Java tutorial
/* * Copyright (c) 1996, 2016, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. Oracle designates this * particular file as subject to the "Classpath" exception as provided * by Oracle in the LICENSE file that accompanied this code. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. */ /* * (C) Copyright Taligent, Inc. 1996, 1997 - All Rights Reserved * (C) Copyright IBM Corp. 1996 - 1998 - All Rights Reserved * * The original version of this source code and documentation * is copyrighted and owned by Taligent, Inc., a wholly-owned * subsidiary of IBM. These materials are provided under terms * of a License Agreement between Taligent and Sun. This technology * is protected by multiple US and International patents. * * This notice and attribution to Taligent may not be removed. * Taligent is a registered trademark of Taligent, Inc. */ package java.util; import java.io.InputStream; import java.io.InputStreamReader; import java.io.Reader; import java.io.IOException; import java.nio.charset.MalformedInputException; import java.nio.charset.StandardCharsets; import java.nio.charset.UnmappableCharacterException; import sun.security.action.GetPropertyAction; import sun.util.PropertyResourceBundleCharset; import sun.util.ResourceBundleEnumeration; /** * <code>PropertyResourceBundle</code> is a concrete subclass of * <code>ResourceBundle</code> that manages resources for a locale * using a set of static strings from a property file. See * {@link ResourceBundle ResourceBundle} for more information about resource * bundles. * * <p> * Unlike other types of resource bundle, you don't subclass * <code>PropertyResourceBundle</code>. Instead, you supply properties * files containing the resource data. <code>ResourceBundle.getBundle</code> * will automatically look for the appropriate properties file and create a * <code>PropertyResourceBundle</code> that refers to it. See * {@link ResourceBundle#getBundle(String, Locale, ClassLoader) ResourceBundle.getBundle} * for a complete description of the search and instantiation strategy. * * <p> * The following <a id="sample">example</a> shows a member of a resource * bundle family with the base name "MyResources". * The text defines the bundle "MyResources_de", * the German member of the bundle family. * This member is based on <code>PropertyResourceBundle</code>, and the text * therefore is the content of the file "MyResources_de.properties" * (a related <a href="ListResourceBundle.html#sample">example</a> shows * how you can add bundles to this family that are implemented as subclasses * of <code>ListResourceBundle</code>). * The keys in this example are of the form "s1" etc. The actual * keys are entirely up to your choice, so long as they are the same as * the keys you use in your program to retrieve the objects from the bundle. * Keys are case-sensitive. * <blockquote> * <pre> * # MessageFormat pattern * s1=Die Platte \"{1}\" enthält {0}. * * # location of {0} in pattern * s2=1 * * # sample disk name * s3=Meine Platte * * # first ChoiceFormat choice * s4=keine Dateien * * # second ChoiceFormat choice * s5=eine Datei * * # third ChoiceFormat choice * s6={0,number} Dateien * * # sample date * s7=3. März 1996 * </pre> * </blockquote> * * @apiNote * {@code PropertyResourceBundle} can be constructed either * from an {@code InputStream} or a {@code Reader}, which represents a property file. * Constructing a {@code PropertyResourceBundle} instance from an {@code InputStream} * requires that the input stream be encoded in {@code UTF-8}. By default, if a * {@link java.nio.charset.MalformedInputException} or an * {@link java.nio.charset.UnmappableCharacterException} occurs on reading the * input stream, then the {@code PropertyResourceBundle} instance resets to the state * before the exception, re-reads the input stream in {@code ISO-8859-1}, and * continues reading. If the system property * {@systemProperty java.util.PropertyResourceBundle.encoding} is set to either * "ISO-8859-1" or "UTF-8", the input stream is solely read in that encoding, * and throws the exception if it encounters an invalid sequence. * If "ISO-8859-1" is specified, characters that cannot be represented in * ISO-8859-1 encoding must be represented by Unicode Escapes as defined in section * 3.3 of <cite>The Java™ Language Specification</cite> * whereas the other constructor which takes a {@code Reader} does not have that limitation. * Other encoding values are ignored for this system property. * The system property is