https://openjdk.java.net/ 
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * particular file as subject to the "Classpath" exception as provided
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 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
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package java.nio.channels;

import java.nio.channels.spi.*;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.Future;
import java.io.IOException;
import java.net.SocketOption;
import java.net.SocketAddress;
import java.nio.ByteBuffer;


An asynchronous channel for stream-oriented connecting sockets.

 Asynchronous socket channels are created in one of two ways. A newly-created AsynchronousSocketChannel is created by invoking one of the open methods defined by this class. A newly-created channel is open but not yet connected. A connected AsynchronousSocketChannel is created when a connection is made to the socket of an AsynchronousServerSocketChannel. It is not possible to create an asynchronous socket channel for an arbitrary, pre-existing socket. 
 A newly-created channel is connected by invoking its connect method; once connected, a channel remains connected until it is closed. Whether or not a socket channel is connected may be determined by invoking its getRemoteAddress method. An attempt to invoke an I/O operation upon an unconnected channel will cause a NotYetConnectedException to be thrown. 
 Channels of this type are safe for use by multiple concurrent threads. They support concurrent reading and writing, though at most one read operation and one write operation can be outstanding at any time. If a thread initiates a read operation before a previous read operation has completed then a ReadPendingException will be thrown. Similarly, an attempt to initiate a write operation before a previous write has completed will throw a WritePendingException. 
 Socket options are configured using the 
setOption method. Asynchronous socket channels support the following options: 



Socket options

  

    Option Name
    Description
  



  

     SO_SNDBUF 
     The size of the socket send buffer 
  

  

     SO_RCVBUF 
     The size of the socket receive buffer 
  

  

     SO_KEEPALIVE 
     Keep connection alive 
  

  

     SO_REUSEADDR 
     Re-use address 
  

  

     TCP_NODELAY 
     Disable the Nagle algorithm 
  






Additional (implementation specific) options may also be supported.

