ServerSocketChannel.java revision 51b1b6997fd3f980076b8081f7f1165ccc2a4008 
1/*
2 * Copyright (c) 2000, 2009, Oracle and/or its affiliates. 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.  Oracle designates this
8 * particular file as subject to the "Classpath" exception as provided
9 * by Oracle 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
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19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
20 *
21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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24 */
25
26package java.nio.channels;
27
28import java.io.IOException;
29import java.net.ServerSocket;
30import java.net.SocketOption;
31import java.net.SocketAddress;
32import java.nio.channels.spi.AbstractSelectableChannel;
33import java.nio.channels.spi.SelectorProvider;
34
35/**
36 * A selectable channel for stream-oriented listening sockets.
37 *
38 * <p> A server-socket channel is created by invoking the {@link #open() open}
39 * method of this class.  It is not possible to create a channel for an arbitrary,
40 * pre-existing {@link ServerSocket}. A newly-created server-socket channel is
41 * open but not yet bound.  An attempt to invoke the {@link #accept() accept}
42 * method of an unbound server-socket channel will cause a {@link NotYetBoundException}
43 * to be thrown. A server-socket channel can be bound by invoking one of the
44 * {@link #bind(java.net.SocketAddress,int) bind} methods defined by this class.
45 *
46 * <p> Socket options are configured using the {@link #setOption(SocketOption,Object)
47 * setOption} method. Server-socket channels support the following options:
48 * <blockquote>
49 * <table border>
50 *   <tr>
51 *     <th>Option Name</th>
52 *     <th>Description</th>
53 *   </tr>
54 *   <tr>
55 *     <td> {@link java.net.StandardSocketOptions#SO_RCVBUF SO_RCVBUF} </td>
56 *     <td> The size of the socket receive buffer </td>
57 *   </tr>
58 *   <tr>
59 *     <td> {@link java.net.StandardSocketOptions#SO_REUSEADDR SO_REUSEADDR} </td>
60 *     <td> Re-use address </td>
61 *   </tr>
62 * </table>
63 * </blockquote>
64 * Additional (implementation specific) options may also be supported.
65 *
66 * <p> Server-socket channels are safe for use by multiple concurrent threads.
67 * </p>
68 *
69 * @author Mark Reinhold
70 * @author JSR-51 Expert Group
71 * @since 1.4
72 */
73
74public abstract class ServerSocketChannel
75    extends AbstractSelectableChannel
76    implements NetworkChannel
77{
78
79    /**
80     * Initializes a new instance of this class.
81     */
82    protected ServerSocketChannel(SelectorProvider provider) {
83        super(provider);
84    }
85
86    /**
87     * Opens a server-socket channel.
88     *
89     * <p> The new channel is created by invoking the {@link
90     * java.nio.channels.spi.SelectorProvider#openServerSocketChannel
91     * openServerSocketChannel} method of the system-wide default {@link
92     * java.nio.channels.spi.SelectorProvider} object.
93     *
94     * <p> The new channel's socket is initially unbound; it must be bound to a
95     * specific address via one of its socket's {@link
96     * java.net.ServerSocket#bind(SocketAddress) bind} methods before
97     * connections can be accepted.  </p>
98     *
99     * @return  A new socket channel
100     *
101     * @throws  IOException
102     *          If an I/O error occurs
103     */
104    public static ServerSocketChannel open() throws IOException {
105        return SelectorProvider.provider().openServerSocketChannel();
106    }
107
108    /**
109     * Returns an operation set identifying this channel's supported
110     * operations.
111     *
112     * <p> Server-socket channels only support the accepting of new
113     * connections, so this method returns {@link SelectionKey#OP_ACCEPT}.
114     * </p>
115     *
116     * @return  The valid-operation set
117     */
118    public final int validOps() {
119        return SelectionKey.OP_ACCEPT;
120    }
121
122
123    // -- ServerSocket-specific operations --
124
125    /**
126     * Binds the channel's socket to a local address and configures the socket
127     * to listen for connections.
