1 /*
2 * Copyright 2000-2003 Sun Microsystems, Inc. All Rights Reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation. Sun designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Sun in the LICENSE file that accompanied this code.
10 *
11 * This code is distributed in the hope that it will be useful, but WITHOUT
12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
14 * version 2 for more details (a copy is included in the LICENSE file that
15 * accompanied this code).
16 *
17 * You should have received a copy of the GNU General Public License version
18 * 2 along with this work; if not, write to the Free Software Foundation,
19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
22 * CA 95054 USA or visit www.sun.com if you need additional information or
23 * have any questions.
24 */
25
26 package java.nio.channels;
27
28 import java.io.IOException;
29 import java.io.Closeable;
30
31
32 /**
33 * A nexus for I/O operations.
34 *
35 * <p> A channel represents an open connection to an entity such as a hardware
36 * device, a file, a network socket, or a program component that is capable of
37 * performing one or more distinct I/O operations, for example reading or
38 * writing.
39 *
40 * <p> A channel is either open or closed. A channel is open upon creation,
41 * and once closed it remains closed. Once a channel is closed, any attempt to
42 * invoke an I/O operation upon it will cause a {@link ClosedChannelException}
43 * to be thrown. Whether or not a channel is open may be tested by invoking
44 * its {@link #isOpen isOpen} method.
45 *
46 * <p> Channels are, in general, intended to be safe for multithreaded access
47 * as described in the specifications of the interfaces and classes that extend
48 * and implement this interface.
49 *
50 *
51 * @author Mark Reinhold
52 * @author JSR-51 Expert Group
53 * @since 1.4
54 */
55
56 public interface Channel extends Closeable {
57
58 /**
59 * Tells whether or not this channel is open. </p>
60 *
61 * @return <tt>true</tt> if, and only if, this channel is open
62 */
63 public boolean isOpen();
64
65 /**
66 * Closes this channel.
67 *
68 * <p> After a channel is closed, any further attempt to invoke I/O
69 * operations upon it will cause a {@link ClosedChannelException} to be
70 * thrown.
71 *
72 * <p> If this channel is already closed then invoking this method has no
73 * effect.
74 *
75 * <p> This method may be invoked at any time. If some other thread has
76 * already invoked it, however, then another invocation will block until
77 * the first invocation is complete, after which it will return without
78 * effect. </p>
79 *
80 * @throws IOException If an I/O error occurs
81 */
82 public void close() throws IOException;
83
84 }
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