Timeouts


 The read and write methods defined by this class allow a timeout to be specified when initiating a read or write operation. If the timeout elapses before an operation completes then the operation completes with the exception InterruptedByTimeoutException. A timeout may leave the channel, or the underlying connection, in an inconsistent state. Where the implementation cannot guarantee that bytes have not been read from the channel then it puts the channel into an implementation specific error state. A subsequent attempt to initiate a read operation causes an unspecified runtime exception to be thrown. Similarly if a write operation times out and the implementation cannot guarantee bytes have not been written to the channel then further attempts to write to the channel cause an unspecified runtime exception to be thrown. When a timeout elapses then the state of the ByteBuffer, or the sequence of buffers, for the I/O operation is not defined. Buffers should be discarded or at least care must be taken to ensure that the buffers are not accessed while the channel remains open. All methods that accept timeout parameters treat values less than or equal to zero to mean that the I/O operation does not timeout. 
Since:1.7
/**
 * An asynchronous channel for stream-oriented connecting sockets.
 *
 * <p> Asynchronous socket channels are created in one of two ways. A newly-created
 * {@code AsynchronousSocketChannel} is created by invoking one of the {@link
 * #open open} methods defined by this class. A newly-created channel is open but
 * not yet connected. A connected {@code AsynchronousSocketChannel} is created
 * when a connection is made to the socket of an {@link AsynchronousServerSocketChannel}.
 * It is not possible to create an asynchronous socket channel for an arbitrary,
 * pre-existing {@link java.net.Socket socket}.
 *
 * <p> A newly-created channel is connected by invoking its {@link #connect connect}
 * method; once connected, a channel remains connected until it is closed.  Whether
 * or not a socket channel is connected may be determined by invoking its {@link
 * #getRemoteAddress getRemoteAddress} method. An attempt to invoke an I/O
 * operation upon an unconnected channel will cause a {@link NotYetConnectedException}
 * to be thrown.
 *
 * <p> Channels of this type are safe for use by multiple concurrent threads.
 * They support concurrent reading and writing, though at most one read operation
 * and one write operation can be outstanding at any time.
 * If a thread initiates a read operation before a previous read operation has
 * completed then a {@link ReadPendingException} will be thrown. Similarly, an
 * attempt to initiate a write operation before a previous write has completed
 * will throw a {@link WritePendingException}.
 *
 * <p> Socket options are configured using the {@link #setOption(SocketOption,Object)
 * setOption} method. Asynchronous socket channels support the following options:
 * <blockquote>
 * <table class="striped">
 * <caption style="display:none">Socket options</caption>
 * <thead>
 *   <tr>
 *     <th scope="col">Option Name</th>
 *     <th scope="col">Description</th>
 *   </tr>
 * </thead>
 * <tbody>
 *   <tr>
 *     <th scope="row"> {@link java.net.StandardSocketOptions#SO_SNDBUF SO_SNDBUF} </th>
 *     <td> The size of the socket send buffer </td>
 *   </tr>
 *   <tr>
 *     <th scope="row"> {@link java.net.StandardSocketOptions#SO_RCVBUF SO_RCVBUF} </th>
 *     <td> The size of the socket receive buffer </td>
 *   </tr>
 *   <tr>
 *     <th scope="row"> {@link java.net.StandardSocketOptions#SO_KEEPALIVE SO_KEEPALIVE} </th>
 *     <td> Keep connection alive </td>
 *   </tr>
 *   <tr>
 *     <th scope="row"> {@link java.net.StandardSocketOptions#SO_REUSEADDR SO_REUSEADDR} </th>
 *     <td> Re-use address </td>
 *   </tr>
 *   <tr>
 *     <th scope="row"> {@link java.net.StandardSocketOptions#TCP_NODELAY TCP_NODELAY} </th>
 *     <td> Disable the Nagle algorithm </td>
 *   </tr>
 * </tbody>
 * </table>
 * </blockquote>
 * Additional (implementation specific) options may also be supported.
 *
 * <h2>Timeouts</h2>
 *
 * <p> The {@link #read(ByteBuffer,long,TimeUnit,Object,CompletionHandler) read}
 * and {@link #write(ByteBuffer,long,TimeUnit,Object,CompletionHandler) write}
 * methods defined by this class allow a timeout to be specified when initiating
 * a read or write operation. If the timeout elapses before an operation completes
 * then the operation completes with the exception {@link
 * InterruptedByTimeoutException}. A timeout may leave the channel, or the
 * underlying connection, in an inconsistent state. Where the implementation
 * cannot guarantee that bytes have not been read from the channel then it puts
 * the channel into an implementation specific <em>error state</em>. A subsequent
 * attempt to initiate a {@code read} operation causes an unspecified runtime
 * exception to be thrown. Similarly if a {@code write} operation times out and
 * the implementation cannot guarantee bytes have not been written to the
 * channel then further attempts to {@code write} to the channel cause an
 * unspecified runtime exception to be thrown. When a timeout elapses then the
 * state of the {@link ByteBuffer}, or the sequence of buffers, for the I/O
 * operation is not defined. Buffers should be discarded or at least care must
 * be taken to ensure that the buffers are not accessed while the channel remains
 * open. All methods that accept timeout parameters treat values less than or
 * equal to zero to mean that the I/O operation does not timeout.
 *
 * @since 1.7
 */

public abstract class AsynchronousSocketChannel
    implements AsynchronousByteChannel, NetworkChannel
{
    private final AsynchronousChannelProvider provider;

    
Initializes a new instance of this class.

Params:
  • provider – 
        The provider that created this channel
/**
     * Initializes a new instance of this class.
     *
     * @param  provider
     *         The provider that created this channel
     */
    protected AsynchronousSocketChannel(AsynchronousChannelProvider provider) {
        this.provider = provider;
    }

    
Returns the provider that created this channel.

Returns: The provider that created this channel
/**
     * Returns the provider that created this channel.
     *
     * @return  The provider that created this channel
     */
    public final AsynchronousChannelProvider provider() {
        return provider;
    }

    
Opens an asynchronous socket channel.

 The new channel is created by invoking the 
openAsynchronousSocketChannel method on the AsynchronousChannelProvider that created the group. If the group parameter is null then the resulting channel is created by the system-wide default provider, and bound to the default group.

Params:
  • group –  The group to which the newly constructed channel should be bound, or null for the default group
Throws:
Returns: A new asynchronous socket channel
/**
     * Opens an asynchronous socket channel.
     *
     * <p> The new channel is created by invoking the {@link
     * AsynchronousChannelProvider#openAsynchronousSocketChannel
     * openAsynchronousSocketChannel} method on the {@link
     * AsynchronousChannelProvider} that created the group. If the group parameter
     * is {@code null} then the resulting channel is created by the system-wide
     * default provider, and bound to the <em>default group</em>.
     *
     * @param   group
     *          The group to which the newly constructed channel should be bound,
     *          or {@code null} for the default group
     *
     * @return  A new asynchronous socket channel
     *
     * @throws  ShutdownChannelGroupException
     *          If the channel group is shutdown
     * @throws  IOException
     *          If an I/O error occurs
     */
    public static AsynchronousSocketChannel open(AsynchronousChannelGroup group)
        throws IOException
    {
        AsynchronousChannelProvider provider = (group == null) ?
            AsynchronousChannelProvider.provider() : group.provider();
        return provider.openAsynchronousSocketChannel(group);
    }

    
Opens an asynchronous socket channel.

