SocketImpl

public abstract class SocketImpl extends Object
implements SocketOptions

The abstract class SocketImpl is a common superclass of all classes that actually implement sockets. It is used to create both client and server sockets.

A "plain" socket implements these methods exactly as described, without attempting to go through a firewall or proxy.

Inherited Constant Summary

Field Summary

protected InetAddress address The IP address of the remote end of this socket.
protected FileDescriptor fd The file descriptor object for this socket.
protected int localport The local port number to which this socket is connected.
protected int port The port number on the remote host to which this socket is connected.

Public Constructor Summary

Public Method Summary

String
toString()
Returns the address and port of this socket as a String.

Protected Method Summary

abstract void
accept(SocketImpl s)
Accepts a connection.
abstract int
available()
Returns the number of bytes that can be read from this socket without blocking.
abstract void
bind(InetAddress host, int port)
Binds this socket to the specified local IP address and port number.
abstract void
close()
Closes this socket.
abstract void
connect(InetAddress address, int port)
Connects this socket to the specified port number on the specified host.
abstract void
connect(SocketAddress address, int timeout)
Connects this socket to the specified port number on the specified host.
abstract void
connect(String host, int port)
Connects this socket to the specified port on the named host.
abstract void
create(boolean stream)
Creates either a stream or a datagram socket.
FileDescriptor
getFileDescriptor()
Returns the value of this socket's fd field.
InetAddress
getInetAddress()
Returns the value of this socket's address field.
abstract InputStream
getInputStream()
Returns an input stream for this socket.
int
getLocalPort()
Returns the value of this socket's localport field.
abstract OutputStream
getOutputStream()
Returns an output stream for this socket.
int
getPort()
Returns the value of this socket's port field.
abstract void
listen(int backlog)
Sets the maximum queue length for incoming connection indications (a request to connect) to the count argument.
abstract void
sendUrgentData(int data)
Send one byte of urgent data on the socket.
void
setPerformancePreferences(int connectionTime, int latency, int bandwidth)
Sets performance preferences for this socket.
void
shutdownInput()
Places the input stream for this socket at "end of stream".
void
shutdownOutput()
Disables the output stream for this socket.
boolean
supportsUrgentData()
Returns whether or not this SocketImpl supports sending urgent data.

Inherited Method Summary

Fields

protected InetAddress address

The IP address of the remote end of this socket.

protected FileDescriptor fd

The file descriptor object for this socket.

protected int localport

The local port number to which this socket is connected.

protected int port

The port number on the remote host to which this socket is connected.

Public Constructors

public SocketImpl ()

Public Methods

public String toString ()

Returns the address and port of this socket as a String.

Returns
  • a string representation of this socket.

Protected Methods

protected abstract void accept (SocketImpl s)

Accepts a connection.

Parameters
s the accepted connection.
Throws
IOException if an I/O error occurs when accepting the connection.

protected abstract int available ()

Returns the number of bytes that can be read from this socket without blocking.

Returns
  • the number of bytes that can be read from this socket without blocking.
Throws
IOException if an I/O error occurs when determining the number of bytes available.

protected abstract void bind (InetAddress host, int port)

Binds this socket to the specified local IP address and port number.

Parameters
host an IP address that belongs to a local interface.
port the port number.
Throws
IOException if an I/O error occurs when binding this socket.

protected abstract void close ()

Closes this socket.

Throws
IOException if an I/O error occurs when closing this socket.

protected abstract void connect (InetAddress address, int port)

Connects this socket to the specified port number on the specified host.

Parameters
address the IP address of the remote host.
port the port number.
Throws
IOException if an I/O error occurs when attempting a connection.

protected abstract void connect (SocketAddress address, int timeout)

Connects this socket to the specified port number on the specified host. A timeout of zero is interpreted as an infinite timeout. The connection will then block until established or an error occurs.

Parameters
address the Socket address of the remote host.
timeout the timeout value, in milliseconds, or zero for no timeout.
Throws
IOException if an I/O error occurs when attempting a connection.

protected abstract void connect (String host, int port)

Connects this socket to the specified port on the named host.

Parameters
host the name of the remote host.
port the port number.
Throws
IOException if an I/O error occurs when connecting to the remote host.

protected abstract void create (boolean stream)

Creates either a stream or a datagram socket.

Parameters
stream if true, create a stream socket; otherwise, create a datagram socket.
Throws
IOException if an I/O error occurs while creating the socket.

protected FileDescriptor getFileDescriptor ()

Returns the value of this socket's fd field.

Returns
  • the value of this socket's fd field.
See Also

protected InetAddress getInetAddress ()

Returns the value of this socket's address field.

Returns
  • the value of this socket's address field.
See Also

protected abstract InputStream getInputStream ()

Returns an input stream for this socket.

Returns
  • a stream for reading from this socket.
Throws
IOException if an I/O error occurs when creating the input stream.

protected int getLocalPort ()

Returns the value of this socket's localport field.

Returns
  • the value of this socket's localport field.
See Also

protected abstract OutputStream getOutputStream ()

Returns an output stream for this socket.

Returns
  • an output stream for writing to this socket.
Throws
IOException if an I/O error occurs when creating the output stream.

protected int getPort ()

Returns the value of this socket's port field.

Returns
  • the value of this socket's port field.
See Also

protected abstract void listen (int backlog)

Sets the maximum queue length for incoming connection indications (a request to connect) to the count argument. If a connection indication arrives when the queue is full, the connection is refused.

Parameters
backlog the maximum length of the queue.
Throws
IOException if an I/O error occurs when creating the queue.

protected abstract void sendUrgentData (int data)

Send one byte of urgent data on the socket. The byte to be sent is the low eight bits of the parameter

Parameters
data The byte of data to send
Throws
IOException if there is an error sending the data.

protected void setPerformancePreferences (int connectionTime, int latency, int bandwidth)

Sets performance preferences for this socket.

Sockets use the TCP/IP protocol by default. Some implementations may offer alternative protocols which have different performance characteristics than TCP/IP. This method allows the application to express its own preferences as to how these tradeoffs should be made when the implementation chooses from the available protocols.

Performance preferences are described by three integers whose values indicate the relative importance of short connection time, low latency, and high bandwidth. The absolute values of the integers are irrelevant; in order to choose a protocol the values are simply compared, with larger values indicating stronger preferences. Negative values represent a lower priority than positive values. If the application prefers short connection time over both low latency and high bandwidth, for example, then it could invoke this method with the values (1, 0, 0). If the application prefers high bandwidth above low latency, and low latency above short connection time, then it could invoke this method with the values (0, 1, 2). By default, this method does nothing, unless it is overridden in a a sub-class.

Parameters
connectionTime An int expressing the relative importance of a short connection time
latency An int expressing the relative importance of low latency
bandwidth An int expressing the relative importance of high bandwidth

protected void shutdownInput ()

Places the input stream for this socket at "end of stream". Any data sent to this 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
IOException if an I/O error occurs when shutting down this socket.

protected void shutdownOutput ()

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

protected boolean supportsUrgentData ()

Returns whether or not this SocketImpl supports sending urgent data. By default, false is returned unless the method is overridden in a sub-class

Returns
  • true if urgent data supported
See Also