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.
protected FileDescriptor fd
The file descriptor object for this socket.
protected InetAddress address
The IP address of the remote end of this socket.
protected int port
The port number on the remote host to which this socket is connected.
protected int localport
The local port number to which this socket is connected.
public SocketImpl()
protected abstract void create(boolean stream)
throws IOException Creates either a stream or a datagram socket.
stream - if true, create a stream socket; otherwise, create a datagram socket.IOException - if an I/O error occurs while creating the socket.protected abstract void connect(String host,
int port)
throws IOException Connects this socket to the specified port on the named host.
host - the name of the remote host.port - the port number.IOException - if an I/O error occurs when connecting to the remote host.protected abstract void connect(InetAddress address,
int port)
throws IOException Connects this socket to the specified port number on the specified host.
address - the IP address of the remote host.port - the port number.IOException - if an I/O error occurs when attempting a connection.protected abstract void connect(SocketAddress address,
int timeout)
throws IOException 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.
address - the Socket address of the remote host.timeout - the timeout value, in milliseconds, or zero for no timeout.IOException - if an I/O error occurs when attempting a connection.protected abstract void bind(InetAddress host,
int port)
throws IOException Binds this socket to the specified local IP address and port number.
host - an IP address that belongs to a local interface.port - the port number.IOException - if an I/O error occurs when binding this socket.protected abstract void listen(int backlog)
throws IOException 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.
backlog - the maximum length of the queue.IOException - if an I/O error occurs when creating the queue.protected abstract void accept(SocketImpl s)
throws IOException Accepts a connection.
s - the accepted connection.IOException - if an I/O error occurs when accepting the connection.protected abstract InputStream getInputStream()
throws IOException Returns an input stream for this socket.
IOException - if an I/O error occurs when creating the input stream.protected abstract OutputStream getOutputStream()
throws IOException Returns an output stream for this socket.
IOException - if an I/O error occurs when creating the output stream.protected abstract int available()
throws IOException Returns the number of bytes that can be read from this socket without blocking.
IOException - if an I/O error occurs when determining the number of bytes available.protected abstract void close()
throws IOException Closes this socket.
IOException - if an I/O error occurs when closing this socket.protected void shutdownInput()
throws IOException 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 this method on the socket, the stream's available method will return 0, and its read methods will return -1 (end of stream).
IOException - if an I/O error occurs when shutting down this socket.Socket.shutdownOutput(), Socket.close(), Socket.setSoLinger(boolean, int)
protected void shutdownOutput()
throws 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.
IOException - if an I/O error occurs when shutting down this socket.Socket.shutdownInput(), Socket.close(), Socket.setSoLinger(boolean, int)
protected FileDescriptor getFileDescriptor()
Returns the value of this socket's fd field.
fd field.fdprotected InetAddress getInetAddress()
Returns the value of this socket's address field.
address field.addressprotected int getPort()
Returns the value of this socket's port field.
port field.portprotected 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
addressprotected abstract void sendUrgentData(int data)
throws IOException Send one byte of urgent data on the socket. The byte to be sent is the low eight bits of the parameter
data - The byte of data to sendIOException - if there is an error sending the data.protected int getLocalPort()
Returns the value of this socket's localport field.
localport field.localportpublic String toString()
Returns the address and port of this socket as a String.
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.
connectionTime - An int expressing the relative importance of a short connection timelatency - An int expressing the relative importance of low latencybandwidth - An int expressing the relative importance of high bandwidth
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