Module java.base
Package java.net

Class SocketImpl

  • All Implemented Interfaces:
    SocketOptions


    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.

    Since:
    1.0
    • Field Detail

      • fd

        protected FileDescriptor fd
        The file descriptor object for this socket.
      • address

        protected InetAddress address
        The IP address of the remote end of this socket.
      • port

        protected int port
        The port number on the remote host to which this socket is connected.
      • localport

        protected int localport
        The local port number to which this socket is connected.
    • Constructor Detail

      • SocketImpl

        public SocketImpl​()
    • Method Detail

      • create

        protected abstract void create​(boolean stream)
                                throws IOException
        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.
      • connect

        protected abstract void connect​(String host,
                                        int port)
                                 throws IOException
        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.
      • connect

        protected abstract void connect​(InetAddress address,
                                        int port)
                                 throws IOException
        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.
      • connect

        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.
        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.
        Since:
        1.4
      • bind

        protected abstract void bind​(InetAddress host,
                                     int port)
                              throws IOException
        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.
      • listen

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

        protected abstract void accept​(SocketImpl s)
                                throws IOException
        Accepts a connection.
        Parameters:
        s - the accepted connection.
        Throws:
        IOException - if an I/O error occurs when accepting the connection.
      • getInputStream

        protected abstract InputStream getInputStream​()
                                               throws IOException
        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.
      • getOutputStream

        protected abstract OutputStream getOutputStream​()
                                                 throws IOException
        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.
      • available

        protected abstract int available​()
                                  throws IOException
        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.
      • close

        protected abstract void close​()
                               throws IOException
        Closes this socket.
        Throws:
        IOException - if an I/O error occurs when closing this socket.
      • shutdownInput

        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).
        Throws:
        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)
      • shutdownOutput

        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.
        Throws:
        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)
      • getFileDescriptor

        protected FileDescriptor getFileDescriptor​()
        Returns the value of this socket's fd field.
        Returns:
        the value of this socket's fd field.
        See Also:
        fd
      • getInetAddress

        protected InetAddress getInetAddress​()
        Returns the value of this socket's address field.
        Returns:
        the value of this socket's address field.
        See Also:
        address
      • getPort

        protected int getPort​()
        Returns the value of this socket's port field.
        Returns:
        the value of this socket's port field.
        See Also:
        port
      • supportsUrgentData

        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
        Since:
        1.4
        See Also:
        address
      • sendUrgentData

        protected 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
        Parameters:
        data - The byte of data to send
        Throws:
        IOException - if there is an error sending the data.
        Since:
        1.4
      • getLocalPort

        protected int getLocalPort​()
        Returns the value of this socket's localport field.
        Returns:
        the value of this socket's localport field.
        See Also:
        localport
      • toString

        public String toString​()
        Returns the address and port of this socket as a String.
        Overrides:
        toString in class Object
        Returns:
        a string representation of this socket.
      • setPerformancePreferences

        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
        Since:
        1.5
      • setOption

        protected <T> void setOption​(SocketOption<T> name,
                                     T value)
                              throws IOException
        Called to set a socket option.
        Type Parameters:
        T - The type of the socket option value
        Parameters:
        name - The socket option
        value - The value of the socket option. A value of null may be valid for some options.
        Throws:
        UnsupportedOperationException - if the SocketImpl does not support the option
        IOException - if an I/O error occurs, or if the socket is closed.
        Since:
        9
      • getOption

        protected <T> T getOption​(SocketOption<T> name)
                           throws IOException
        Called to get a socket option.
        Type Parameters:
        T - The type of the socket option value
        Parameters:
        name - The socket option
        Returns:
        the value of the named option
        Throws:
        UnsupportedOperationException - if the SocketImpl does not support the option.
        IOException - if an I/O error occurs, or if the socket is closed.
        Since:
        9
      • supportedOptions

        protected Set<SocketOption<?>> supportedOptions​()
        Returns a set of SocketOptions supported by this impl and by this impl's socket (Socket or ServerSocket)
        Returns:
        a Set of SocketOptions
        Since:
        9