p2ps.imp.net
Interface Socket

All Known Subinterfaces:

SSLSocket

All Known Implementing Classes:

InetSocket, InetSSLSocket

public interface Socket

An interface to an underlying socket. This interface has many of the same methods as java.net.Socket, but allows different socket implementations to be plugged in.

Version:

$Revision: 295 $

Author:

Ian Wang

Method Summary

void	bind(java.net.SocketAddress bindpoint) Binds the socket to a local address.
void	close() Closes this socket.
void	connect(java.net.SocketAddress endpoint) Connects this socket to the server.
void	connect(java.net.SocketAddress endpoint, int timeout) Connects this socket to the server with a specified timeout value.
java.io.InputStream	getInputStream() Returns an input stream for this socket.
int	getLocalPort() Returns the local port to which this socket is bound.
java.net.SocketAddress	getLocalSocketAddress() Returns the address of the endpoint this socket is bound to, or null if it is not bound yet.
java.io.OutputStream	getOutputStream() Returns an output stream for this socket.
int	getPort() Returns the remote port to which this socket is connected.
int	getReceiveBufferSize() Gets the value of the SO_RCVBUF option for this Socket, that is the buffer size used by the platform for input on this Socket.
java.net.SocketAddress	getRemoteSocketAddress() Returns the address of the endpoint this socket is connected to, or null if it is unconnected.
boolean	getReuseAddress() Tests if SO_REUSEADDR is enabled.
int	getSendBufferSize() Get value of the SO_SNDBUF option for this Socket, that is the buffer size used by the platform for output on this Socket.
int	getSoTimeout() Returns setting for SO_TIMEOUT.
boolean	isBound() Returns the binding state of the socket.
boolean	isClosed() Returns the closed state of the socket.
boolean	isConnected() Returns the connection state of the socket.
boolean	isInputShutdown() Returns whether the read-half of the socket connection is closed.
boolean	isOutputShutdown() Returns whether the write-half of the socket connection is closed.
void	setReceiveBufferSize(int size) Sets the SO_RCVBUF option to the specified value for this Socket.
void	setReuseAddress(boolean on) Enable/disable the SO_REUSEADDR socket option.
void	setSendBufferSize(int size) Sets the SO_SNDBUF option to the specified value for this Socket.
void	setSoTimeout(int timeout) Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds.
void	shutdownInput() Places the input stream for this socket at "end of stream".
void	shutdownOutput() Disables the output stream for this socket.

Method Detail

bind

public void bind(java.net.SocketAddress bindpoint)
          throws java.io.IOException

Binds the socket to a local address.

If the address is null, then the system will pick up an ephemeral port and a valid local address to bind the socket.

Parameters:

bindpoint - the SocketAddress to bind to

Throws:

java.lang.IllegalArgumentException - if bindpoint is a SocketAddress subclass not supported by this socket

java.io.IOException - if the bind operation fails, or if the socket is already bound.

Since:

1.4

See Also:

isBound()

isBound

public boolean isBound()

Returns the binding state of the socket.

Returns:

true if the socket successfuly bound to an address

Since:

1.4

See Also:

bind(java.net.SocketAddress)

connect

public void connect(java.net.SocketAddress endpoint)
             throws java.io.IOException

Connects this socket to the server.

Parameters:

endpoint - the SocketAddress

Throws:

java.nio.channels.IllegalBlockingModeException - if this socket has an associated channel, and the channel is in non-blocking mode

java.lang.IllegalArgumentException - if endpoint is null or is a SocketAddress subclass not supported by this socket

java.io.IOException - if an error occurs during the connection

Since:

1.4

connect

public void connect(java.net.SocketAddress endpoint,
                    int timeout)
             throws java.io.IOException

Connects this socket to the server with a specified timeout value. A timeout of zero is interpreted as an infinite timeout. The connection will then block until established or an error occurs.

Parameters:

endpoint - the SocketAddress

timeout - the timeout value to be used in milliseconds.

Throws:

java.nio.channels.IllegalBlockingModeException - if this socket has an associated channel, and the channel is in non-blocking mode

java.lang.IllegalArgumentException - if endpoint is null or is a SocketAddress subclass not supported by this socket

java.io.IOException - if an error occurs during the connection

java.net.SocketTimeoutException - if timeout expires before connecting

Since:

1.4

isConnected

public boolean isConnected()

Returns the connection state of the socket.

Returns:

true if the socket successfuly connected to a server

Since:

1.4

close

public void close()
           throws java.io.IOException

Closes this socket.

Any thread currently blocked in an I/O operation upon this socket will throw a SocketException.

Once a socket has been closed, it is not available for further networking use (i.e. can't be reconnected or rebound). A new socket needs to be created.

