- java.lang.Object
-
- java.nio.channels.spi.AbstractInterruptibleChannel
-
- java.nio.channels.SelectableChannel
-
- java.nio.channels.spi.AbstractSelectableChannel
-
- java.nio.channels.SocketChannel
-
- All Implemented Interfaces:
- Closeable, AutoCloseable, ByteChannel, Channel, GatheringByteChannel, InterruptibleChannel, NetworkChannel, ReadableByteChannel, ScatteringByteChannel, WritableByteChannel
public abstract class SocketChannel extends AbstractSelectableChannel implements ByteChannel, ScatteringByteChannel, GatheringByteChannel, NetworkChannel
A selectable channel for stream-oriented connecting sockets.A socket channel is created by invoking one of the
open
methods of this class. It is not possible to create a channel for an arbitrary, pre-existing socket. A newly-created socket channel is open but not yet connected. An attempt to invoke an I/O operation upon an unconnected channel will cause aNotYetConnectedException
to be thrown. A socket channel can be connected by invoking itsconnect
method; once connected, a socket channel remains connected until it is closed. Whether or not a socket channel is connected may be determined by invoking itsisConnected
method.Socket channels support non-blocking connection: A socket channel may be created and the process of establishing the link to the remote socket may be initiated via the
connect
method for later completion by thefinishConnect
method. Whether or not a connection operation is in progress may be determined by invoking theisConnectionPending
method.Socket channels support asynchronous shutdown, which is similar to the asynchronous close operation specified in the
Channel
class. If the input side of a socket is shut down by one thread while another thread is blocked in a read operation on the socket's channel, then the read operation in the blocked thread will complete without reading any bytes and will return -1. If the output side of a socket is shut down by one thread while another thread is blocked in a write operation on the socket's channel, then the blocked thread will receive anAsynchronousCloseException
.Socket options are configured using the
setOption
method. Socket channels support the following 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 SO_LINGER
Linger on close if data is present (when configured in blocking mode only) TCP_NODELAY
Disable the Nagle algorithm Socket channels are safe for use by multiple concurrent threads. They support concurrent reading and writing, though at most one thread may be reading and at most one thread may be writing at any given time. The
connect
andfinishConnect
methods are mutually synchronized against each other, and an attempt to initiate a read or write operation while an invocation of one of these methods is in progress will block until that invocation is complete.- Since:
- 1.4
-
-
Constructor Summary
Constructors Modifier Constructor and Description protected
SocketChannel(SelectorProvider provider)
Initializes a new instance of this class.
-
Method Summary
Methods Modifier and Type Method and Description abstract SocketChannel
bind(SocketAddress local)
Binds the channel's socket to a local address.abstract boolean
connect(SocketAddress remote)
Connects this channel's socket.abstract boolean
finishConnect()
Finishes the process of connecting a socket channel.abstract SocketAddress
getRemoteAddress()
Returns the remote address to which this channel's socket is connected.abstract boolean
isConnected()
Tells whether or not this channel's network socket is connected.abstract boolean
isConnectionPending()
Tells whether or not a connection operation is in progress on this channel.static SocketChannel
open()
Opens a socket channel.static SocketChannel
open(SocketAddress remote)
Opens a socket channel and connects it to a remote address.abstract int
read(ByteBuffer dst)
Reads a sequence of bytes from this channel into the given buffer.long
read(ByteBuffer[] dsts)
Reads a sequence of bytes from this channel into the given buffers.abstract long
read(ByteBuffer[] dsts, int offset, int length)
Reads a sequence of bytes from this channel into a subsequence of the given buffers.abstract <T> SocketChannel
setOption(SocketOption<T> name, T value)
Sets the value of a socket option.abstract SocketChannel
shutdownInput()
Shutdown the connection for reading without closing the channel.abstract SocketChannel
shutdownOutput()
Shutdown the connection for writing without closing the channel.abstract Socket
socket()
Retrieves a socket associated with this channel.int
validOps()
Returns an operation set identifying this channel's supported operations.abstract int
write(ByteBuffer src)
Writes a sequence of bytes to this channel from the given buffer.long
write(ByteBuffer[] srcs)
Writes a sequence of bytes to this channel from the given buffers.abstract long
write(ByteBuffer[] srcs, int offset, int length)
Writes a sequence of bytes to this channel from a subsequence of the given buffers.-
Methods inherited from class java.nio.channels.spi.AbstractSelectableChannel
blockingLock, configureBlocking, implCloseChannel, implCloseSelectableChannel, implConfigureBlocking, isBlocking, isRegistered, keyFor, provider, register
-
Methods inherited from class java.nio.channels.SelectableChannel
register
-
Methods inherited from class java.nio.channels.spi.AbstractInterruptibleChannel
begin, close, end, isOpen
-
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
-
Methods inherited from interface java.nio.channels.NetworkChannel
getLocalAddress, getOption, supportedOptions
-
-
-
-
Constructor Detail
-
SocketChannel
protected SocketChannel(SelectorProvider provider)
Initializes a new instance of this class.
