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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
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7    * published by the Free Software Foundation.  Oracle designates this
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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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20   *
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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 <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 }