libjava/java/util/PropertyResourceBundle.java

   1 /* PropertyResourceBundle -- a resource bundle built from a Property file
   2    Copyright (C) 1998, 1999, 2001, 2002 Free Software Foundation, Inc.
   3
   4 This file is part of GNU Classpath.
   5
   6 GNU Classpath is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 GNU Classpath is distributed in the hope that it will be useful, but
  12 WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14 General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU Classpath; see the file COPYING.  If not, write to the
  18 Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 USA.
  20
  21 Linking this library statically or dynamically with other modules is
  22 making a combined work based on this library.  Thus, the terms and
  23 conditions of the GNU General Public License cover the whole
  24 combination.
  25
  26 As a special exception, the copyright holders of this library give you
  27 permission to link this library with independent modules to produce an
  28 executable, regardless of the license terms of these independent
  29 modules, and to copy and distribute the resulting executable under
  30 terms of your choice, provided that you also meet, for each linked
  31 independent module, the terms and conditions of the license of that
  32 module.  An independent module is a module which is not derived from
  33 or based on this library.  If you modify this library, you may extend
  34 this exception to your version of the library, but you are not
  35 obligated to do so.  If you do not wish to do so, delete this
  36 exception statement from your version. */
  37
  38
  39 package java.util;
  40
  41 import java.io.IOException;
  42 import java.io.InputStream;
  43
  44 /**
  45  * This class is a concrete <code>ResourceBundle</code> that gets it
  46  * resources from a property file. This implies that the resources are
  47  * strings. For more information about resource bundles see the class
  48  * <code>ResourceBundle</code>.
  49  *
  50  * You should not use this class directly, or subclass it, but you get
  51  * an object of this class automatically when you call
  52  * <code>ResourceBundle.getBundle()</code> and there is a properties
  53  * file.
  54  *
  55  * If there is also a class for this resource and the same locale, the
  56  * class will be chosen. The properties file should have the name of the
  57  * resource bundle, appended with the locale (e.g. <code>_de</code) and the
  58  * extension <code>.properties</code>. The file should have the same format
  59  * as for <code>Properties.load()</code>
  60  *
  61  * An example of a properties file for the german language is given
  62  * here. This extends the example given in ListResourceBundle.
  63  * Create a file MyResource_de.properties with the following contents
  64  * and put it in the CLASSPATH. (The char <code>\u00e4</code> is the
  65  * german umlaut)
  66  *
  67  *
  68 <pre>
  69 s1=3
  70 s2=MeineDisk
  71 s3=3. M\u00e4rz 96
  72 s4=Die Diskette ''{1}'' enth\u00e4lt {0} in {2}.
  73 s5=0
  74 s6=keine Dateien
  75 s7=1
  76 s8=eine Datei
  77 s9=2
  78 s10={0,number} Dateien
  79 s11=Die Formatierung warf eine Exception: {0}
  80 s12=FEHLER
  81 s13=Ergebnis
  82 s14=Dialog
  83 s15=Auswahlkriterium
  84 s16=1,3
  85 </pre>
  86  *
  87  * @author Jochen Hoenicke
  88  * @see ResourceBundle
  89  * @see ListResourceBundle
  90  * @see Properties#load()
  91  * @since 1.1
  92  * @status updated to 1.4
  93  */
  94 public class PropertyResourceBundle extends ResourceBundle
  95 {
  96   /** The properties file this bundle is based on. */
  97   private Properties properties;
  98
  99   /**
 100    * Creates a new property resource bundle.
 101    *
 102    * @param stream an input stream, where the resources are read from
 103    * @throws NullPointerException if stream is null
 104    * @throws IOException if reading the stream fails
 105    */
 106   public PropertyResourceBundle(InputStream stream) throws IOException
 107   {
 108     properties = new Properties();
 109     properties.load(stream);
 110   }
 111
 112   /**
 113    * Called by <code>getObject</code> when a resource is needed. This
 114    * returns the resource given by the key.
 115    *
 116    * @param key the key of the resource
 117    * @return the resource for the key, or null if it doesn't exist
 118    */
 119   public Object handleGetObject(String key)
 120   {
 121     return properties.getProperty(key);
 122   }
 123
 124   /**
 125    * This method should return all keys for which a resource exists.
 126    *
 127    * @return an enumeration of the keys
 128    */
 129   public Enumeration getKeys()
 130   {
 131     if (parent == null)
 132       return properties.propertyNames();
 133     // We make a new Set that holds all the keys, then return an enumeration
 134     // for that. This prevents modifications from ruining the enumeration,
 135     // as well as ignoring duplicates.
 136     Set s = new HashSet();
 137     Enumeration e = properties.propertyNames();
 138     while (e.hasMoreElements())
 139       s.add(e.nextElement());
 140     ResourceBundle bundle = parent;
 141     // Eliminate tail recursion.
 142     do
 143       {
 144         e = bundle.getKeys();
 145         while (e.hasMoreElements())
 146           s.add(e.nextElement());
 147         bundle = bundle.parent;
 148       }
 149     while (bundle != null);
 150     return Collections.enumeration(s);
 151   }
 152 } // class PropertyResourceBundle