-
-
Method Detail
-
open
public static SocketChannel open() throws IOException
Opens a socket channel.The new channel is created by invoking the
openSocketChannel
method of the system-wide defaultSelectorProvider
object.- Returns:
- A new socket channel
- Throws:
IOException
- If an I/O error occurs
-
open
public static SocketChannel open(SocketAddress remote) throws IOException
Opens a socket channel and connects it to a remote address.This convenience method works as if by invoking the
open()
method, invoking theconnect
method upon the resulting socket channel, passing it remote, and then returning that channel.- Parameters:
remote
- The remote address to which the new channel is to be connected- Throws:
AsynchronousCloseException
- If another thread closes this channel while the connect operation is in progressClosedByInterruptException
- If another thread interrupts the current thread while the connect operation is in progress, thereby closing the channel and setting the current thread's interrupt statusUnresolvedAddressException
- If the given remote address is not fully resolvedUnsupportedAddressTypeException
- If the type of the given remote address is not supportedSecurityException
- If a security manager has been installed and it does not permit access to the given remote endpointIOException
- If some other I/O error occurs
-
validOps
public final int validOps()
Returns an operation set identifying this channel's supported operations.Socket channels support connecting, reading, and writing, so this method returns (
SelectionKey.OP_CONNECT
|SelectionKey.OP_READ
|SelectionKey.OP_WRITE
).- Specified by:
validOps
in classSelectableChannel
- Returns:
- The valid-operation set
-
bind
public abstract SocketChannel bind(SocketAddress local) throws IOException
Description copied from interface:NetworkChannel
Binds the channel's socket to a local address.This method is used to establish an association between the socket and a local address. Once an association is established then the socket remains bound until the channel is closed. If the
local
parameter has the valuenull
then the socket will be bound to an address that is assigned automatically.- Specified by:
bind
in interfaceNetworkChannel
- Parameters:
local
- The address to bind the socket, ornull
to bind the socket to an automatically assigned socket address- Returns:
- This channel
- Throws:
ConnectionPendingException
- If a non-blocking connect operation is already in progress on this channelAlreadyBoundException
- If the socket is already boundUnsupportedAddressTypeException
- If the type of the given address is not supportedClosedChannelException
- If the channel is closedIOException
- If some other I/O error occurs- Since:
- 1.7
- See Also:
NetworkChannel.getLocalAddress()
-
setOption
public abstract <T> SocketChannel setOption(SocketOption<T> name, T value) throws IOException
Description copied from interface:NetworkChannel
Sets the value of a socket option.- Specified by:
setOption
in interfaceNetworkChannel
- Parameters:
name
- The socket optionvalue
- The value of the socket option. A value ofnull
may be a valid value for some socket options.- Returns:
- This channel
- Throws:
UnsupportedOperationException
- If the socket option is not supported by this channelIllegalArgumentException
- If the value is not a valid value for this socket optionClosedChannelException
- If this channel is closedIOException
- If an I/O error occurs- Since:
- 1.7
- See Also:
StandardSocketOptions
-
shutdownInput
public abstract SocketChannel shutdownInput() 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.- Returns:
- The channel
- Throws:
NotYetConnectedException
- If this channel is not yet connectedClosedChannelException
- If this channel is closedIOException
- If some other I/O error occurs- Since:
- 1.7
-
shutdownOutput
public abstract SocketChannel shutdownOutput() 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.- Returns:
- The channel
- Throws:
NotYetConnectedException
- If this channel is not yet connectedClosedChannelException
- If this channel is closedIOException
- If some other I/O error occurs- Since:
- 1.7
-
socket
public abstract Socket socket()
