001/* SelectionKey.java --
002   Copyright (C) 2002, 2006 Free Software Foundation, Inc.
003
004This file is part of GNU Classpath.
005
006GNU Classpath is free software; you can redistribute it and/or modify
007it under the terms of the GNU General Public License as published by
008the Free Software Foundation; either version 2, or (at your option)
009any later version.
010
011GNU Classpath is distributed in the hope that it will be useful, but
012WITHOUT ANY WARRANTY; without even the implied warranty of
013MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
014General Public License for more details.
015
016You should have received a copy of the GNU General Public License
017along with GNU Classpath; see the file COPYING.  If not, write to the
018Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
01902110-1301 USA.
020
021Linking this library statically or dynamically with other modules is
022making a combined work based on this library.  Thus, the terms and
023conditions of the GNU General Public License cover the whole
024combination.
025
026As a special exception, the copyright holders of this library give you
027permission to link this library with independent modules to produce an
028executable, regardless of the license terms of these independent
029modules, and to copy and distribute the resulting executable under
030terms of your choice, provided that you also meet, for each linked
031independent module, the terms and conditions of the license of that
032module.  An independent module is a module which is not derived from
033or based on this library.  If you modify this library, you may extend
034this exception to your version of the library, but you are not
035obligated to do so.  If you do not wish to do so, delete this
036exception statement from your version. */
037
038package java.nio.channels;
039
040
041/**
042 * @author Michael Koch
043 * @since 1.4
044 */
045public abstract class SelectionKey
046{
047  public static final int OP_ACCEPT = 16;
048  public static final int OP_CONNECT = 8;
049  public static final int OP_READ = 1;
050  public static final int OP_WRITE = 4;
051  Object attached;
052
053  /**
054   * Initializes the selection key.
055   */
056  protected SelectionKey()
057  {
058  }
059
060  /**
061   * Attaches obj to the key and returns the old attached object.
062   */
063  public final synchronized Object attach(Object obj)
064  {
065    Object old = attached;
066    attached = obj;
067    return old;
068  }
069
070  /**
071   * Returns the object attached to the key.
072   */
073  public final synchronized Object attachment()
074  {
075    return attached;
076  }
077
078  /**
079   * Tests if the channel attached to this key is ready to accept
080   * a new socket connection.
081   *
082   * @exception CancelledKeyException If this key has been cancelled
083   */
084  public final boolean isAcceptable()
085  {
086    return (readyOps() & OP_ACCEPT) != 0;
087  }
088
089  /**
090   * Tests whether this key's channel has either finished,
091   * or failed to finish, its socket-connection operation.
092   *
093   * @exception CancelledKeyException If this key has been cancelled
094   */
095  public final boolean isConnectable()
096  {
097    return (readyOps() & OP_CONNECT) != 0;
098  }
099
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 & ~(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}