 This method returns an asynchronous socket channel that is bound to
the default group.This method is equivalent to evaluating the
expression:

open((AsynchronousChannelGroup)null);



Throws:
Returns: A new asynchronous socket channel
/**
     * Opens an asynchronous socket channel.
     *
     * <p> This method returns an asynchronous socket channel that is bound to
     * the <em>default group</em>.This method is equivalent to evaluating the
     * expression:
     * <blockquote><pre>
     * open((AsynchronousChannelGroup)null);
     * </pre></blockquote>
     *
     * @return  A new asynchronous socket channel
     *
     * @throws  IOException
     *          If an I/O error occurs
     */
    public static AsynchronousSocketChannel open()
        throws IOException
    {
        return open(null);
    }


    // -- socket options and related --

    
Throws:
/**
     * @throws  ConnectionPendingException
     *          If a connection operation is already in progress on this channel
     * @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 AsynchronousSocketChannel bind(SocketAddress local)
        throws IOException;

    
Throws:
/**
     * @throws  IllegalArgumentException                {@inheritDoc}
     * @throws  ClosedChannelException                  {@inheritDoc}
     * @throws  IOException                             {@inheritDoc}
     */
    @Override
    public abstract <T> AsynchronousSocketChannel setOption(SocketOption<T> name, T value)
        throws IOException;

    
Shutdown the connection for reading without closing the channel.

 Once shutdown for reading then further reads on the channel will return -1, the end-of-stream indication. If the input side of the connection is already shutdown then invoking this method has no effect. The effect on an outstanding read operation is system dependent and therefore not specified. The effect, if any, when there is data in the socket receive buffer that has not been read, or data arrives subsequently, is also system dependent. 
Throws:
Returns: The channel
/**
     * Shutdown the connection for reading without closing the channel.
     *
     * <p> Once shutdown for reading then further reads on the channel will
     * return {@code -1}, the end-of-stream indication. If the input side of the
     * connection is already shutdown then invoking this method has no effect.
     * The effect on an outstanding read operation is system dependent and
     * therefore not specified. The effect, if any, when there is data in the
     * socket receive buffer that has not been read, or data arrives subsequently,
     * is also system dependent.
     *
     * @return  The channel
     *
     * @throws  NotYetConnectedException
     *          If this channel is not yet connected
     * @throws  ClosedChannelException
     *          If this channel is closed
     * @throws  IOException
     *          If some other I/O error occurs
     */
    public abstract AsynchronousSocketChannel shutdownInput() throws IOException;

    
Shutdown the connection for writing without closing the channel.

 Once shutdown for writing then further attempts to write to the channel will throw ClosedChannelException. If the output side of the connection is already shutdown then invoking this method has no effect. The effect on an outstanding write operation is system dependent and therefore not specified. 
Throws:
Returns: The channel
/**
     * Shutdown the connection for writing without closing the channel.
     *
     * <p> Once shutdown for writing then further attempts to write to the
     * channel will throw {@link ClosedChannelException}. If the output side of
     * the connection is already shutdown then invoking this method has no
     * effect. The effect on an outstanding write operation is system dependent
     * and therefore not specified.
     *
     * @return  The channel
     *
     * @throws  NotYetConnectedException
     *          If this channel is not yet connected
     * @throws  ClosedChannelException
     *          If this channel is closed
     * @throws  IOException
     *          If some other I/O error occurs
     */
    public abstract AsynchronousSocketChannel shutdownOutput() throws IOException;

    // -- state --

    
Returns the remote address to which this channel's socket is connected.

 Where the channel is bound and connected to an Internet Protocol socket address then the return value from this method is of type InetSocketAddress. 
Throws:
Returns: The remote address; null if the channel's socket is not connected
/**
     * Returns the remote address to which this channel's socket is connected.
     *
     * <p> Where the channel is bound and 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;

    // -- asynchronous operations --

    
Connects this channel.