read and evaluated when initializing this class. * Changing or removing the property has no effect after the initialization. * * @implSpec * The implementation of a {@code PropertyResourceBundle} subclass must be * thread-safe if it's simultaneously used by multiple threads. The default * implementations of the non-abstract methods in this class are thread-safe. * * @see ResourceBundle * @see ListResourceBundle * @see Properties * @since 1.1 */ public class PropertyResourceBundle extends ResourceBundle { // Check whether the strict encoding is specified. // The possible encoding is either "ISO-8859-1" or "UTF-8". private static final String encoding = GetPropertyAction .privilegedGetProperty("java.util.PropertyResourceBundle.encoding", "").toUpperCase(Locale.ROOT); /** * Creates a property resource bundle from an {@link java.io.InputStream * InputStream}. This constructor reads the property file in UTF-8 by default. * If a {@link java.nio.charset.MalformedInputException} or an * {@link java.nio.charset.UnmappableCharacterException} occurs on reading the * input stream, then the PropertyResourceBundle instance resets to the state * before the exception, re-reads the input stream in {@code ISO-8859-1} and * continues reading. If the system property * {@code java.util.PropertyResourceBundle.encoding} is set to either * "ISO-8859-1" or "UTF-8", the input stream is solely read in that encoding, * and throws the exception if it encounters an invalid sequence. Other * encoding values are ignored for this system property. * The system property is read and evaluated when initializing this class. * Changing or removing the property has no effect after the initialization. * * @param stream an InputStream that represents a property file * to read from. * @throws IOException if an I/O error occurs * @throws NullPointerException if <code>stream</code> is null * @throws IllegalArgumentException if {@code stream} contains a * malformed Unicode escape sequence. * @throws MalformedInputException if the system property * {@code java.util.PropertyResourceBundle.encoding} is set to "UTF-8" * and {@code stream} contains an invalid UTF-8 byte sequence. * @throws UnmappableCharacterException if the system property * {@code java.util.PropertyResourceBundle.encoding} is set to "UTF-8" * and {@code stream} contains an unmappable UTF-8 byte sequence. */ @SuppressWarnings({ "unchecked", "rawtypes" }) public PropertyResourceBundle(InputStream stream) throws IOException { this(new InputStreamReader(stream, "ISO-8859-1".equals(encoding) ? StandardCharsets.ISO_8859_1.newDecoder() : new PropertyResourceBundleCharset("UTF-8".equals(encoding)).newDecoder())); } /** * Creates a property resource bundle from a {@link java.io.Reader * Reader}. Unlike the constructor * {@link #PropertyResourceBundle(java.io.InputStream) PropertyResourceBundle(InputStream)}, * there is no limitation as to the encoding of the input property file. * * @param reader a Reader that represents a property file to * read from. * @throws IOException if an I/O error occurs * @throws NullPointerException if <code>reader</code> is null * @throws IllegalArgumentException if a malformed Unicode escape sequence appears * from {@code reader}. * @since 1.6 */ @SuppressWarnings({ "unchecked", "rawtypes" }) public PropertyResourceBundle(Reader reader) throws IOException { Properties properties = new Properties(); properties.load(reader); lookup = new HashMap(properties); } // Implements java.util.ResourceBundle.handleGetObject; inherits javadoc specification. public Object handleGetObject(String key) { if (key == null) { throw new NullPointerException(); } return lookup.get(key); } /** * Returns an <code>Enumeration</code> of the keys contained in * this <code>ResourceBundle</code> and its parent bundles. * * @return an <code>Enumeration</code> of the keys contained in * this <code>ResourceBundle</code> and its parent bundles. * @see #keySet() */ public Enumeration<String> getKeys() { ResourceBundle parent = this.parent; return new ResourceBundleEnumeration(lookup.keySet(), (parent != null) ? parent.getKeys() : null); } /** * Returns a <code>Set</code> of the keys contained * <em>only</em> in this <code>ResourceBundle</code>. * * @return a <code>Set</code> of the keys contained only in this * <code>ResourceBundle</code> * @since 1.6 * @see #keySet() */ protected Set<String> handleKeySet() { return lookup.keySet(); } // ==================privates==================== private final Map<String, Object> lookup; }