128     *
129     * <p> An invocation of this method is equivalent to the following:
130     * <blockquote><pre>
131     * bind(local, 0);
132     * </pre></blockquote>
133     *
134     * @param   local
135     *          The local address to bind the socket, or {@code null} to bind
136     *          to an automatically assigned socket address
137     *
138     * @return  This channel
139     *
140     * @throws  AlreadyBoundException               {@inheritDoc}
141     * @throws  UnsupportedAddressTypeException     {@inheritDoc}
142     * @throws  ClosedChannelException              {@inheritDoc}
143     * @throws  IOException                         {@inheritDoc}
144     * @throws  SecurityException
145     *          If a security manager has been installed and its {@link
146     *          SecurityManager#checkListen checkListen} method denies the
147     *          operation
148     *
149     * @since 1.7
150     */
151    public final ServerSocketChannel bind(SocketAddress local)
152        throws IOException
153    {
154        return bind(local, 0);
155    }
156
157    /**
158     * Binds the channel's socket to a local address and configures the socket to
159     * listen for connections.
160     *
161     * <p> This method is used to establish an association between the socket and
162     * a local address. Once an association is established then the socket remains
163     * bound until the channel is closed.
164     *
165     * <p> The {@code backlog} parameter is the maximum number of pending
166     * connections on the socket. Its exact semantics are implementation specific.
167     * In particular, an implementation may impose a maximum length or may choose
168     * to ignore the parameter altogther. If the {@code backlog} parameter has
169     * the value {@code 0}, or a negative value, then an implementation specific
170     * default is used.
171     *
172     * @param   local
173     *          The address to bind the socket, or {@code null} to bind to an
174     *          automatically assigned socket address
175     * @param   backlog
176     *          The maximum number of pending connections
177     *
178     * @return  This channel
179     *
180     * @throws  AlreadyBoundException
181     *          If the socket is already bound
182     * @throws  UnsupportedAddressTypeException
183     *          If the type of the given address is not supported
184     * @throws  ClosedChannelException
185     *          If this channel is closed
186     * @throws  IOException
187     *          If some other I/O error occurs
188     * @throws  SecurityException
189     *          If a security manager has been installed and its {@link
190     *          SecurityManager#checkListen checkListen} method denies the
191     *          operation
192     *
193     * @since 1.7
194     */
195    public abstract ServerSocketChannel bind(SocketAddress local, int backlog)
196        throws IOException;
197
198    /**
199     * @throws  UnsupportedOperationException           {@inheritDoc}
200     * @throws  IllegalArgumentException                {@inheritDoc}
201     * @throws  ClosedChannelException                  {@inheritDoc}
202     * @throws  IOException                             {@inheritDoc}
203     *
204     * @since 1.7
205     */
206    public abstract <T> ServerSocketChannel setOption(SocketOption<T> name, T value)
207        throws IOException;
208
209    /**
210     * Retrieves a server socket associated with this channel.
211     *
212     * <p> The returned object will not declare any public methods that are not
213     * declared in the {@link java.net.ServerSocket} class.  </p>
214     *
215     * @return  A server socket associated with this channel
216     */
217    public abstract ServerSocket socket();
218
219    /**
220     * Accepts a connection made to this channel's socket.
221     *
222     * <p> If this channel is in non-blocking mode then this method will
223     * immediately return <tt>null</tt> if there are no pending connections.
224     * Otherwise it will block indefinitely until a new connection is available
225     * or an I/O error occurs.
226     *
227     * <p> The socket channel returned by this method, if any, will be in
228     * blocking mode regardless of the blocking mode of this channel.
229     *
230     * <p> This method performs exactly the same security checks as the {@link
231     * java.net.ServerSocket#accept accept} method of the {@link
232     * java.net.ServerSocket} class.  That is, if a security manager has been
233     * installed then for each new connection this method verifies that the
234     * address and port number of the connection's remote endpoint are
235     * permitted by the security manager's {@link
236     * java.lang.SecurityManager#checkAccept checkAccept} method.  </p>
237     *
238     * @return  The socket channel for the new connection,
239     *          or <tt>null</tt> if this channel is in non-blocking mode
240     *          and no connection is available to be accepted
241     *
242     * @throws  ClosedChannelException
243     *          If this channel is closed
244     *
245     * @throws  AsynchronousCloseException
246     *          If another thread closes this channel
247     *          while the accept operation is in progress
248     *
249     * @throws  ClosedByInterruptException
250     *          If another thread interrupts the current thread
251     *          while the accept operation is in progress, thereby
252     *          closing the channel and setting the current thread's
253     *          interrupt status
254     *
255     * @throws  NotYetBoundException
256     *          If this channel's socket has not yet been bound
257     *
258     * @throws  SecurityException
259     *          If a security manager has been installed
260     *          and it does not permit access to the remote endpoint
261     *          of the new connection
262     *
263     * @throws  IOException
264     *          If some other I/O error occurs
265     */
266    public abstract SocketChannel accept() throws IOException;
267
268}
269