toolchain/gcc/libjava/java/nio/channels/spi/SelectorProvider.java

   1 /* SelectorProvider.java
   2    Copyright (C) 2002, 2003 Free Software Foundation, Inc.
   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., 59 Temple Place, Suite 330, Boston, MA
  19 02111-1307 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.channels.spi;
  39
  40 import gnu.java.nio.SelectorProviderImpl;
  41 import java.io.IOException;
  42 import java.nio.channels.DatagramChannel;
  43 import java.nio.channels.Pipe;
  44 import java.nio.channels.ServerSocketChannel;
  45 import java.nio.channels.SocketChannel;
  46
  47 /**
  48  * @author Michael Koch
  49  * @since 1.4
  50  */
  51 public abstract class SelectorProvider
  52 {
  53   private static SelectorProvider systemDefaultProvider;
  54
  55   /**
  56    * Initializes the selector provider.
  57    *
  58    * @exception SecurityException If a security manager has been installed and
  59    * it denies @see RuntimePermission ("selectorProvider").
  60    */
  61   protected SelectorProvider ()
  62   {
  63     SecurityManager sm = System.getSecurityManager ();
  64     if (sm != null)
  65       sm.checkPermission (new RuntimePermission ("selectorProvider"));
  66   }
  67
  68   /**
  69    * Opens a datagram channel.
  70    */
  71   public abstract DatagramChannel openDatagramChannel () throws IOException;
  72
  73   /**
  74    * Opens a pipe.
  75    */
  76   public abstract Pipe openPipe () throws IOException;
  77
  78   /**
  79    * Opens a selector.
  80    */
  81   public abstract AbstractSelector openSelector () throws IOException;
  82
  83   /**
  84    * Opens a server socket channel.
  85    */
  86   public abstract ServerSocketChannel openServerSocketChannel ()
  87     throws IOException;
  88
  89   /**
  90    * Opens a socket channel.
  91    */
  92   public abstract SocketChannel openSocketChannel () throws IOException;
  93
  94   /**
  95    * Returns the system-wide default selector provider for this invocation
  96    * of the Java virtual machine.
  97    */
  98   public static synchronized SelectorProvider provider ()
  99   {
 100     if (systemDefaultProvider == null)
 101       {
 102         String propertyValue =
 103           System.getProperty ("java.nio.channels.spi.SelectorProvider");
 104
 105         if (propertyValue == null
 106             || propertyValue.equals (""))
 107           systemDefaultProvider = new SelectorProviderImpl();
 108         else
 109           {
 110             try
 111               {
 112                 systemDefaultProvider = (SelectorProvider) Class.forName
 113                   (propertyValue).newInstance();
 114               }
 115             catch (Exception e)
 116               {
 117                 System.err.println ("Could not instantiate class: "
 118                                     + propertyValue);
 119                 systemDefaultProvider = new SelectorProviderImpl();
 120               }
 121           }
 122       }
 123
 124     return systemDefaultProvider;
 125   }
 126 }