OpenJDK 1.23 · java.net.ServerSocket · APIdia, the JavaDoc alternative

Socket options
Option Name	Description
`SO_RCVBUF`	The size of the socket receive buffer
`SO_REUSEADDR`	Re-use address

Modifier and Type	Field and Description
private volatile boolean	bound
private volatile boolean	closed
private volatile boolean	created
private static volatile SocketImplFactory	factory The factory for all server sockets.
private final SocketImpl	impl
private volatile Set<SocketOption<?>>	options
private final Object	socketLock

Access	Constructor and Description
private	ServerSocket(Void unused, SocketImpl impl) Creates a server socket with the given `SocketImpl`.
protected	ServerSocket(SocketImpl an instance of a SocketImpl to use on the ServerSocket. impl) Creates a server socket with a user-specified `SocketImpl`.
public	ServerSocket() Creates an unbound server socket.
public	ServerSocket(int the port number, or `0` to use a port number that is automatically allocated. port) Creates a server socket, bound to the specified port.
public	ServerSocket(int the port number, or `0` to use a port number that is automatically allocated. port, int requested maximum length of the queue of incoming connections. backlog) Creates a server socket and binds it to the specified local port number, with the specified backlog.
public	ServerSocket(int the port number, or `0` to use a port number that is automatically allocated. port, int requested maximum length of the queue of incoming connections. backlog, InetAddress the local InetAddress the server will bind to bindAddr) Create a server with the specified port, listen backlog, and local IP address to bind to.

Method Summary

Modifier and Type	Method and Description
public Socket	Returns: the new Socket accept() Listens for a connection to be made to this socket and accepts it.
public void	bind(SocketAddress The IP address and port number to bind to. endpoint) Binds the `ServerSocket` to a specific address (IP address and port number).
public void	bind(SocketAddress The IP address and port number to bind to. endpoint, int requested maximum length of the queue of incoming connections. backlog) Binds the `ServerSocket` to a specific address (IP address and port number).
private static Void	checkPermission()
public void	close() Implements java.io.Closeable.close. Closes this socket.
private static SocketImpl	createImpl() Create a SocketImpl for a server socket.
private void	customImplAccept(SocketImpl si) Accepts a new connection with the given custom SocketImpl.
private void	ensureCompatible(SocketImpl si) Throws IOException if the server SocketImpl and the given client SocketImpl are not both platform or custom SocketImpls.
public ServerSocketChannel	Returns: the server-socket channel associated with this socket, or `null` if this socket was not created for a channel getChannel() Returns the unique `java.nio.channels.ServerSocketChannel` object associated with this socket, if any.
private SocketImpl	getImpl() Returns the `SocketImpl` for this ServerSocket, creating the underlying socket if required.
public InetAddress	Returns: the address to which this socket is bound, or the loopback address if denied by the security manager, or `null` if the socket is unbound. getInetAddress() Returns the local address of this server socket.
public int	Returns: the port number to which this socket is listening or -1 if the socket is not bound yet. getLocalPort() Returns the port number on which this socket is listening.
public SocketAddress	Returns: a `SocketAddress` representing the local endpoint of this socket, or a `SocketAddress` representing the loopback address if denied by the security manager, or `null` if the socket is not bound yet. getLocalSocketAddress() Returns the address of the endpoint this socket is bound to.
public < The type of the socket option value T> T	Returns: The value of the socket option. getOption(SocketOption<T> The socket option name) Returns the value of a socket option.
public int	Returns: the value of the `SO_RCVBUF` option for this `Socket`. getReceiveBufferSize() Gets the value of the `SO_RCVBUF` option for this `ServerSocket`, that is the proposed buffer size that will be used for Sockets accepted from this `ServerSocket`.
public boolean	Returns: a `boolean` indicating whether or not `SO_REUSEADDR` is enabled. getReuseAddress() Tests if `SO_REUSEADDR` is enabled.
public int	Returns: the `SO_TIMEOUT` value getSoTimeout() Retrieve setting for `SO_TIMEOUT`.
protected final void	implAccept(Socket the Socket s) Subclasses of ServerSocket use this method to override accept() to return their own subclass of socket.
private SocketImpl	Returns: the new SocketImpl implAccept() Accepts a connection with a new SocketImpl.
private void	implAccept(SocketImpl si) Accepts a new connection so that the given SocketImpl is connected to the peer.
public boolean	Returns: true if the ServerSocket successfully bound to an address isBound() Returns the binding state of the ServerSocket.
public boolean	Returns: true if the socket has been closed isClosed() Returns the closed state of the ServerSocket.
private SocketImpl	Returns: the new platform SocketImpl platformImplAccept() Accepts a connection with a new platform SocketImpl.
public < The type of the socket option value T> ServerSocket	Returns: this ServerSocket setOption(SocketOption<T> The socket option name, T The value of the socket option. A value of `null` may be valid for some options. value) Sets the value of a socket option.
public void	setPerformancePreferences(int An `int` expressing the relative importance of a short connection time connectionTime, int An `int` expressing the relative importance of low latency latency, int An `int` expressing the relative importance of high bandwidth bandwidth) Sets performance preferences for this ServerSocket.
public void	setReceiveBufferSize(int the size to which to set the receive buffer size. This value must be greater than 0. size) Sets a default proposed value for the `SO_RCVBUF` option for sockets accepted from this `ServerSocket`.
public void	setReuseAddress(boolean whether to enable or disable the socket option on) Enable/disable the `SO_REUSEADDR` socket option.
public static synchronized void	setSocketFactory(SocketImplFactory the desired factory. fac) Deprecated since 17. Use a `javax.net.ServerSocketFactory` and subclass `ServerSocket` directly. Sets the server socket implementation factory for the application.
public void	setSoTimeout(int the specified timeout, in milliseconds timeout) Enable/disable `SO_TIMEOUT` with the specified timeout, in milliseconds.
public Set<SocketOption<?>>	Returns: A set of the socket options supported by this socket. This set may be empty if the socket's SocketImpl cannot be created. supportedOptions() Returns a set of the socket options supported by this server socket.
public String	Returns: a string representation of this socket. toString() Overrides java.lang.Object.toString. Returns the implementation address and implementation port of this socket as a `String`.

