An asynchronous datagram channel is created by invoking one of the {@link - * #open open} methods defined by this class. It is not possible to create a channel - * for an arbitrary, pre-existing datagram socket. A newly-created asynchronous - * datagram channel is open but not connected. It need not be connected in order - * for the {@link #send send} and {@link #receive receive} methods to be used. - * A datagram channel may be connected, by invoking its {@link #connect connect} - * method, in order to avoid the overhead of the security checks that are otherwise - * performed as part of every send and receive operation when a security manager - * is set. The channel must be connected in order to use the {@link #read read} - * and {@link #write write} methods, since those methods do not accept or return - * socket addresses. Once connected, an asynchronous datagram channel remains - * connected until it is disconnected or closed. - * - *
Socket options are configured using the {@link #setOption(SocketOption,Object) - * setOption} method. An asynchronous datagram channel to an Internet Protocol - * (IP) socket supports the following options: - *
- *- * Additional (implementation specific) options may also be supported. - * - *- *
- *- * - *Option Name - *Description - *- * - *{@link java.net.StandardSocketOption#SO_SNDBUF SO_SNDBUF} - *The size of the socket send buffer - *- * - *{@link java.net.StandardSocketOption#SO_RCVBUF SO_RCVBUF} - *The size of the socket receive buffer - *- * - *{@link java.net.StandardSocketOption#SO_REUSEADDR SO_REUSEADDR} - *Re-use address - *- * - *{@link java.net.StandardSocketOption#SO_BROADCAST SO_BROADCAST} - *Allow transmission of broadcast datagrams - *- * - *{@link java.net.StandardSocketOption#IP_TOS IP_TOS} - *The Type of Service (ToS) octet in the Internet Protocol (IP) header - *- * - *{@link java.net.StandardSocketOption#IP_MULTICAST_IF IP_MULTICAST_IF} - *The network interface for Internet Protocol (IP) multicast datagrams - *- * - *{@link java.net.StandardSocketOption#IP_MULTICAST_TTL - * IP_MULTICAST_TTL} - *The time-to-live for Internet Protocol (IP) multicast - * datagrams - *- * - *{@link java.net.StandardSocketOption#IP_MULTICAST_LOOP - * IP_MULTICAST_LOOP} - *Loopback for Internet Protocol (IP) multicast datagrams - *
Asynchronous datagram channels allow more than one read/receive and - * write/send to be oustanding at any given time. - * - *
Usage Example: - *
- * final AsynchronousDatagramChannel dc = AsynchronousDatagramChannel.open()
- * .bind(new InetSocketAddress(4000));
- *
- * // print the source address of all packets that we receive
- * dc.receive(buffer, buffer, new CompletionHandler<SocketAddress,ByteBuffer>() {
- * public void completed(SocketAddress sa, ByteBuffer buffer) {
- * System.out.println(sa);
- * buffer.clear();
- * dc.receive(buffer, buffer, this);
- * }
- * public void failed(Throwable exc, ByteBuffer buffer) {
- * ...
- * }
- * });
- *
- *
- * @since 1.7
- */
-
-public abstract class AsynchronousDatagramChannel
- implements AsynchronousByteChannel, MulticastChannel
-{
- private final AsynchronousChannelProvider provider;
-
- /**
- * Initializes a new instance of this class.
- */
- protected AsynchronousDatagramChannel(AsynchronousChannelProvider provider) {
- this.provider = provider;
- }
-
- /**
- * Returns the provider that created this channel.
- */
- public final AsynchronousChannelProvider provider() {
- return provider;
- }
-
- /**
- * Opens an asynchronous datagram channel.