If this socket has an associated channel then the channel is closed as well.

Throws:

java.io.IOException - if an I/O error occurs when closing this socket.

See Also:

isClosed()

isClosed

public boolean isClosed()

Returns the closed state of the socket.

Returns:

true if the socket has been closed

Since:

1.4

See Also:

close()

getInputStream

public java.io.InputStream getInputStream()
                                   throws java.io.IOException

Returns an input stream for this socket.

If this socket has an associated channel then the resulting input stream delegates all of its operations to the channel. If the channel is in non-blocking mode then the input stream's read operations will throw an java.nio.channels.IllegalBlockingModeException.

Under abnormal conditions the underlying connection may be broken by the remote host or the network software (for example a connection reset in the case of TCP connections). When a broken connection is detected by the network software the following applies to the returned input stream :-

• The network software may discard bytes that are buffered by the socket. Bytes that aren't discarded by the network software can be read using read.

• If there are no bytes buffered on the socket, or all buffered bytes have been consumed by read, then all subsequent calls to read will throw an IOException.

• If there are no bytes buffered on the socket, and the socket has not been closed using close, then available will return 0.

Returns:

an input stream for reading bytes from this socket.

Throws:

java.io.IOException - if an I/O error occurs when creating the input stream, the socket is closed, the socket is not connected, or the socket input has been shutdown using shutdownInput()

getOutputStream

public java.io.OutputStream getOutputStream()
                                     throws java.io.IOException

Returns an output stream for this socket.

If this socket has an associated channel then the resulting output stream delegates all of its operations to the channel. If the channel is in non-blocking mode then the output stream's write operations will throw an java.nio.channels.IllegalBlockingModeException.

Returns:

an output stream for writing bytes to this socket.

Throws:

java.io.IOException - if an I/O error occurs when creating the output stream or if the socket is not connected.

getLocalSocketAddress

public java.net.SocketAddress getLocalSocketAddress()

Returns the address of the endpoint this socket is bound to, or null if it is not bound yet.

Returns:

a SocketAddress representing the local endpoint of this socket, or null if it is not bound yet.

Since:

1.4

See Also:

getLocalPort(), bind(java.net.SocketAddress)

getLocalPort

public int getLocalPort()

Returns the local port to which this socket is bound.

Returns:

the local port number to which this socket is bound or -1 if the socket is not bound yet.

getPort

public int getPort()

Returns the remote port to which this socket is connected.

Returns:

the remote port number to which this socket is connected, or 0 if the socket is not connected yet.

getRemoteSocketAddress

public java.net.SocketAddress getRemoteSocketAddress()

Returns the address of the endpoint this socket is connected to, or null if it is unconnected.

Returns:

a SocketAddress reprensenting the remote endpoint of this socket, or null if it is not connected yet.

Since:

1.4

See Also:

getPort(), connect(java.net.SocketAddress, int), connect(java.net.SocketAddress)

getSoTimeout

public int getSoTimeout()
                 throws java.net.SocketException

Returns setting for SO_TIMEOUT. 0 returns implies that the option is disabled (i.e., timeout of infinity).

Returns:

the setting for SO_TIMEOUT

Throws:

java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.

Since:

JDK1.1

See Also:

setSoTimeout(int)

setSoTimeout

public void setSoTimeout(int timeout)
                  throws java.net.SocketException

Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds. With this option set to a non-zero timeout, a read() call on the InputStream associated with this Socket will block for only this amount of time. If the timeout expires, a java.net.SocketTimeoutException is raised, though the Socket is still valid. The option must be enabled prior to entering the blocking operation to have effect. The timeout must be > 0. A timeout of zero is interpreted as an infinite timeout.

Parameters:

timeout - the specified timeout, in milliseconds.

Throws:

java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.

Since:

JDK 1.1

See Also:

getSoTimeout()

getSendBufferSize

public int getSendBufferSize()
                      throws java.net.SocketException

Get value of the SO_SNDBUF option for this Socket, that is the buffer size used by the platform for output on this Socket.

Returns:

the value of the SO_SNDBUF option for this Socket.

Throws:

java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.

Since:

1.2

See Also:

setSendBufferSize(int)

setSendBufferSize

public void setSendBufferSize(int size)
                       throws java.net.SocketException

Sets the SO_SNDBUF option to the specified value for this Socket. The SO_SNDBUF option is used by the platform's networking code as a hint for the size to set the underlying network I/O buffers.

Because SO_SNDBUF is a hint, applications that want to verify what size the buffers were set to should call getSendBufferSize().

Parameters:

size - the size to which to set the send buffer size. This value must be greater than 0.

Throws:

java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.

java.lang.IllegalArgumentException - if the value is 0 or is negative.

