java.net

Class ServerSocket

Known Direct Subclasses:
LocalServerSocket, NIOServerSocket, SSLServerSocket

public class ServerSocket
extends Object

This class models server side sockets. The basic model is that the server socket is created and bound to some well known port. It then listens for and accepts connections. At that point the client and server sockets are ready to communicate with one another utilizing whatever application layer protocol they desire. As with the Socket class, most instance methods of this class simply redirect their calls to an implementation class.

Constructor Summary

ServerSocket()
Constructor that simply sets the implementation.
ServerSocket(int port)
Creates a server socket and binds it to the specified port.
ServerSocket(int port, int backlog)
Creates a server socket and binds it to the specified port.
ServerSocket(int port, int backlog, InetAddress bindAddr)
Creates a server socket and binds it to the specified port.

Method Summary

Socket
accept()
Accepts a new connection and returns a connected Socket instance representing that connection.
void
bind(SocketAddress endpoint)
Binds the server socket to a specified socket address
void
bind(SocketAddress endpoint, int backlog)
Binds the server socket to a specified socket address
void
close()
Closes this socket and stops listening for connections
ServerSocketChannel
getChannel()
Returns the unique ServerSocketChannel object associated with this socket, if any.
InetAddress
getInetAddress()
This method returns the local address to which this socket is bound
int
getLocalPort()
This method returns the local port number to which this socket is bound
SocketAddress
getLocalSocketAddress()
Returns the local socket address
int
getReceiveBufferSize()
This method returns the value of the system level socket option SO_RCVBUF, which is used by the operating system to tune buffer sizes for data transfers.
boolean
getReuseAddress()
Checks if the SO_REUSEADDR option is enabled
int
getSoTimeout()
Retrieves the current value of the SO_TIMEOUT setting.
protected void
implAccept(Socket socket)
This protected method is used to help subclasses override ServerSocket.accept().
boolean
isBound()
Returns true when the socket is bound, otherwise false
boolean
isClosed()
Returns true if the socket is closed, otherwise false
void
setReceiveBufferSize(int size)
This method sets the value for the system level socket option SO_RCVBUF to the specified value.
void
setReuseAddress(boolean on)
Enables/Disables the SO_REUSEADDR option
void
setSoTimeout(int timeout)
Sets the value of SO_TIMEOUT.
static void
setSocketFactory(SocketImplFactory fac)
Sets the SocketImplFactory for all ServerSocket's.
String
toString()
Returns the value of this socket as a String.

Methods inherited from class java.lang.Object

clone, equals, extends Object> getClass, finalize, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Details

ServerSocket

public ServerSocket()
            throws IOException
Constructor that simply sets the implementation.
Throws:
IOException - If an error occurs

ServerSocket

public ServerSocket(int port)
            throws IOException
Creates a server socket and binds it to the specified port. If the port number is 0, a random free port will be chosen. The pending connection queue on this socket will be set to 50.
Parameters:
port - The port number to bind to
Throws:
IOException - If an error occurs
SecurityException - If a security manager exists and its checkListen method doesn't allow the operation

ServerSocket

public ServerSocket(int port,
                    int backlog)
            throws IOException
Creates a server socket and binds it to the specified port. If the port number is 0, a random free port will be chosen. The pending connection queue on this socket will be set to the value passed as arg2.
Parameters:
port - The port number to bind to
backlog - The length of the pending connection queue
Throws:
IOException - If an error occurs
SecurityException - If a security manager exists and its checkListen method doesn't allow the operation

ServerSocket

public ServerSocket(int port,
                    int backlog,
                    InetAddress bindAddr)
            throws IOException
Creates a server socket and binds it to the specified port. If the port number is 0, a random free port will be chosen. The pending connection queue on this socket will be set to the value passed as backlog. The third argument specifies a particular local address to bind t or null to bind to all local address.
Parameters:
port - The port number to bind to
backlog - The length of the pending connection queue
bindAddr - The address to bind to, or null to bind to all addresses
Throws:
IOException - If an error occurs
SecurityException - If a security manager exists and its checkListen method doesn't allow the operation
Since:
1.1

Method Details

accept

public Socket accept()
            throws IOException
Accepts a new connection and returns a connected Socket instance representing that connection. This method will block until a connection is available.
Returns:
socket object for the just accepted connection
Throws:
IOException - If an error occurs
SecurityException - If a security manager exists and its checkListen method doesn't allow the operation
IllegalBlockingModeException - If this socket has an associated channel, and the channel is in non-blocking mode

bind

public void bind(SocketAddress endpoint)
            throws IOException
Binds the server socket to a specified socket address
Parameters:
endpoint - The socket address to bind to
Throws:
IOException - If an error occurs
IllegalArgumentException - If address type is not supported
SecurityException - If a security manager exists and its checkListen method doesn't allow the operation
Since:
1.4

bind

public void bind(SocketAddress endpoint,
                 int backlog)
            throws IOException
Binds the server socket to a specified socket address
Parameters:
endpoint - The socket address to bind to
backlog - The length of the pending connection queue
Throws:
IOException - If an error occurs
IllegalArgumentException - If address type is not supported
SecurityException - If a security manager exists and its checkListen method doesn't allow the operation
Since:
1.4

close

public void close()
            throws IOException
Closes this socket and stops listening for connections
Throws:
IOException - If an error occurs

getChannel

public ServerSocketChannel getChannel()
Returns the unique ServerSocketChannel object associated with this socket, if any.

