libjava/java/nio/channels/SelectionKey.java

   1 /* SelectionKey.java --
   2    Copyright (C) 2002 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;
  39
  40 /**
  41  * @author Michael Koch
  42  * @since 1.4
  43  */
  44 public abstract class SelectionKey
  45 {
  46   public static final int OP_ACCEPT  = 16;
  47   public static final int OP_CONNECT = 8;
  48   public static final int OP_READ    = 1;
  49   public static final int OP_WRITE   = 4;
  50
  51   Object attached;
  52
  53   /**
  54    * Initializes the selection key.
  55    */
  56   protected SelectionKey ()
  57   {
  58   }
  59
  60   /**
  61    * Attaches obj to the key and returns the old attached object.
  62    */
  63   public final Object attach (Object obj)
  64   {
  65     Object old = attached;
  66     attached = obj;
  67     return old;
  68   }
  69
  70   /**
  71    * Returns the object attached to the key.
  72    */
  73   public final Object attachment ()
  74   {
  75     return attached;
  76   }
  77
  78   /**
  79    * Tests if the channel attached to this key is ready to accept
  80    * a new socket connection.
  81    *
  82    * @exception CancelledKeyException If this key has been cancelled
  83    */
  84   public final boolean isAcceptable ()
  85   {
  86     return (readyOps () & OP_ACCEPT) != 0;
  87   }
  88
  89   /**
  90    * Tests whether this key's channel has either finished,
  91    * or failed to finish, its socket-connection operation.
  92    *
  93    * @exception CancelledKeyException If this key has been cancelled
  94    */
  95   public final boolean isConnectable ()
  96   {
  97     return (readyOps () & OP_CONNECT) != 0;
  98   }
  99
 100   /**
 101    * Tests if the channel attached to the key is readable.
 102    *
 103    * @exception CancelledKeyException If this key has been cancelled
 104    */
 105   public final boolean isReadable ()
 106   {
 107     return (readyOps () & OP_READ) != 0;
 108   }
 109
 110   /**
 111    * Tests if the channel attached to the key is writable.
 112    *
 113    * @exception CancelledKeyException If this key has been cancelled
 114    */
 115   public final boolean isWritable ()
 116   {
 117     return (readyOps () & OP_WRITE) != 0;
 118   }
 119
 120   /**
 121    * Requests that the registration of this key's channel with
 122    * its selector be cancelled.
 123    */
 124   public abstract void cancel ();
 125
 126   /**
 127    * return the channel attached to the key.
 128    */
 129   public abstract SelectableChannel channel ();
 130
 131   /**
 132    * Returns the key's interest set.
 133    *
 134    * @exception CancelledKeyException If this key has been cancelled
 135    */
 136   public abstract int interestOps ();
 137
 138   /**
 139    * Sets this key's interest set to the given value.
 140    *
 141    * @exception CancelledKeyException If this key has been cancelled
 142    * @exception IllegalArgumentException If a bit in the set does not
 143    * correspond to an operation that is supported by this key's channel,
 144    * that is, if set &amp; ~(channel().validOps()) != 0
 145    */
 146   public abstract SelectionKey interestOps (int ops);
 147
 148   /**
 149    * Tells whether or not this key is valid.
 150    */
 151   public abstract boolean isValid ();
 152
 153   /**
 154    * Retrieves this key's ready-operation set.
 155    *
 156    * @exception CancelledKeyException If this key has been cancelled
 157    */
 158   public abstract int readyOps ();
 159
 160   /**
 161    * Returns the selector for which this key was created.
 162    */
 163   public abstract Selector selector ();
 164 }