001 /* CharsetProvider.java -- charset service provider interface
002 Copyright (C) 2002, 2006, 2007 Free Software Foundation
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038 package java.nio.charset.spi;
039
040 import java.nio.charset.Charset;
041 import java.util.Iterator;
042
043
044 /**
045 * This class allows an implementor to provide additional character sets. The
046 * subclass must have a nullary constructor, and be attached to charset
047 * implementation classes. These extensions are loaded via the context class
048 * loader. To provide the charset extension, all files named
049 * <code>META-INF/services/java.nio.charset.spi.CharsetProvider</code> are
050 * read from the classpath. Each one should be a UTF-8 encoded list of
051 * fully-qualified names of concrete subclasses of this class; whitespace is
052 * ignored, and '#' starts comments. Duplicates are ignored. The
053 * implementations must be accessible to the classloader that requests them.
054 *
055 * @author Eric Blake (ebb9@email.byu.edu)
056 * @see Charset
057 * @since 1.4
058 * @status updated to 1.4
059 */
060 public abstract class CharsetProvider
061 {
062 /**
063 * Initialize a new charset provider. This performs a security check on
064 * RuntimePermission("charsetProvider").
065 *
066 * @throws SecurityException if building a new set is not allowed
067 */
068 protected CharsetProvider()
069 {
070 // We only do the security check for custom providers, not for the
071 // built in ones.
072 SecurityManager s = System.getSecurityManager();
073 if (s != null &&
074 ! (this instanceof gnu.java.nio.charset.Provider))
075 // GCJ LOCAL - We have the iconv provider in standard.omit
076 // || this instanceof gnu.java.nio.charset.iconv.IconvProvider))
077 s.checkPermission(new RuntimePermission("charsetProvider"));
078 }
079
080 /**
081 * Returns an iterator over the charsets defined by this provider.
082 *
083 * @return the iterator
084 * @see Charset#availableCharsets()
085 */
086 public abstract Iterator<Charset> charsets();
087
088 /**
089 * Returns the named charset, by canonical name or alias.
090 *
091 * @param name the name of the character
092 *
093 * @return the charset, or null if not supported
094 */
095 public abstract Charset charsetForName(String name);
096 } // class CharsetProvider