                     try\r
 167                     {\r
 168                         return ConfigurationUtils.fileFromURL(new URL(path.substring(0,\r
 169                                 path.indexOf('!'))));\r
 170                     }\r
 171                     catch (MalformedURLException mex)\r
 172                     {\r
 173                         return null;\r
 174                     }\r
 175                 } else\r
 176                                 return ConfigurationUtils.fileFromURL(url);\r
 177             }\r
 178         }\r
 179 }\r