Retrieves a socket associated with this channel.The returned object will not declare any public methods that are not declared in the
Socket
class.- Returns:
- A socket associated with this channel
-
isConnected
public abstract boolean isConnected()
Tells whether or not this channel's network socket is connected.- Returns:
- true if, and only if, this channel's network socket
is
open
and connected
-
isConnectionPending
public abstract boolean isConnectionPending()
Tells whether or not a connection operation is in progress on this channel.- Returns:
- true if, and only if, a connection operation has been
initiated on this channel but not yet completed by invoking the
finishConnect
method
-
connect
public abstract boolean connect(SocketAddress remote) throws IOException
Connects this channel's socket.If this channel is in non-blocking mode then an invocation of this method initiates a non-blocking connection operation. If the connection is established immediately, as can happen with a local connection, then this method returns true. Otherwise this method returns false and the connection operation must later be completed by invoking the
finishConnect
method.If this channel is in blocking mode then an invocation of this method will block until the connection is established or an I/O error occurs.
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 itscheckConnect
method permits connecting to the address and port number of the given remote endpoint.This method may be invoked at any time. If a read or write operation upon this channel is invoked while an invocation of this method is in progress then that operation will first block until this invocation is complete. If a connection attempt is initiated but fails, that is, if an invocation of this method throws a checked exception, then the channel will be closed.
- Parameters:
remote
- The remote address to which this channel is to be connected- Returns:
- true if a connection was established, false if this channel is in non-blocking mode and the connection operation is in progress
- Throws:
AlreadyConnectedException
- If this channel is already connectedConnectionPendingException
- If a non-blocking connection operation is already in progress on this channelClosedChannelException
- If this channel is closedAsynchronousCloseException
- If another thread closes this channel while the connect operation is in progressClosedByInterruptException
- If another thread interrupts the current thread while the connect operation is in progress, thereby closing the channel and setting the current thread's interrupt statusUnresolvedAddressException
- If the given remote address is not fully resolvedUnsupportedAddressTypeException
- If the type of the given remote address is not supportedSecurityException
- If a security manager has been installed and it does not permit access to the given remote endpointIOException
- If some other I/O error occurs
-
finishConnect
public abstract boolean finishConnect() throws IOException
Finishes the process of connecting a socket channel.A non-blocking connection operation is initiated by placing a socket channel in non-blocking mode and then invoking its
connect
method. Once the connection is established, or the attempt has failed, the socket channel will become connectable and this method may be invoked to complete the connection sequence. If the connection operation failed then invoking this method will cause an appropriateIOException
to be thrown.If this channel is already connected then this method will not block and will immediately return true. If this channel is in non-blocking mode then this method will return false if the connection process is not yet complete. If this channel is in blocking mode then this method will block until the connection either completes or fails, and will always either return true or throw a checked exception describing the failure.
This method may be invoked at any time. If a read or write operation upon this channel is invoked while an invocation of this method is in progress then that operation will first block until this invocation is complete. If a connection attempt fails, that is, if an invocation of this method throws a checked exception, then the channel will be closed.
