Source for java.nio.charset.spi.CharsetProvider

   1: /* CharsetProvider.java -- charset service provider interface
   2:    Copyright (C) 2002, 2005, 2006 Free Software Foundation
   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., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 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: package java.nio.charset.spi;
  39: 
  40: import java.nio.charset.Charset;
  41: import java.util.Iterator;
  42: 
  43: 
  44: /**
  45:  * This class allows an implementor to provide additional character sets. The
  46:  * subclass must have a nullary constructor, and be attached to charset
  47:  * implementation classes. These extensions are loaded via the context class
  48:  * loader. To provide the charset extension, all files named
  49:  * <code>META-INF/services/java.nio.charset.spi.CharsetProvider</code> are
  50:  * read from the classpath. Each one should be a UTF-8 encoded list of
  51:  * fully-qualified names of concrete subclasses of this class; whitespace is
  52:  * ignored, and '#' starts comments. Duplicates are ignored. The
  53:  * implementations must be accessible to the classloader that requests them.
  54:  *
  55:  * @author Eric Blake (ebb9@email.byu.edu)
  56:  * @see Charset
  57:  * @since 1.4
  58:  * @status updated to 1.4
  59:  */
  60: public abstract class CharsetProvider
  61: {
  62:   /**
  63:    * Initialize a new charset provider. This performs a security check on
  64:    * RuntimePermission("charsetProvider").
  65:    *
  66:    * @throws SecurityException if building a new set is not allowed
  67:    */
  68:   protected CharsetProvider()
  69:   {
  70:     // We only do the security check for custom providers, not for the
  71:     // built in ones.
  72:     SecurityManager s = System.getSecurityManager();
  73:     if (s != null &&
  74:         ! (this instanceof gnu.java.nio.charset.Provider
  75:         || this instanceof gnu.java.nio.charset.iconv.IconvProvider))
  76:       s.checkPermission(new RuntimePermission("charsetProvider"));
  77:   }
  78: 
  79:   /**
  80:    * Returns an iterator over the charsets defined by this provider.
  81:    *
  82:    * @return the iterator
  83:    * @see Charset#availableCharsets()
  84:    */
  85:   public abstract Iterator<Charset> charsets();
  86: 
  87:   /**
  88:    * Returns the named charset, by canonical name or alias.
  89:    *
  90:    * @param name the name of the character
  91:    *
  92:    * @return the charset, or null if not supported
  93:    */
  94:   public abstract Charset charsetForName(String name);
  95: } // class CharsetProvider