Source for java.nio.channels.spi.SelectorProvider

   1: /* SelectorProvider.java
   2:    Copyright (C) 2002, 2003, 2004  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., 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.channels.spi;
  39: 
  40: import gnu.java.nio.SelectorProviderImpl;
  41: 
  42: import java.io.IOException;
  43: import java.nio.channels.DatagramChannel;
  44: import java.nio.channels.Pipe;
  45: import java.nio.channels.ServerSocketChannel;
  46: import java.nio.channels.SocketChannel;
  47: 
  48: 
  49: /**
  50:  * @author Michael Koch
  51:  * @since 1.4
  52:  */
  53: public abstract class SelectorProvider
  54: {
  55:   private static SelectorProvider systemDefaultProvider;
  56: 
  57:   /**
  58:    * Initializes the selector provider.
  59:    *
  60:    * @exception SecurityException If a security manager has been installed and
  61:    * it denies @see RuntimePermission ("selectorProvider").
  62:    */
  63:   protected SelectorProvider()
  64:   {
  65:     SecurityManager sm = System.getSecurityManager();
  66:     if (sm != null)
  67:       sm.checkPermission(new RuntimePermission("selectorProvider"));
  68:   }
  69: 
  70:   /**
  71:    * Opens a datagram channel.
  72:    *
  73:    * @return a new datagram channel object
  74:    * 
  75:    * @exception IOException if an error occurs
  76:    */
  77:   public abstract DatagramChannel openDatagramChannel()
  78:     throws IOException;
  79: 
  80:   /**
  81:    * Opens a pipe.
  82:    *
  83:    * @return a new pipe object
  84:    * 
  85:    * @exception IOException if an error occurs
  86:    */
  87:   public abstract Pipe openPipe() throws IOException;
  88: 
  89:   /**
  90:    * Opens a selector.
  91:    *
  92:    * @return a new selector object
  93:    * 
  94:    * @exception IOException if an error occurs
  95:    */
  96:   public abstract AbstractSelector openSelector() throws IOException;
  97: 
  98:   /**
  99:    * Opens a server socket channel.
 100:    *
 101:    * @return a new server socket channel object
 102:    * 
 103:    * @exception IOException if an error occurs
 104:    */
 105:   public abstract ServerSocketChannel openServerSocketChannel()
 106:     throws IOException;
 107: 
 108:   /**
 109:    * Opens a socket channel.
 110:    *
 111:    * @return a new socket channel object
 112:    * 
 113:    * @exception IOException if an error occurs
 114:    */
 115:   public abstract SocketChannel openSocketChannel() throws IOException;
 116: 
 117:   /**
 118:    * Returns the system-wide default selector provider for this invocation
 119:    * of the Java virtual machine.
 120:    *
 121:    * @return the default seletor provider
 122:    */
 123:   public static synchronized SelectorProvider provider()
 124:   {
 125:     if (systemDefaultProvider == null)
 126:       {
 127:     String propertyValue =
 128:       System.getProperty("java.nio.channels.spi.SelectorProvider");
 129: 
 130:     if (propertyValue == null || propertyValue.equals(""))
 131:       systemDefaultProvider = new SelectorProviderImpl();
 132:     else
 133:       {
 134:         try
 135:           {
 136:         systemDefaultProvider =
 137:           (SelectorProvider) Class.forName(propertyValue)
 138:                                   .newInstance();
 139:           }
 140:         catch (Exception e)
 141:           {
 142:         System.err.println("Could not instantiate class: "
 143:                            + propertyValue);
 144:         systemDefaultProvider = new SelectorProviderImpl();
 145:           }
 146:       }
 147:       }
 148: 
 149:     return systemDefaultProvider;
 150:   }
 151: }