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.
*
* @author unascribed
* @since JDK1.0
*/
public abstract class SocketImpl implements SocketOptions {
/**
* The actual Socket object.
*/
Socket socket = null;
ServerSocket serverSocket = null;
/**
* The file descriptor object for this socket.
*/
protected FileDescriptor fd;
/**
* The IP address of the remote end of this socket.
*/
protected InetAddress address;
/**
* The port number on the remote host to which this socket is connected.
*/
protected int port;
/**
* The local port number to which this socket is connected.
*/
protected int localport;
/**
* Creates either a stream or a datagram socket.
*
* @param stream if true, create a stream socket;
* otherwise, create a datagram socket.
* @exception IOException if an I/O error occurs while creating the
* socket.
*/
protected abstract void create(boolean stream) throws IOException;
/**
* Connects this socket to the specified port on the named host.
*
* @param host the name of the remote host.
* @param port the port number.
* @exception IOException if an I/O error occurs when connecting to the
* remote host.
*/
protected abstract void connect(String host, int port) throws IOException;
/**
* Connects this socket to the specified port number on the specified host.
*
* @param address the IP address of the remote host.
* @param port the port number.
* @exception IOException if an I/O error occurs when attempting a
* connection.
*/
protected abstract void connect(InetAddress address, int port) 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.
*
* @param address the Socket address of the remote host.
* @param timeout the timeout value, in milliseconds, or zero for no timeout.
* @exception IOException if an I/O error occurs when attempting a
* connection.
* @since 1.4
*/
protected abstract void connect(SocketAddress address, int timeout) throws IOException;
/**
* Binds this socket to the specified local IP address and port number.
*
* @param host an IP address that belongs to a local interface.
* @param port the port number.
* @exception IOException if an I/O error occurs when binding this socket.
*/
protected abstract void bind(InetAddress host, int port) 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.
*
* @param backlog the maximum length of the queue.
* @exception IOException if an I/O error occurs when creating the queue.
*/
protected abstract void listen(int backlog) throws IOException;
/**
* Accepts a connection.
*
* @param s the accepted connection.
* @exception IOException if an I/O error occurs when accepting the
* connection.
*/
protected abstract void accept(SocketImpl s) throws IOException;
/**
* Returns an input stream for this socket.
*
* @return a stream for reading from this socket.
* @exception IOException if an I/O error occurs when creating the
* input stream.
*/
protected abstract InputStream getInputStream() throws IOException;
/**
* Returns an output stream for this socket.
*
* @return an output stream for writing to this socket.
* @exception IOException if an I/O error occurs when creating the
* output stream.
*/
protected abstract OutputStream getOutputStream() throws IOException;
/**
* Returns the number of bytes that can be read from this socket
* without blocking.
*
* @return the number of bytes that can be read from this socket
* without blocking.
* @exception IOException if an I/O error occurs when determining the
* number of bytes available.
*/
protected abstract int available() throws IOException;
/**
* Closes this socket.
*
* @exception IOException if an I/O error occurs when closing this socket.
*/
protected abstract void close() 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
* shutdownInput() on the socket, the stream will return EOF.
*
* @exception IOException if an I/O error occurs when shutting down this
* socket.
* @see java.net.Socket#shutdownOutput()
* @see java.net.Socket#close()
* @see java.net.Socket#setSoLinger(boolean, int)
* @since 1.3
*/
protected void shutdownInput() throws IOException {
throw new IOException("Method not implemented!");
}
/**
* 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.
*
* @exception IOException if an I/O error occurs when shutting down this
* socket.
* @see java.net.Socket#shutdownInput()
* @see java.net.Socket#close()
* @see java.net.Socket#setSoLinger(boolean, int)
* @since 1.3
*/
protected void shutdownOutput() throws IOException {
throw new IOException("Method not implemented!");
}
/**
* Returns the value of this socket's fd field.
*
* @return the value of this socket's fd field.
* @see java.net.SocketImpl#fd
*/
protected FileDescriptor getFileDescriptor() {
return fd;
}
/**
* Returns the value of this socket's address field.
*
* @return the value of this socket's address field.
* @see java.net.SocketImpl#address
*/
protected InetAddress getInetAddress() {
return address;
}
/**
* Returns the value of this socket's port field.
*
* @return the value of this socket's port field.
* @see java.net.SocketImpl#port
*/
protected int getPort() {
return port;
}
/**
* Returns whether or not this SocketImpl supports sending
* urgent data. By default, false is returned
* unless the method is overridden in a sub-class
*
* @return true if urgent data supported
* @see java.net.SocketImpl#address
* @since 1.4
*/
protected boolean supportsUrgentData () {
return false; // must be overridden in sub-class
}
/**
* Send one byte of urgent data on the socket.
* The byte to be sent is the low eight bits of the parameter
* @param data The byte of data to send
* @exception IOException if there is an error
* sending the data.
* @since 1.4
*/
protected abstract void sendUrgentData (int data) throws IOException;
/**
* Returns the value of this socket's localport field.
*
* @return the value of this socket's localport field.
* @see java.net.SocketImpl#localport
*/
protected int getLocalPort() {
return localport;
}
void setSocket(Socket soc) {
this.socket = soc;
}
Socket getSocket() {
return socket;
}
void setServerSocket(ServerSocket soc) {
this.serverSocket = soc;
}
ServerSocket getServerSocket() {
return serverSocket;
}
/**
* Returns the address and port of this socket as a String.
*
* @return a string representation of this socket.
*/
public String toString() {
return "Socket[addr=" + getInetAddress() +
",port=" + getPort() + ",localport=" + getLocalPort() + "]";
}
void reset() throws IOException {
address = null;
port = 0;
localport = 0;
}
/**
* 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. * * @param connectionTime * An int expressing the relative importance of a short * connection time * * @param latency * An int expressing the relative importance of low * latency * * @param bandwidth * An int expressing the relative importance of high * bandwidth * * @since 1.5 */ protected void setPerformancePreferences(int connectionTime, int latency, int bandwidth) { /* Not implemented yet */ } }