 This method initiates an operation to connect this channel. The handler parameter is a completion handler that is invoked when the connection is successfully established or connection cannot be established. If the connection cannot be established then the channel is closed. 
 This method performs exactly the same security checks as the Socket class. That is, if a security manager has been installed then this method verifies that its checkConnect method permits connecting to the address and port number of the given remote endpoint. 
Params:
  • remote – 
         The remote address to which this channel is to be connected
  • attachment –  The object to attach to the I/O operation; can be null
  • handler – 
         The handler for consuming the result
Type parameters:
  • <A> – 
         The type of the attachment
Throws:
See Also:
/**
     * Connects this channel.
     *
     * <p> This method initiates an operation to connect this channel. The
     * {@code handler} parameter is a completion handler that is invoked when
     * the connection is successfully established or connection cannot be
     * established. If the connection cannot be established then the channel is
     * closed.
     *
     * <p> This method performs exactly the same security checks as the {@link
     * java.net.Socket} class.  That is, if a security manager has been
     * installed then this method verifies that its {@link
     * java.lang.SecurityManager#checkConnect checkConnect} method permits
     * connecting to the address and port number of the given remote endpoint.
     *
     * @param   <A>
     *          The type of the attachment
     * @param   remote
     *          The remote address to which this channel is to be connected
     * @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  AlreadyConnectedException
     *          If this channel is already connected
     * @throws  ConnectionPendingException
     *          If a connection operation is already in progress on this channel
     * @throws  ShutdownChannelGroupException
     *          If the channel group has terminated
     * @throws  SecurityException
     *          If a security manager has been installed
     *          and it does not permit access to the given remote endpoint
     *
     * @see #getRemoteAddress
     */
    public abstract <A> void connect(SocketAddress remote,
                                     A attachment,
                                     CompletionHandler<Void,? super A> handler);

    
Connects this channel.

 This method initiates an operation to connect this channel. This method behaves in exactly the same manner as the connect(SocketAddress, Object, CompletionHandler<Void,? super Object>) method except that instead of specifying a completion handler, this method returns a 
Future representing the pending result. The Future's get method returns null on successful completion. 
Params:
  • remote – 
         The remote address to which this channel is to be connected
Throws:
Returns: A Future object representing the pending result
/**
     * Connects this channel.
     *
     * <p> This method initiates an operation to connect this channel. This
     * method behaves in exactly the same manner as the {@link
     * #connect(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 {@code null} on successful completion.
     *
     * @param   remote
     *          The remote address to which this channel is to be connected
     *
     * @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  AlreadyConnectedException
     *          If this channel is already connected
     * @throws  ConnectionPendingException
     *          If a connection operation is already in progress on this channel
     * @throws  SecurityException
     *          If a security manager has been installed
     *          and it does not permit access to the given remote endpoint
     */
    public abstract Future<Void> connect(SocketAddress remote);

    
Reads a sequence of bytes from this channel into the given buffer.

 This method initiates an asynchronous read operation to read a sequence of bytes from this channel into the given buffer. The 
handler parameter is a completion handler that is invoked when the read operation completes (or fails). The result passed to the completion handler is the number of bytes read or -1 if no bytes could be read because the channel has reached end-of-stream. 
 If a timeout is specified and the timeout elapses before the operation completes then the operation completes with the exception InterruptedByTimeoutException. Where a timeout occurs, and the implementation cannot guarantee that bytes have not been read, or will not be read from the channel into the given buffer, then further attempts to read from the channel will cause an unspecific runtime exception to be thrown. 
 Otherwise this method works in the same manner as the AsynchronousByteChannel.read(ByteBuffer, Object, CompletionHandler<Integer,? super Object>) method. 
Params:
  • dst – 
         The buffer into which bytes are to be transferred
  • timeout – 
         The maximum time for the I/O operation to complete
  • unit –  The time unit of the timeout argument
  • attachment –  The object to attach to the I/O operation; can be null
  • handler – 
         The handler for consuming the result
Type parameters:
  • <A> – 
         The type of the attachment
Throws:
/**
     * Reads a sequence of bytes from this channel into the given buffer.
     *
     * <p> This method initiates an asynchronous read operation to read a
     * sequence of bytes from this channel into the given buffer. The {@code
     * handler} parameter is a completion handler that is invoked when the read
     * operation completes (or fails). The result passed to the completion
     * handler is the number of bytes read or {@code -1} if no bytes could be
     * read because the channel has reached end-of-stream.
     *
     * <p> If a timeout is specified and the timeout elapses before the operation
     * completes then the operation completes with the exception {@link
     * InterruptedByTimeoutException}. Where a timeout occurs, and the
     * implementation cannot guarantee that bytes have not been read, or will not
     * be read from the channel into the given buffer, then further attempts to
     * read from the channel will cause an unspecific runtime exception to be
     * thrown.
     *
     * <p> Otherwise this method works in the same manner as the {@link
     * AsynchronousByteChannel#read(ByteBuffer,Object,CompletionHandler)}
     * method.
     *
     * @param   <A>
     *          The type of the attachment
     * @param   dst
     *          The buffer into which bytes are to be transferred
     * @param   timeout
     *          The maximum time for the I/O operation to complete
     * @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 buffer is read-only
     * @throws  ReadPendingException
     *          If a read operation is already in progress on this channel
     * @throws  NotYetConnectedException
     *          If this channel is not yet connected
     * @throws  ShutdownChannelGroupException
     *          If the channel group has terminated
     */
    public abstract <A> void read(ByteBuffer dst,
                                  long timeout,
                                  TimeUnit unit,
                                  A attachment,
                                  CompletionHandler<Integer,? super A> handler);

