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*
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* accompanied this code).
*
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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.
*
* <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 border summary="Socket options">
* <tr>
* <th>Option Name</th>
* <th>Description</th>
* </tr>
* <tr>
* <td> {@link java.net.StandardSocketOptions#SO_SNDBUF SO_SNDBUF} </td>
* <td> The size of the socket send buffer </td>
* </tr>
* <tr>
* <td> {@link java.net.StandardSocketOptions#SO_RCVBUF SO_RCVBUF} </td>
* <td> The size of the socket receive buffer </td>
* </tr>
* <tr>
* <td> {@link java.net.StandardSocketOptions#SO_KEEPALIVE SO_KEEPALIVE} </td>
* <td> Keep connection alive </td>
* </tr>
* <tr>
* <td> {@link java.net.StandardSocketOptions#SO_REUSEADDR SO_REUSEADDR} </td>
* <td> Re-use address </td>
* </tr>
* <tr>
* <td> {@link java.net.StandardSocketOptions#TCP_NODELAY TCP_NODELAY} </td>
* <td> Disable the Nagle algorithm </td>
* </tr>
* </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.
*
* @param provider
* The provider that created this channel
*/
protected AsynchronousSocketChannel(AsynchronousChannelProvider provider) {
this.provider = provider;
}
/**
* 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.
*
* <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.
*
* <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 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 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.
*
* <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.
*
* <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.
*
* <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.
*
* <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.
*
* <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.
*
* <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 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 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 <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
* <tt>0</tt> <tt><</tt> <i>n</i> <tt><=</tt> <i>r</i>.
* Up to the first <tt>dsts[offset].remaining()</tt> bytes of this sequence
* are transferred into buffer <tt>dsts[offset]</tt>, up to the next
* <tt>dsts[offset+1].remaining()</tt> bytes are transferred into buffer
* <tt>dsts[offset+1]</tt>, 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.
*
* <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 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 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 <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
* <tt>0</tt> <tt><</tt> <i>n</i> <tt><=</tt> <i>r</i>.
* Up to the first <tt>srcs[offset].remaining()</tt> bytes of this sequence
* are written from buffer <tt>srcs[offset]</tt>, up to the next
* <tt>srcs[offset+1].remaining()</tt> bytes are written from buffer
* <tt>srcs[offset+1]</tt>, 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.
*
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