The socket only has a ServerSocketChannel if its created by ServerSocketChannel.open().

Returns:
the associated socket channel, null if none exists
Since:
1.4

getInetAddress

public InetAddress getInetAddress()
This method returns the local address to which this socket is bound
Returns:
The socket's local address

getLocalPort

public int getLocalPort()
This method returns the local port number to which this socket is bound
Returns:
The socket's port number

getLocalSocketAddress

public SocketAddress getLocalSocketAddress()
Returns the local socket address
Returns:
the local socket address, null if not bound
Since:
1.4

getReceiveBufferSize

public int getReceiveBufferSize()
            throws SocketException
This method returns the value of the system level socket option SO_RCVBUF, which is used by the operating system to tune buffer sizes for data transfers.
Returns:
The receive buffer size.
Throws:
SocketException - If an error occurs or Socket is not connected
Since:
1.4

getReuseAddress

public boolean getReuseAddress()
            throws SocketException
Checks if the SO_REUSEADDR option is enabled
Returns:
true if SO_REUSEADDR is set, false otherwise
Throws:
SocketException - If an error occurs
Since:
1.4

getSoTimeout

public int getSoTimeout()
            throws IOException
Retrieves the current value of the SO_TIMEOUT setting. A value of 0 implies that SO_TIMEOUT is disabled (ie, operations never time out). This is the number of milliseconds a socket operation can block before an InterruptedIOException is thrown.
Returns:
The value of SO_TIMEOUT
Throws:
IOException - If an error occurs
Since:
1.1

implAccept

protected final void implAccept(Socket socket)
            throws IOException
This protected method is used to help subclasses override ServerSocket.accept(). The passed in socket will be connected when this method returns.
Parameters:
socket - The socket that is used for the accepted connection
Throws:
IOException - If an error occurs
IllegalBlockingModeException - If this socket has an associated channel, and the channel is in non-blocking mode
Since:
1.1

isBound

public boolean isBound()
Returns true when the socket is bound, otherwise false
Returns:
true if socket is bound, false otherwise
Since:
1.4

isClosed

public boolean isClosed()
Returns true if the socket is closed, otherwise false
Returns:
true if socket is closed, false otherwise
Since:
1.4

setReceiveBufferSize

public void setReceiveBufferSize(int size)
            throws SocketException
This method sets the value for the system level socket option SO_RCVBUF to the specified value. Note that valid values for this option are specific to a given operating system.
Parameters:
size - The new receive buffer size.
Throws:
SocketException - If an error occurs or Socket is not connected
IllegalArgumentException - If size is 0 or negative
Since:
1.4

setReuseAddress

public void setReuseAddress(boolean on)
            throws SocketException
Enables/Disables the SO_REUSEADDR option
Parameters:
on - true if SO_REUSEADDR should be enabled, false otherwise
Throws:
SocketException - If an error occurs
Since:
1.4

setSoTimeout

public void setSoTimeout(int timeout)
            throws SocketException
Sets the value of SO_TIMEOUT. A value of 0 implies that SO_TIMEOUT is disabled (ie, operations never time out). This is the number of milliseconds a socket operation can block before an InterruptedIOException is thrown.
Parameters:
timeout - The new SO_TIMEOUT value
Throws:
SocketException - If an error occurs
Since:
1.1

setSocketFactory

public static void setSocketFactory(SocketImplFactory fac)
            throws IOException
Sets the SocketImplFactory for all ServerSocket's. This may only be done once per virtual machine. Subsequent attempts will generate an exception. Note that a SecurityManager check is made prior to setting the factory. If insufficient privileges exist to set the factory, an exception will be thrown
Parameters:
fac - the factory to set
Throws:
SecurityException - If this operation is not allowed by the SecurityManager.
IOException - If any other error occurs

toString

public String toString()
Returns the value of this socket as a String.
Overrides:
toString in interface Object
Returns:
This socket represented as a String.

ServerSocket.java -- Class for implementing server side sockets Copyright (C) 1998, 1999, 2000, 2002, 2003, 2004, 2006 Free Software Foundation, Inc. This file is part of GNU Classpath. GNU Classpath is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. GNU Classpath is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with GNU Classpath; see the file COPYING. If not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Linking this library statically or dynamically with other modules is making a combined work based on this library. Thus, the terms and conditions of the GNU General Public License cover the whole combination. As a special exception, the copyright holders of this library give you permission to link this library with independent modules to produce an executable, regardless of the license terms of these independent modules, and to copy and distribute the resulting executable under terms of your choice, provided that you also meet, for each linked independent module, the terms and conditions of the license of that module. An independent module is a module which is not derived from or based on this library. If you modify this library, you may extend this exception to your version of the library, but you are not obligated to do so. If you do not wish to do so, delete this exception statement from your version.