    
Throws:
/**
     * @throws  IllegalArgumentException        {@inheritDoc}
     * @throws  ReadPendingException            {@inheritDoc}
     * @throws  NotYetConnectedException
     *          If this channel is not yet connected
     * @throws  ShutdownChannelGroupException
     *          If the channel group has terminated
     */
    @Override
    public final <A> void read(ByteBuffer dst,
                               A attachment,
                               CompletionHandler<Integer,? super A> handler)
    {
        read(dst, 0L, TimeUnit.MILLISECONDS, attachment, handler);
    }

    
Throws:
/**
     * @throws  IllegalArgumentException        {@inheritDoc}
     * @throws  ReadPendingException            {@inheritDoc}
     * @throws  NotYetConnectedException
     *          If this channel is not yet connected
     */
    @Override
    public abstract Future<Integer> read(ByteBuffer dst);

    
Reads a sequence of bytes from this channel into a subsequence of the
given buffers. This operation, sometimes called a scattering read, is often useful when implementing network protocols that group data into segments consisting of one or more fixed-length headers followed by a variable-length body. The handler parameter is a completion handler that is invoked when the read operation completes (or fails). The result passed to the completion handler is the number of bytes read or -1 if no bytes could be read because the channel has reached end-of-stream. 
 This method initiates a read of up to r bytes from this channel,
where r is the total number of bytes remaining in the specified
subsequence of the given buffer array, that is,

dsts[offset].remaining()
    + dsts[offset+1].remaining()
    + ... + dsts[offset+length-1].remaining()

at the moment that the read is attempted.

