116 lines
4.6 KiB
Java
116 lines
4.6 KiB
Java
/*
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* Copyright (c) 2000, 2013, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation. Oracle designates this
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* particular file as subject to the "Classpath" exception as provided
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* by Oracle in the LICENSE file that accompanied this code.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*/
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package java.nio.charset.spi;
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import java.nio.charset.Charset;
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import java.util.Iterator;
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/**
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* Charset service-provider class.
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*
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* <p> A charset provider is a concrete subclass of this class that has a
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* zero-argument constructor and some number of associated charset
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* implementation classes. Charset providers may be installed in an instance
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* of the Java platform as extensions. Providers may also be made available by
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* adding them to the applet or application class path or by some other
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* platform-specific means. Charset providers are looked up via the current
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* thread's {@link java.lang.Thread#getContextClassLoader() context class
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* loader}.
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*
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* <p> A charset provider identifies itself with a provider-configuration file
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* named {@code java.nio.charset.spi.CharsetProvider} in the resource
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* directory {@code META-INF/services}. The file should contain a list of
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* fully-qualified concrete charset-provider class names, one per line. A line
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* is terminated by any one of a line feed ({@code '\n'}), a carriage return
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* ({@code '\r'}), or a carriage return followed immediately by a line feed.
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* Space and tab characters surrounding each name, as well as blank lines, are
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* ignored. The comment character is {@code '#'} (<code>'\u0023'</code>); on
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* each line all characters following the first comment character are ignored.
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* The file must be encoded in UTF-8.
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*
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* <p> If a particular concrete charset provider class is named in more than
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* one configuration file, or is named in the same configuration file more than
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* once, then the duplicates will be ignored. The configuration file naming a
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* particular provider need not be in the same jar file or other distribution
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* unit as the provider itself. The provider must be accessible from the same
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* class loader that was initially queried to locate the configuration file;
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* this is not necessarily the class loader that loaded the file. </p>
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*
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*
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* @author Mark Reinhold
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* @author JSR-51 Expert Group
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* @since 1.4
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*
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* @see java.nio.charset.Charset
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*/
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public abstract class CharsetProvider {
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private static Void checkPermission() {
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SecurityManager sm = System.getSecurityManager();
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if (sm != null)
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sm.checkPermission(new RuntimePermission("charsetProvider"));
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return null;
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}
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private CharsetProvider(Void ignore) { }
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/**
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* Initializes a new charset provider.
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*
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* @throws SecurityException
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* If a security manager has been installed and it denies
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* {@link RuntimePermission}{@code ("charsetProvider")}
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*/
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protected CharsetProvider() {
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this(checkPermission());
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}
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/**
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* Creates an iterator that iterates over the charsets supported by this
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* provider. This method is used in the implementation of the {@link
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* java.nio.charset.Charset#availableCharsets Charset.availableCharsets}
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* method.
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*
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* @return The new iterator
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*/
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public abstract Iterator<Charset> charsets();
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/**
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* Retrieves a charset for the given charset name.
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*
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* @param charsetName
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* The name of the requested charset; may be either
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* a canonical name or an alias
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*
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* @return A charset object for the named charset,
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* or {@code null} if the named charset
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* is not supported by this provider
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*/
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public abstract Charset charsetForName(String charsetName);
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}
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