- *
- * The new channel is created by invoking the {@link - * java.nio.channels.spi.AsynchronousChannelProvider#openAsynchronousDatagramChannel - * openAsynchronousDatagramChannel} method on the {@link - * java.nio.channels.spi.AsynchronousChannelProvider} object that created - * the given group (or the default provider where {@code group} is {@code - * null}). - * - *
The {@code family} parameter is used to specify the {@link ProtocolFamily}. - * If the datagram channel is to be used for Internet Protocol {@link - * MulticastChannel multicasting} then this parameter should correspond to - * the address type of the multicast groups that this channel will join. - * - * @param family - * The protocol family, or {@code null} to use the default protocol - * family - * @param group - * The group to which the newly constructed channel should be bound, - * or {@code null} for the default group - * - * @return A new asynchronous datagram channel - * - * @throws UnsupportedOperationException - * If the specified protocol family is not supported. For example, - * suppose the parameter is specified as {@link - * java.net.StandardProtocolFamily#INET6 INET6} but IPv6 is not - * enabled on the platform. - * @throws ShutdownChannelGroupException - * The specified group is shutdown - * @throws IOException - * If an I/O error occurs - */ - public static AsynchronousDatagramChannel open(ProtocolFamily family, - AsynchronousChannelGroup group) - throws IOException - { - AsynchronousChannelProvider provider = (group == null) ? - AsynchronousChannelProvider.provider() : group.provider(); - return provider.openAsynchronousDatagramChannel(family, group); - } - - /** - * Opens an asynchronous datagram channel. - * - *
This method returns an asynchronous datagram channel that is - * bound to the default group. This method is equivalent to evaluating - * the expression: - *
- * - * @return A new asynchronous datagram channel - * - * @throws IOException - * If an I/O error occurs - */ - public static AsynchronousDatagramChannel open() - throws IOException - { - return open(null, null); - } - - // -- Socket-specific operations -- - - /** - * @throws AlreadyBoundException {@inheritDoc} - * @throws UnsupportedAddressTypeException {@inheritDoc} - * @throws ClosedChannelException {@inheritDoc} - * @throws IOException {@inheritDoc} - * @throws SecurityException - * If a security manager has been installed and its {@link - * SecurityManager#checkListen checkListen} method denies the - * operation - */ - @Override - public abstract AsynchronousDatagramChannel bind(SocketAddress local) - throws IOException; - - /** - * @throws IllegalArgumentException {@inheritDoc} - * @throws ClosedChannelException {@inheritDoc} - * @throws IOException {@inheritDoc} - */ - @Override - public abstract- * open((ProtocolFamily)null, (AsynchronousChannelGroup)null); - *
Where the channel is connected to an Internet Protocol socket address - * then the return value from this method is of type {@link - * java.net.InetSocketAddress}. - * - * @return The remote address; {@code null} if the channel's socket is not - * connected - * - * @throws ClosedChannelException - * If the channel is closed - * @throws IOException - * If an I/O error occurs - */ - public abstract SocketAddress getRemoteAddress() throws IOException; - - /** - * Connects this channel's socket. - * - *
The channel's socket is configured so that it only receives - * datagrams from, and sends datagrams to, the given remote peer - * address. Once connected, datagrams may not be received from or sent to - * any other address. A datagram socket remains connected until it is - * explicitly disconnected or until it is closed. - * - *
This method performs exactly the same security checks as the {@link - * java.net.DatagramSocket#connect connect} method of the {@link - * java.net.DatagramSocket} class. That is, if a security manager has been - * installed then this method verifies that its {@link - * java.lang.SecurityManager#checkAccept checkAccept} and {@link - * java.lang.SecurityManager#checkConnect checkConnect} methods permit - * datagrams to be received from and sent to, respectively, the given - * remote address. - * - *
This method may be invoked at any time. Whether it has any effect - * on outstanding read or write operations is implementation specific and - * therefore not specified. - * - * @param remote - * The remote address to which this channel is to be connected - * - * @return This datagram channel - * - * @throws ClosedChannelException - * If this channel is closed - * - * @throws SecurityException - * If a security manager has been installed - * and it does not permit access to the given remote address - * - * @throws IOException - * If some other I/O error occurs - */ - public abstract AsynchronousDatagramChannel connect(SocketAddress remote) - throws IOException; - - /** - * Disconnects this channel's socket. - * - *