 Suppose that a byte sequence of length n is read, where 0 < n <= r. Up to the first dsts[offset].remaining() bytes of this sequence are transferred into buffer dsts[offset], up to the next dsts[offset+1].remaining() bytes are transferred into buffer dsts[offset+1], and so forth, until the entire byte sequence is transferred into the given buffers. As many bytes as possible are transferred into each buffer, hence the final position of each updated buffer, except the last updated buffer, is guaranteed to be equal to that buffer's limit. The underlying operating system may impose a limit on the number of buffers that may be used in an I/O operation. Where the number of buffers (with bytes remaining), exceeds this limit, then the I/O operation is performed with the maximum number of buffers allowed by the operating system. 
 If a timeout is specified and the timeout elapses before the operation completes then it completes with the exception InterruptedByTimeoutException. Where a timeout occurs, and the implementation cannot guarantee that bytes have not been read, or will not be read from the channel into the given buffers, then further attempts to read from the channel will cause an unspecific runtime exception to be thrown. 
Params:
  • dsts – 
         The buffers into which bytes are to be transferred
  • offset –  The offset within the buffer array of the first buffer into which bytes are to be transferred; must be non-negative and no larger than dsts.length
  • length –  The maximum number of buffers to be accessed; must be non-negative and no larger than dsts.length - offset
  • timeout – 
         The maximum time for the I/O operation to complete
  • unit –  The time unit of the timeout argument
  • attachment –  The object to attach to the I/O operation; can be null
  • handler – 
         The handler for consuming the result
Type parameters:
  • <A> – 
         The type of the attachment
Throws:
/**
     * Reads a sequence of bytes from this channel into a subsequence of the
     * given buffers. This operation, sometimes called a <em>scattering read</em>,
     * is often useful when implementing network protocols that group data into
     * segments consisting of one or more fixed-length headers followed by a
     * variable-length body. The {@code handler} parameter is a completion
     * handler that is invoked when the read operation completes (or fails). The
     * result passed to the completion handler is the number of bytes read or
     * {@code -1} if no bytes could be read because the channel has reached
     * end-of-stream.
     *
     * <p> This method initiates a read of up to <i>r</i> bytes from this channel,
     * where <i>r</i> is the total number of bytes remaining in the specified
     * subsequence of the given buffer array, that is,
     *
     * <blockquote><pre>
     * dsts[offset].remaining()
     *     + dsts[offset+1].remaining()
     *     + ... + dsts[offset+length-1].remaining()</pre></blockquote>
     *
     * at the moment that the read is attempted.
     *
     * <p> Suppose that a byte sequence of length <i>n</i> is read, where
     * {@code 0}&nbsp;{@code <}&nbsp;<i>n</i>&nbsp;{@code <=}&nbsp;<i>r</i>.
     * Up to the first {@code dsts[offset].remaining()} bytes of this sequence
     * are transferred into buffer {@code dsts[offset]}, up to the next
     * {@code dsts[offset+1].remaining()} bytes are transferred into buffer
     * {@code dsts[offset+1]}, and so forth, until the entire byte sequence
     * is transferred into the given buffers.  As many bytes as possible are
     * transferred into each buffer, hence the final position of each updated
     * buffer, except the last updated buffer, is guaranteed to be equal to
     * that buffer's limit. The underlying operating system may impose a limit
     * on the number of buffers that may be used in an I/O operation. Where the
     * number of buffers (with bytes remaining), exceeds this limit, then the
     * I/O operation is performed with the maximum number of buffers allowed by
     * the operating system.
     *
     * <p> If a timeout is specified and the timeout elapses before the operation
     * completes then it completes with the exception {@link
     * InterruptedByTimeoutException}. Where a timeout occurs, and the
     * implementation cannot guarantee that bytes have not been read, or will not
     * be read from the channel into the given buffers, then further attempts to
     * read from the channel will cause an unspecific runtime exception to be
     * thrown.
     *
     * @param   <A>
     *          The type of the attachment
     * @param   dsts
     *          The buffers into which bytes are to be transferred
     * @param   offset
     *          The offset within the buffer array of the first buffer into which
     *          bytes are to be transferred; must be non-negative and no larger than
     *          {@code dsts.length}
     * @param   length
     *          The maximum number of buffers to be accessed; must be non-negative
     *          and no larger than {@code dsts.length - offset}
     * @param   timeout
     *          The maximum time for the I/O operation to complete
     * @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  IndexOutOfBoundsException
     *          If the pre-conditions for the {@code offset}  and {@code length}
     *          parameter aren't met
     * @throws  IllegalArgumentException
     *          If the buffer is read-only
     * @throws  ReadPendingException
     *          If a read operation is already in progress on this channel
     * @throws  NotYetConnectedException
     *          If this channel is not yet connected
     * @throws  ShutdownChannelGroupException
     *          If the channel group has terminated
     */
    public abstract <A> void read(ByteBuffer[] dsts,
                                  int offset,
                                  int length,
                                  long timeout,
                                  TimeUnit unit,
                                  A attachment,
                                  CompletionHandler<Long,? super A> handler);

    
Writes a sequence of bytes to this channel from the given buffer.