- Returns:
- true if, and only if, this channel's socket is now connected
- Throws:
NoConnectionPendingException
- If this channel is not connected and a connection operation has not been initiatedClosedChannelException
- If this channel is closedAsynchronousCloseException
- If another thread closes this channel while the connect operation is in progressClosedByInterruptException
- If another thread interrupts the current thread while the connect operation is in progress, thereby closing the channel and setting the current thread's interrupt statusIOException
- If some other I/O error occurs
-
getRemoteAddress
public abstract SocketAddress getRemoteAddress() throws IOException
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
.- Returns:
- The remote address;
null
if the channel's socket is not connected - Throws:
ClosedChannelException
- If the channel is closedIOException
- If an I/O error occurs- Since:
- 1.7
-
read
public abstract int read(ByteBuffer dst) throws IOException
Description copied from interface:ReadableByteChannel
Reads a sequence of bytes from this channel into the given buffer.An attempt is made to read up to r bytes from the channel, where r is the number of bytes remaining in the buffer, that is, dst.remaining(), at the moment this method is invoked.
Suppose that a byte sequence of length n is read, where 0 <= n <= r. This byte sequence will be transferred into the buffer so that the first byte in the sequence is at index p and the last byte is at index p + n - 1, where p is the buffer's position at the moment this method is invoked. Upon return the buffer's position will be equal to p + n; its limit will not have changed.
A read operation might not fill the buffer, and in fact it might not read any bytes at all. Whether or not it does so depends upon the nature and state of the channel. A socket channel in non-blocking mode, for example, cannot read any more bytes than are immediately available from the socket's input buffer; similarly, a file channel cannot read any more bytes than remain in the file. It is guaranteed, however, that if a channel is in blocking mode and there is at least one byte remaining in the buffer then this method will block until at least one byte is read.
This method may be invoked at any time. If another thread has already initiated a read operation upon this channel, however, then an invocation of this method will block until the first operation is complete.
- Specified by:
read
in interfaceReadableByteChannel
- Parameters:
dst
- The buffer into which bytes are to be transferred- Returns:
- The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream
- Throws:
NotYetConnectedException
- If this channel is not yet connectedClosedChannelException
- If this channel is closedAsynchronousCloseException
- If another thread closes this channel while the read operation is in progressClosedByInterruptException
- If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt statusIOException
- If some other I/O error occurs
-
read
public abstract long read(ByteBuffer[] dsts, int offset, int length) throws IOException
Description copied from interface:ScatteringByteChannel
Reads a sequence of bytes from this channel into a subsequence of the given buffers.An invocation of this method attempts to read up to r bytes from this channel, where r is the total number of bytes remaining the specified subsequence of the given buffer array, that is,
at the moment that this method is invoked.dsts[offset].remaining() + dsts[offset+1].remaining() + ... + dsts[offset+length-1].remaining()
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.
This method may be invoked at any time. If another thread has already initiated a read operation upon this channel, however, then an invocation of this method will block until the first operation is complete.
- Specified by:
read
in interfaceScatteringByteChannel
- Parameters:
dsts
- The buffers into which bytes are to be transferredoffset
- 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.lengthlength
- The maximum number of buffers to be accessed; must be non-negative and no larger than dsts.length - offset- Returns:
- The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream
- Throws:
NotYetConnectedException
- If this channel is not yet connectedClosedChannelException
- If this channel is closedAsynchronousCloseException
- If another thread closes this channel while the read operation is in progressClosedByInterruptException
- If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt statusIOException
- If some other I/O error occurs
-
read
public final long read(ByteBuffer[] dsts) throws IOException
Description copied from interface:ScatteringByteChannel
Reads a sequence of bytes from this channel into the given buffers.An invocation of this method of the form c.read(dsts) behaves in exactly the same manner as the invocation
c.read(dsts, 0, dsts.length);
- Specified by:
read
in interfaceScatteringByteChannel
- Parameters:
dsts
- The buffers into which bytes are to be transferred- Returns:
- The number of bytes read, possibly zero, or -1 if the channel has reached end-of-stream
- Throws:
NotYetConnectedException
- If this channel is not yet connectedClosedChannelException
- If this channel is closedAsynchronousCloseException
- If another thread closes this channel while the read operation is in progressClosedByInterruptException
- If another thread interrupts the current thread while the read operation is in progress, thereby closing the channel and setting the current thread's interrupt statusIOException
- If some other I/O error occurs
-
write
public abstract int write(ByteBuffer src) throws IOException
Description copied from interface:WritableByteChannel
Writes a sequence of bytes to this channel from the given buffer.An attempt is made to write up to r bytes to the channel, where r is the number of bytes remaining in the buffer, that is, src.remaining(), at the moment this method is invoked.