The channel's socket is configured so that it can receive datagrams - * from, and sends datagrams to, any remote address so long as the security - * manager, if installed, permits it. - * - *
This method may be invoked at any time. Whether it has any effect - * on outstanding read or write operations is implementation specific and - * therefore not specified. - * - * @return This datagram channel - * - * @throws IOException - * If some other I/O error occurs - */ - public abstract AsynchronousDatagramChannel disconnect() throws IOException; - - /** - * Receives a datagram via this channel. - * - *
This method initiates the receiving of a datagram into the given - * buffer. The {@code handler} parameter is a completion handler that is - * invoked when the receive operation completes (or fails). The result - * passed to the completion handler is the datagram's source address. - * - *
The datagram is transferred into the given byte buffer starting at - * its current position, as if by a regular {@link AsynchronousByteChannel#read - * read} operation. If there are fewer bytes remaining in the buffer - * than are required to hold the datagram then the remainder of the datagram - * is silently discarded. - * - *
If a timeout is specified and the timeout elapses before the operation - * completes then the operation completes with the exception {@link - * InterruptedByTimeoutException}. When a timeout elapses then the state of - * the {@link ByteBuffer} is not defined. The buffers should be discarded or - * at least care must be taken to ensure that the buffer is not accessed - * while the channel remains open. - * - *
When a security manager has been installed and the channel is not
- * connected, then it verifies that the source's address and port number are
- * permitted by the security manager's {@link SecurityManager#checkAccept
- * checkAccept} method. The permission check is performed with privileges that
- * are restricted by the calling context of this method. If the permission
- * check fails then the operation completes with a {@link SecurityException}.
- * The overhead of this security check can be avoided by first connecting the
- * socket via the {@link #connect connect} method.
- *
- * @param dst
- * The buffer into which the datagram is to be transferred
- * @param timeout
- * The timeout, or {@code 0L} for no timeout
- * @param unit
- * The time unit of the {@code timeout} argument
- * @param attachment
- * The object to attach to the I/O operation; can be {@code null}
- * @param handler
- * The handler for consuming the result
- *
- * @throws IllegalArgumentException
- * If the timeout is negative or the buffer is read-only
- * @throws ShutdownChannelGroupException
- * If the channel group has terminated
- */
- public abstract void receive(ByteBuffer dst,
- long timeout,
- TimeUnit unit,
- A attachment,
- CompletionHandler This method initiates the receiving of a datagram into the given
- * buffer. The {@code handler} parameter is a completion handler that is
- * invoked when the receive operation completes (or fails). The result
- * passed to the completion handler is the datagram's source address.
- *
- * This method is equivalent to invoking {@link
- * #receive(ByteBuffer,long,TimeUnit,Object,CompletionHandler)} with a
- * timeout of {@code 0L}.
- *
- * @param dst
- * The buffer into which the datagram is to be transferred
- * @param attachment
- * The object to attach to the I/O operation; can be {@code null}
- * @param handler
- * The handler for consuming the result
- *
- * @throws IllegalArgumentException
- * If the buffer is read-only
- * @throws ShutdownChannelGroupException
- * If the channel group has terminated
- */
- public final void receive(ByteBuffer dst,
- A attachment,
- CompletionHandler This method initiates the receiving of a datagram into the given
- * buffer. The method behaves in exactly the same manner as the {@link
- * #receive(ByteBuffer,Object,CompletionHandler)
- * receive(ByteBuffer,Object,CompletionHandler)} method except that instead
- * of specifying a completion handler, this method returns a {@code Future}
- * representing the pending result. The {@code Future}'s {@link Future#get()
- * get} method returns the datagram's source address.
- *
- * @param dst
- * The buffer into which the datagram is to be transferred
- *
- * @return a {@code Future} object representing the pending result
- *
- * @throws IllegalArgumentException
- * If the buffer is read-only
- */
- public abstract Future This method initiates sending of a datagram from the given buffer to
- * the given address. The {@code handler} parameter is a completion handler
- * that is invoked when the send completes (or fails). The result passed to
- * the completion handler is the number of bytes sent.
