1/*
2 * Copyright (c) 2000, 2013, 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 summary="Socket options">
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     * @param  provider
83     *         The provider that created this channel
84     */
85    protected ServerSocketChannel(SelectorProvider provider) {
86        super(provider);
87    }
88
89    /**
90     * Opens a server-socket channel.
91     *
92     * <p> The new channel is created by invoking the {@link
93     * java.nio.channels.spi.SelectorProvider#openServerSocketChannel
94     * openServerSocketChannel} method of the system-wide default {@link
95     * java.nio.channels.spi.SelectorProvider} object.
96     *
97     * <p> The new channel's socket is initially unbound; it must be bound to a
98     * specific address via one of its socket's {@link
99     * java.net.ServerSocket#bind(SocketAddress) bind} methods before
100     * connections can be accepted.  </p>
101     *
102     * @return  A new socket channel
103     *
104     * @throws  IOException
105     *          If an I/O error occurs
106     */
107    public static ServerSocketChannel open() throws IOException {
108        return SelectorProvider.provider().openServerSocketChannel();
109    }
110
111    /**
112     * Returns an operation set identifying this channel's supported
113     * operations.
114     *
115     * <p> Server-socket channels only support the accepting of new
116     * connections, so this method returns {@link SelectionKey#OP_ACCEPT}.
117     * </p>
118     *
119     * @return  The valid-operation set
120     */
121    public final int validOps() {
122        return SelectionKey.OP_ACCEPT;
123    }
124
125
126    // -- ServerSocket-specific operations --
127
128    /**
129     * Binds the channel's socket to a local address and configures the socket
130     * to listen for connections.
131     *
132     * <p> An invocation of this method is equivalent to the following:
133     * <blockquote><pre>
134     * bind(local, 0);
135     * </pre></blockquote>
136     *
137     * @param   local
138     *          The local address to bind the socket, or {@code null} to bind
139     *          to an automatically assigned socket address
140     *
141     * @return  This channel
142     *
143     * @throws  AlreadyBoundException               {@inheritDoc}
144     * @throws  UnsupportedAddressTypeException     {@inheritDoc}
145     * @throws  ClosedChannelException              {@inheritDoc}
146     * @throws  IOException                         {@inheritDoc}
147     * @throws  SecurityException
148     *          If a security manager has been installed and its {@link
149     *          SecurityManager#checkListen checkListen} method denies the
150     *          operation
151     *
152     * @since 1.7
153     */
154    public final ServerSocketChannel bind(SocketAddress local)
155        throws IOException
156    {
157        return bind(local, 0);
158    }
159
160    /**
161     * Binds the channel's socket to a local address and configures the socket to
162     * listen for connections.
163     *
164     * <p> This method is used to establish an association between the socket and
165     * a local address. Once an association is established then the socket remains
166     * bound until the channel is closed.
167     *
168     * <p> The {@code backlog} parameter is the maximum number of pending
169     * connections on the socket. Its exact semantics are implementation specific.
170     * In particular, an implementation may impose a maximum length or may choose
171     * to ignore the parameter altogther. If the {@code backlog} parameter has
172     * the value {@code 0}, or a negative value, then an implementation specific
173     * default is used.
174     *
175     * @param   local
176     *          The address to bind the socket, or {@code null} to bind to an
177     *          automatically assigned socket address
178     * @param   backlog
179     *          The maximum number of pending connections
180     *
181     * @return  This channel
182     *
183     * @throws  AlreadyBoundException
184     *          If the socket is already bound
185     * @throws  UnsupportedAddressTypeException
186     *          If the type of the given address is not supported
187     * @throws  ClosedChannelException
188     *          If this channel is closed
189     * @throws  IOException
190     *          If some other I/O error occurs
191     * @throws  SecurityException
192     *          If a security manager has been installed and its {@link
193     *          SecurityManager#checkListen checkListen} method denies the
194     *          operation
195     *
196     * @since 1.7
197     */
198    public abstract ServerSocketChannel bind(SocketAddress local, int backlog)
199        throws IOException;
200
201    /**
202     * @throws  UnsupportedOperationException           {@inheritDoc}
203     * @throws  IllegalArgumentException                {@inheritDoc}
204     * @throws  ClosedChannelException                  {@inheritDoc}
205     * @throws  IOException                             {@inheritDoc}
206     *
207     * @since 1.7
208     */
209    public abstract <T> ServerSocketChannel setOption(SocketOption<T> name, T value)
210        throws IOException;
211
212    /**
213     * Retrieves a server socket associated with this channel.
214     *
215     * <p> The returned object will not declare any public methods that are not
216     * declared in the {@link java.net.ServerSocket} class.  </p>
217     *
218     * @return  A server socket associated with this channel
219     */
220    public abstract ServerSocket socket();
221
222    /**
223     * Accepts a connection made to this channel's socket.
224     *
225     * <p> If this channel is in non-blocking mode then this method will
226     * immediately return <tt>null</tt> if there are no pending connections.
227     * Otherwise it will block indefinitely until a new connection is available
228     * or an I/O error occurs.
229     *
230     * <p> The socket channel returned by this method, if any, will be in
231     * blocking mode regardless of the blocking mode of this channel.
232     *
233     * <p> This method performs exactly the same security checks as the {@link
234     * java.net.ServerSocket#accept accept} method of the {@link
235     * java.net.ServerSocket} class.  That is, if a security manager has been
236     * installed then for each new connection this method verifies that the
237     * address and port number of the connection's remote endpoint are
238     * permitted by the security manager's {@link
239     * java.lang.SecurityManager#checkAccept checkAccept} method.  </p>
240     *
241     * @return  The socket channel for the new connection,
242     *          or <tt>null</tt> if this channel is in non-blocking mode
243     *          and no connection is available to be accepted
244     *
245     * @throws  ClosedChannelException
246     *          If this channel is closed
247     *
248     * @throws  AsynchronousCloseException
249     *          If another thread closes this channel
250     *          while the accept operation is in progress
251     *
252     * @throws  ClosedByInterruptException
253     *          If another thread interrupts the current thread
254     *          while the accept operation is in progress, thereby
255     *          closing the channel and setting the current thread's
256     *          interrupt status
257     *
258     * @throws  NotYetBoundException
259     *          If this channel's socket has not yet been bound
260     *
261     * @throws  SecurityException
262     *          If a security manager has been installed
263     *          and it does not permit access to the remote endpoint
264     *          of the new connection
265     *
266     * @throws  IOException
267     *          If some other I/O error occurs
268     */
269    public abstract SocketChannel accept() throws IOException;
270
271    /**
272     * {@inheritDoc}
273     * <p>
274     * If there is a security manager set, its {@code checkConnect} method is
275     * called with the local address and {@code -1} as its arguments to see
276     * if the operation is allowed. If the operation is not allowed,
277     * a {@code SocketAddress} representing the
278     * {@link java.net.InetAddress#getLoopbackAddress loopback} address and the
279     * local port of the channel's socket is returned.
280     *
281     * @return  The {@code SocketAddress} that the socket is bound to, or the
282     *          {@code SocketAddress} representing the loopback address if
283     *          denied by the security manager, or {@code null} if the
284     *          channel's socket is not bound
285     *
286     * @throws  ClosedChannelException     {@inheritDoc}
287     * @throws  IOException                {@inheritDoc}
288     */
289    @Override
290    public abstract SocketAddress getLocalAddress() throws IOException;
291
292}
293