Suppose that a byte sequence of length n is written, where 0 <= n <= r. This byte sequence will be transferred from the buffer starting at index p, where p is the buffer's position at the moment this method is invoked; the index of the last byte written will be p + n - 1. Upon return the buffer's position will be equal to p + n; its limit will not have changed.
Unless otherwise specified, a write operation will return only after writing all of the r requested bytes. Some types of channels, depending upon their state, may write only some of the bytes or possibly none at all. A socket channel in non-blocking mode, for example, cannot write any more bytes than are free in the socket's output buffer.
This method may be invoked at any time. If another thread has already initiated a write operation upon this channel, however, then an invocation of this method will block until the first operation is complete.
- Specified by:
write
in interfaceWritableByteChannel
- Parameters:
src
- The buffer from which bytes are to be retrieved- Returns:
- The number of bytes written, possibly zero
- Throws:
NotYetConnectedException
- If this channel is not yet connectedClosedChannelException
- If this channel is closedAsynchronousCloseException
- If another thread closes this channel while the write operation is in progressClosedByInterruptException
- If another thread interrupts the current thread while the write operation is in progress, thereby closing the channel and setting the current thread's interrupt statusIOException
- If some other I/O error occurs
-
write
public abstract long write(ByteBuffer[] srcs, int offset, int length) throws IOException
Description copied from interface:GatheringByteChannel
Writes a sequence of bytes to this channel from a subsequence of the given buffers.An attempt is made to write 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,
at the moment that this method is invoked.srcs[offset].remaining() + srcs[offset+1].remaining() + ... + srcs[offset+length-1].remaining()
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.
Unless otherwise specified, a write operation will return only after writing all of the r requested bytes. Some types of channels, depending upon their state, may write only some of the bytes or possibly none at all. A socket channel in non-blocking mode, for example, cannot write any more bytes than are free in the socket's output buffer.
This method may be invoked at any time. If another thread has already initiated a write operation upon this channel, however, then an invocation of this method will block until the first operation is complete.
- Specified by:
write
in interfaceGatheringByteChannel
- Parameters:
srcs
- The buffers from which bytes are to be retrievedoffset
- 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.lengthlength
- The maximum number of buffers to be accessed; must be non-negative and no larger than srcs.length - offset- Returns:
- The number of bytes written, possibly zero
- Throws:
NotYetConnectedException
- If this channel is not yet connectedClosedChannelException
- If this channel is closedAsynchronousCloseException
- If another thread closes this channel while the write operation is in progressClosedByInterruptException
- If another thread interrupts the current thread while the write operation is in progress, thereby closing the channel and setting the current thread's interrupt statusIOException
- If some other I/O error occurs
-
write
public final long write(ByteBuffer[] srcs) throws IOException
Description copied from interface:GatheringByteChannel
Writes a sequence of bytes to this channel from the given buffers.An invocation of this method of the form c.write(srcs) behaves in exactly the same manner as the invocation
c.write(srcs, 0, srcs.length);
- Specified by:
write
in interfaceGatheringByteChannel
- Parameters:
srcs
- The buffers from which bytes are to be retrieved- Returns:
- The number of bytes written, possibly zero
- Throws:
NotYetConnectedException
- If this channel is not yet connectedClosedChannelException
- If this channel is closedAsynchronousCloseException
- If another thread closes this channel while the write operation is in progressClosedByInterruptException
- If another thread interrupts the current thread while the write operation is in progress, thereby closing the channel and setting the current thread's interrupt statusIOException
- If some other I/O error occurs
-
-
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Dokument erstellt 11/06/2005, zuletzt geändert 04/03/2020
Quelle des gedruckten Dokuments:https://www.gaudry.be/de/java-api-rf-java/nio/channels/SocketChannel.html
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