Since:

1.2

See Also:

getSendBufferSize()

getReceiveBufferSize

public int getReceiveBufferSize()
                         throws java.net.SocketException

Gets the value of the SO_RCVBUF option for this Socket, that is the buffer size used by the platform for input on this Socket.

Returns:

the value of the SO_RCVBUF option for this Socket.

Throws:

java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.

Since:

1.2

See Also:

setReceiveBufferSize(int)

setReceiveBufferSize

public void setReceiveBufferSize(int size)
                          throws java.net.SocketException

Sets the SO_RCVBUF option to the specified value for this Socket. The SO_RCVBUF option is used by the platform's networking code as a hint for the size to set the underlying network I/O buffers.

Increasing the receive buffer size can increase the performance of network I/O for high-volume connection, while decreasing it can help reduce the backlog of incoming data.

Because SO_RCVBUF is a hint, applications that want to verify what size the buffers were set to should call getReceiveBufferSize().

The value of SO_RCVBUF is also used to set the TCP receive window that is advertized to the remote peer. Generally, the window size can be modified at any time when a socket is connected. However, if a receive window larger than 64K is required then this must be requested before the socket is connected to the remote peer. There are two cases to be aware of:

1. For sockets accepted from a ServerSocket, this must be done by calling ServerSocket.setReceiveBufferSize(int) before the ServerSocket is bound to a local address.

2. For client sockets, setReceiveBufferSize() must be called before connecting the socket to its remote peer.

Parameters:

size - the size to which to set the receive buffer size. This value must be greater than 0.

Throws:

java.lang.IllegalArgumentException - if the value is 0 or is negative.

java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.

Since:

1.2

See Also:

getReceiveBufferSize(), ServerSocket.setReceiveBufferSize(int)

getReuseAddress

public boolean getReuseAddress()
                        throws java.net.SocketException

Tests if SO_REUSEADDR is enabled.

Returns:

a boolean indicating whether or not SO_REUSEADDR is enabled.

Throws:

java.net.SocketException - if there is an error in the underlying protocol, such as a TCP error.

Since:

1.4

See Also:

setReuseAddress(boolean)

setReuseAddress

public void setReuseAddress(boolean on)
                     throws java.net.SocketException

Enable/disable the SO_REUSEADDR socket option.

When a TCP connection is closed the connection may remain in a timeout state for a period of time after the connection is closed (typically known as the TIME_WAIT state or 2MSL wait state). For applications using a well known socket address or port it may not be possible to bind a socket to the required SocketAddress if there is a connection in the timeout state involving the socket address or port.

Enabling SO_REUSEADDR prior to binding the socket using bind(java.net.SocketAddress) allows the socket to be bound even though a previous connection is in a timeout state.

When a Socket is created the initial setting of SO_REUSEADDR is disabled.

The behaviour when SO_REUSEADDR is enabled or disabled after a socket is bound (See isBound()) is not defined.

Parameters:

on - whether to enable or disable the socket option

Throws:

java.net.SocketException - if an error occurs enabling or disabling the SO_RESUEADDR socket option, or the socket is closed.

Since:

1.4

See Also:

getReuseAddress(), bind(java.net.SocketAddress), isClosed(), isBound()

shutdownInput

public void shutdownInput()
                   throws java.io.IOException

Places the input stream for this socket at "end of stream". Any data sent to the input stream side of the socket is acknowledged and then silently discarded.

If you read from a socket input stream after invoking shutdownInput() on the socket, the stream will return EOF.

Throws:

java.io.IOException - if an I/O error occurs when shutting down this socket.

Since:

1.3

See Also:

Socket.shutdownOutput(), Socket.close(), Socket.setSoLinger(boolean, int), isInputShutdown()

isInputShutdown

public boolean isInputShutdown()

Returns whether the read-half of the socket connection is closed.

Returns:

true if the input of the socket has been shutdown

Since:

1.4

See Also:

shutdownInput()

shutdownOutput

public void shutdownOutput()
                    throws java.io.IOException

Disables the output stream for this socket. For a TCP socket, any previously written data will be sent followed by TCP's normal connection termination sequence.

If you write to a socket output stream after invoking shutdownOutput() on the socket, the stream will throw an IOException.

Throws:

java.io.IOException - if an I/O error occurs when shutting down this socket.

Since:

1.3

See Also:

Socket.shutdownInput(), Socket.close(), Socket.setSoLinger(boolean, int), isOutputShutdown()

isOutputShutdown

public boolean isOutputShutdown()

Returns whether the write-half of the socket connection is closed.

Returns:

true if the output of the socket has been shutdown

Since:

1.4

See Also:

shutdownOutput()