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
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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
22 * or visit www.oracle.com if you need additional information or have any
23 * questions.
24 */
25
26 package java.nio.channels;
27
28 import java.io.IOException;
29 import java.net.ServerSocket;
30 import java.net.SocketOption;
31 import java.net.SocketAddress;
32 import java.nio.channels.spi.AbstractSelectableChannel;
33 import 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
74 public 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 {@code null} 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 {@code null} 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 }