001 /* SelectionKey.java --
002 Copyright (C) 2002, 2006 Free Software Foundation, Inc.
003
004 This file is part of GNU Classpath.
005
006 GNU Classpath is free software; you can redistribute it and/or modify
007 it under the terms of the GNU General Public License as published by
008 the Free Software Foundation; either version 2, or (at your option)
009 any later version.
010
011 GNU Classpath is distributed in the hope that it will be useful, but
012 WITHOUT ANY WARRANTY; without even the implied warranty of
013 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
014 General Public License for more details.
015
016 You should have received a copy of the GNU General Public License
017 along with GNU Classpath; see the file COPYING. If not, write to the
018 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
019 02110-1301 USA.
020
021 Linking this library statically or dynamically with other modules is
022 making a combined work based on this library. Thus, the terms and
023 conditions of the GNU General Public License cover the whole
024 combination.
025
026 As a special exception, the copyright holders of this library give you
027 permission to link this library with independent modules to produce an
028 executable, regardless of the license terms of these independent
029 modules, and to copy and distribute the resulting executable under
030 terms of your choice, provided that you also meet, for each linked
031 independent module, the terms and conditions of the license of that
032 module. An independent module is a module which is not derived from
033 or based on this library. If you modify this library, you may extend
034 this exception to your version of the library, but you are not
035 obligated to do so. If you do not wish to do so, delete this
036 exception statement from your version. */
037
038 package java.nio.channels;
039
040
041 /**
042 * @author Michael Koch
043 * @since 1.4
044 */
045 public 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 }