 This method initiates an asynchronous write operation to write a sequence of bytes to this channel from the given buffer. The 
handler parameter is a completion handler that is invoked when the write operation completes (or fails). The result passed to the completion handler is the number of bytes written. 
 If a timeout is specified and the timeout elapses before the operation completes then it completes with the exception InterruptedByTimeoutException. Where a timeout occurs, and the implementation cannot guarantee that bytes have not been written, or will not be written to the channel from the given buffer, then further attempts to write to the channel will cause an unspecific runtime exception to be thrown. 
 Otherwise this method works in the same manner as the AsynchronousByteChannel.write(ByteBuffer, Object, CompletionHandler<Integer,? super Object>) method. 
Params:
  • src – 
         The buffer from which bytes are to be retrieved
  • timeout – 
         The maximum time for the I/O operation to complete
  • unit –  The time unit of the timeout argument
  • attachment –  The object to attach to the I/O operation; can be null
  • handler – 
         The handler for consuming the result
Type parameters:
  • <A> – 
         The type of the attachment
Throws:
/**
     * Writes a sequence of bytes to this channel from the given buffer.
     *
     * <p> This method initiates an asynchronous write operation to write a
     * sequence of bytes to this channel from the given buffer. The {@code
     * handler} parameter is a completion handler that is invoked when the write
     * operation completes (or fails). The result passed to the completion
     * handler is the number of bytes written.
     *
     * <p> If a timeout is specified and the timeout elapses before the operation
     * completes then it completes with the exception {@link
     * InterruptedByTimeoutException}. Where a timeout occurs, and the
     * implementation cannot guarantee that bytes have not been written, or will
     * not be written to the channel from the given buffer, then further attempts
     * to write to the channel will cause an unspecific runtime exception to be
     * thrown.
     *
     * <p> Otherwise this method works in the same manner as the {@link
     * AsynchronousByteChannel#write(ByteBuffer,Object,CompletionHandler)}
     * method.
     *
     * @param   <A>
     *          The type of the attachment
     * @param   src
     *          The buffer from which bytes are to be retrieved
     * @param   timeout
     *          The maximum time for the I/O operation to complete
     * @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  WritePendingException
     *          If a write operation is already in progress on this channel
     * @throws  NotYetConnectedException
     *          If this channel is not yet connected
     * @throws  ShutdownChannelGroupException
     *          If the channel group has terminated
     */
    public abstract <A> void write(ByteBuffer src,
                                   long timeout,
                                   TimeUnit unit,
                                   A attachment,
                                   CompletionHandler<Integer,? super A> handler);

    
Throws:
/**
     * @throws  WritePendingException          {@inheritDoc}
     * @throws  NotYetConnectedException
     *          If this channel is not yet connected
     * @throws  ShutdownChannelGroupException
     *          If the channel group has terminated
     */
    @Override
    public final <A> void write(ByteBuffer src,
                                A attachment,
                                CompletionHandler<Integer,? super A> handler)

    {
        write(src, 0L, TimeUnit.MILLISECONDS, attachment, handler);
    }

    
Throws:
/**
     * @throws  WritePendingException       {@inheritDoc}
     * @throws  NotYetConnectedException
     *          If this channel is not yet connected
     */
    @Override
    public abstract Future<Integer> write(ByteBuffer src);

    
Writes a sequence of bytes to this channel from a subsequence of the given
buffers. This operation, sometimes called a gathering write, is often useful when implementing network protocols that group data into segments consisting of one or more fixed-length headers followed by a variable-length body. The handler parameter is a completion handler that is invoked when the write operation completes (or fails). The result passed to the completion handler is the number of bytes written. 
 This method initiates a write of up to r bytes to this channel,
where r is the total number of bytes remaining in the specified
subsequence of the given buffer array, that is,

srcs[offset].remaining()
    + srcs[offset+1].remaining()
    + ... + srcs[offset+length-1].remaining()

at the moment that the write is attempted.