- *
- * Otherwise this method works in the same manner as the {@link
- * AsynchronousByteChannel#write(ByteBuffer,Object,CompletionHandler)}
- * method.
- *
- * @param src
- * The buffer containing the datagram to be sent
- * @param target
- * The address to which the datagram is to be sent
- * @param attachment
- * The object to attach to the I/O operation; can be {@code null}
- * @param handler
- * The handler for consuming the result
- *
- * @throws UnresolvedAddressException
- * If the given remote address is not fully resolved
- * @throws UnsupportedAddressTypeException
- * If the type of the given remote address is not supported
- * @throws IllegalArgumentException
- * If the channel's socket is connected and is connected to an
- * address that is not equal to {@code target}
- * @throws SecurityException
- * If a security manager has been installed and it does not permit
- * datagrams to be sent to the given address
- * @throws ShutdownChannelGroupException
- * If the channel group has terminated
- */
- public abstract void send(ByteBuffer src,
- SocketAddress target,
- A attachment,
- CompletionHandler This method initiates sending of a datagram from the given buffer to
- * the given address. The method behaves in exactly the same manner as the
- * {@link #send(ByteBuffer,SocketAddress,Object,CompletionHandler)
- * send(ByteBuffer,SocketAddress,Object,CompletionHandler)} method except
- * that instead of specifying a completion handler, this method returns a
- * {@code Future} representing the pending result. The {@code Future}'s
- * {@link Future#get() get} method returns the number of bytes sent.
- *
- * @param src
- * The buffer containing the datagram to be sent
- * @param target
- * The address to which the datagram is to be sent
- *
- * @return a {@code Future} object representing the pending result
- *
- * @throws UnresolvedAddressException
- * If the given remote address is not fully resolved
- * @throws UnsupportedAddressTypeException
- * If the type of the given remote address is not supported
- * @throws IllegalArgumentException
- * If the channel's socket is connected and is connected to an
- * address that is not equal to {@code target}
- * @throws SecurityException
- * If a security manager has been installed and it does not permit
- * datagrams to be sent to the given address
- */
- public abstract Future This method initiates the receiving of a datagram into the given
- * buffer. The {@code handler} parameter is a completion handler that is
- * invoked when the receive operation completes (or fails). The result
- * passed to the completion handler is number of bytes read.
- *
- * This method may only be invoked if this channel is connected, and it
- * only accepts datagrams from the peer that the channel is connected too.
- * The datagram is transferred into the given byte buffer starting at
- * its current position and exactly as specified in the {@link
- * AsynchronousByteChannel} interface. If there are fewer bytes
- * remaining in the buffer than are required to hold the datagram then the
- * remainder of the datagram is silently discarded.
- *
- * If a timeout is specified and the timeout elapses before the operation
- * completes then the operation completes with the exception {@link
- * InterruptedByTimeoutException}. When a timeout elapses then the state of
- * the {@link ByteBuffer} is not defined. The buffers should be discarded or
- * at least care must be taken to ensure that the buffer is not accessed
- * while the channel remains open.
- *
- * @param dst
- * The buffer into which the datagram is to be transferred
- * @param timeout
- * The timeout, or {@code 0L} for no timeout
- * @param unit
- * The time unit of the {@code timeout} argument
- * @param attachment
- * The object to attach to the I/O operation; can be {@code null}
- * @param handler
- * The handler for consuming the result
- *
- * @throws IllegalArgumentException
- * If the timeout is negative or buffer is read-only
- * @throws NotYetConnectedException
- * If this channel is not connected
- * @throws ShutdownChannelGroupException
- * If the channel group has terminated
- */
- public abstract void read(ByteBuffer dst,
- long timeout,
- TimeUnit unit,
- A attachment,
- CompletionHandler