Package java.util

Source Code of java.util.PropertyResourceBundle

/*
* @(#)PropertyResourceBundle.java  1.32 06/06/20
*
* Copyright 2006 Sun Microsystems, Inc. All rights reserved.
* SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
*/

/*
* (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.Reader;
import java.io.IOException;
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(java.lang.String, java.util.Locale, java.lang.ClassLoader) ResourceBundle.getBundle}
* for a complete description of the search and instantiation strategy.
*
* <p>
* The following <a name="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}\" enth&auml;lt {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. M&auml;rz 1996
* </pre>
* </blockquote>
*
* <p>
* <strong>Note:</strong> PropertyResourceBundle can be constructed either
* from an InputStream or a Reader, which represents a property file. 
* Constructing a PropertyResourceBundle instance from an InputStream requires
* that the input stream be encoded in ISO-8859-1.  In that case, characters
* that cannot be represented in ISO-8859-1 encoding must be represented by
* <a href="http://java.sun.com/docs/books/jls/third_edition/html/lexical.html#3.3">Unicode Escapes</a>,
* whereas the other constructor which takes a Reader does not have that limitation.
*
* @see ResourceBundle
* @see ListResourceBundle
* @see Properties
* @since JDK1.1
*/
public class PropertyResourceBundle extends ResourceBundle {
    /**
     * Creates a property resource bundle from an {@link java.io.InputStream
     * InputStream}.  The property file read with this constructor
     * must be encoded in ISO-8859-1.
     *
     * @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
     */
    public PropertyResourceBundle (InputStream stream) throws IOException {
        Properties properties = new Properties();
        properties.load(stream);
        lookup = new HashMap(properties);
    }

    /**
     * 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
     * @since 1.6
     */
    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 Map<String,Object> lookup;
}
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