 Suppose that a byte sequence of length n is written, where 0 < n <= r. Up to the first srcs[offset].remaining() bytes of this sequence are written from buffer srcs[offset], up to the next srcs[offset+1].remaining() bytes are written from buffer srcs[offset+1], and so forth, until the entire byte sequence is written. As many bytes as possible are written from each buffer, hence the final position of each updated buffer, except the last updated buffer, is guaranteed to be equal to that buffer's limit. The underlying operating system may impose a limit on the number of buffers that may be used in an I/O operation. Where the number of buffers (with bytes remaining), exceeds this limit, then the I/O operation is performed with the maximum number of buffers allowed by the operating system. 
 If a timeout is specified and the timeout elapses before the operation completes then it completes with the exception InterruptedByTimeoutException. Where a timeout occurs, and the implementation cannot guarantee that bytes have not been written, or will not be written to the channel from the given buffers, then further attempts to write to the channel will cause an unspecific runtime exception to be thrown. 
Params:
  • srcs – 
         The buffers from which bytes are to be retrieved
  • offset –  The offset within the buffer array of the first buffer from which bytes are to be retrieved; must be non-negative and no larger than srcs.length
  • length –  The maximum number of buffers to be accessed; must be non-negative and no larger than srcs.length - offset
  • timeout – 
         The maximum time for the I/O operation to complete
  • unit –  The time unit of the timeout argument
  • attachment –  The object to attach to the I/O operation; can be null
  • handler – 
         The handler for consuming the result
Type parameters:
  • <A> – 
         The type of the attachment
Throws:
/**
     * Writes a sequence of bytes to this channel from a subsequence of the given
     * buffers. This operation, sometimes called a <em>gathering write</em>, is
     * often useful when implementing network protocols that group data into
     * segments consisting of one or more fixed-length headers followed by a
     * variable-length body. The {@code handler} parameter is a completion
     * handler that is invoked when the write operation completes (or fails).
     * The result passed to the completion handler is the number of bytes written.
     *
     * <p> This method initiates a write of up to <i>r</i> bytes to this channel,
     * where <i>r</i> is the total number of bytes remaining in the specified
     * subsequence of the given buffer array, that is,
     *
     * <blockquote><pre>
     * srcs[offset].remaining()
     *     + srcs[offset+1].remaining()
     *     + ... + srcs[offset+length-1].remaining()</pre></blockquote>
     *
     * at the moment that the write is attempted.
     *
     * <p> Suppose that a byte sequence of length <i>n</i> is written, where
     * {@code 0}&nbsp;{@code <}&nbsp;<i>n</i>&nbsp;{@code <=}&nbsp;<i>r</i>.
     * Up to the first {@code srcs[offset].remaining()} bytes of this sequence
     * are written from buffer {@code srcs[offset]}, up to the next
     * {@code srcs[offset+1].remaining()} bytes are written from buffer
     * {@code srcs[offset+1]}, and so forth, until the entire byte sequence is
     * written.  As many bytes as possible are written from each buffer, hence
     * the final position of each updated buffer, except the last updated
     * buffer, is guaranteed to be equal to that buffer's limit. The underlying
     * operating system may impose a limit on the number of buffers that may be
     * used in an I/O operation. Where the number of buffers (with bytes
     * remaining), exceeds this limit, then the I/O operation is performed with
     * the maximum number of buffers allowed by the operating system.
     *
     * <p> If a timeout is specified and the timeout elapses before the operation
     * completes then it completes with the exception {@link
     * InterruptedByTimeoutException}. Where a timeout occurs, and the
     * implementation cannot guarantee that bytes have not been written, or will
     * not be written to the channel from the given buffers, then further attempts
     * to write to the channel will cause an unspecific runtime exception to be
     * thrown.
     *
     * @param   <A>
     *          The type of the attachment
     * @param   srcs
     *          The buffers from which bytes are to be retrieved
     * @param   offset
     *          The offset within the buffer array of the first buffer from which
     *          bytes are to be retrieved; must be non-negative and no larger
     *          than {@code srcs.length}
     * @param   length
     *          The maximum number of buffers to be accessed; must be non-negative
     *          and no larger than {@code srcs.length - offset}
     * @param   timeout
     *          The maximum time for the I/O operation to complete
     * @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  IndexOutOfBoundsException
     *          If the pre-conditions for the {@code offset}  and {@code length}
     *          parameter aren't met
     * @throws  WritePendingException
     *          If a write operation is already in progress on this channel
     * @throws  NotYetConnectedException
     *          If this channel is not yet connected
     * @throws  ShutdownChannelGroupException
     *          If the channel group has terminated
     */
    public abstract <A> void write(ByteBuffer[] srcs,
                                   int offset,
                                   int length,
                                   long timeout,
                                   TimeUnit unit,
                                   A attachment,
                                   CompletionHandler<Long,? super A> handler);

    
{@inheritDoc}

 If there is a security manager set, its checkConnect method is called with the local address and -1 as its arguments to see if the operation is allowed. If the operation is not allowed, a SocketAddress representing the loopback address and the local port of the channel's socket is returned. 
Throws:
Returns: The SocketAddress that the socket is bound to, or the SocketAddress representing the loopback address if denied by the security manager, or null if the channel's socket is not bound
/**
     * {@inheritDoc}
     * <p>
     * If there is a security manager set, its {@code checkConnect} method is
     * called with the local address and {@code -1} as its arguments to see
     * if the operation is allowed. If the operation is not allowed,
     * a {@code SocketAddress} representing the
     * {@link java.net.InetAddress#getLoopbackAddress loopback} address and the
     * local port of the channel's socket is returned.
     *
     * @return  The {@code SocketAddress} that the socket is bound to, or the
     *          {@code SocketAddress} representing the loopback address if
     *          denied by the security manager, or {@code null} if the
     *          channel's socket is not bound
     *
     * @throws  ClosedChannelException     {@inheritDoc}
     * @throws  IOException                {@inheritDoc}
     */
    public abstract SocketAddress getLocalAddress() throws IOException;
}