Inherited from java.lang.Object:: clone equals finalize getClass hashCode notify notifyAll wait wait wait

Field Detail

bound	back to summary
private volatile boolean bound

closed	back to summary
private volatile boolean closed

created	back to summary
private volatile boolean created

factory	back to summary
private static volatile SocketImplFactory factory The factory for all server sockets.

impl	back to summary
private final SocketImpl impl

options	back to summary
private volatile Set<SocketOption<?>> options

socketLock	back to summary
private final Object socketLock

Constructor Detail

ServerSocket	back to summary
private ServerSocket(Void unused, SocketImpl impl) Creates a server socket with the given `SocketImpl`.

ServerSocket back to summary

ServerSocket	back to summary
protected ServerSocket(SocketImpl impl) Creates a server socket with a user-specified `SocketImpl`. Parameters impl:SocketImpl an instance of a SocketImpl to use on the ServerSocket. Exceptions NullPointerException: if impl is `null`. SecurityException: if a security manager is set and its `checkPermission` method doesn't allow `NetPermission("setSocketImpl")`. Since 12

protected ServerSocket(SocketImpl impl)

Creates a server socket with a user-specified SocketImpl.

Parameters

impl:SocketImpl: an instance of a SocketImpl to use on the ServerSocket.

Exceptions

NullPointerException:: if impl is null.
SecurityException:: if a security manager is set and its checkPermission method doesn't allow NetPermission("setSocketImpl").

Since

ServerSocket	back to summary
public ServerSocket() throws IOException Creates an unbound server socket. Exceptions IOException: IO error when opening the socket.

ServerSocket

back to summary

public ServerSocket() throws IOException

Creates an unbound server socket.

Exceptions

IOException:: IO error when opening the socket.

ServerSocket back to summary

ServerSocket	back to summary
public ServerSocket(int port) throws IOException Creates a server socket, bound to the specified port. A port number of `0` means that the port number is automatically allocated, typically from an ephemeral port range. This port number can then be retrieved by calling `getLocalPort`. The maximum queue length for incoming connection indications (a request to connect) is set to `50`. If a connection indication arrives when the queue is full, the connection is refused. If the application has specified a server socket implementation factory, that factory's createSocketImpl method is called to create the actual socket implementation. Otherwise a system-default socket implementation is created. If there is a security manager, its `checkListen` method is called with the `port` argument as its argument to ensure the operation is allowed. This could result in a SecurityException. Parameters port:int the port number, or `0` to use a port number that is automatically allocated. Exceptions IOException: if an I/O error occurs when opening the socket. SecurityException: if a security manager exists and its `checkListen` method doesn't allow the operation. IllegalArgumentException: if the port parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive. See Also `SecurityManager#checkListen`

public ServerSocket(int port) throws IOException

Creates a server socket, bound to the specified port. A port number of 0 means that the port number is automatically allocated, typically from an ephemeral port range. This port number can then be retrieved by calling getLocalPort.

The maximum queue length for incoming connection indications (a request to connect) is set to 50. If a connection indication arrives when the queue is full, the connection is refused.

If the application has specified a server socket implementation factory, that factory's createSocketImpl method is called to create the actual socket implementation. Otherwise a system-default socket implementation is created.

If there is a security manager, its checkListen method is called with the port argument as its argument to ensure the operation is allowed. This could result in a SecurityException.

Parameters

port:int: the port number, or 0 to use a port number that is automatically allocated.

Exceptions

IOException:: if an I/O error occurs when opening the socket.
SecurityException:: if a security manager exists and its checkListen method doesn't allow the operation.
IllegalArgumentException:: if the port parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive.

See Also

SecurityManager#checkListen

ServerSocket back to summary

ServerSocket	back to summary
public ServerSocket(int port, int backlog) throws IOException Creates a server socket and binds it to the specified local port number, with the specified backlog. A port number of `0` means that the port number is automatically allocated, typically from an ephemeral port range. This port number can then be retrieved by calling `getLocalPort`. The maximum queue length for incoming connection indications (a request to connect) is set to the `backlog` parameter. If a connection indication arrives when the queue is full, the connection is refused. If the application has specified a server socket implementation factory, that factory's createSocketImpl method is called to create the actual socket implementation. Otherwise a system-default socket implementation is created. If there is a security manager, its `checkListen` method is called with the `port` argument as its argument to ensure the operation is allowed. This could result in a SecurityException. The `backlog` argument is the requested maximum number of pending connections on the socket. Its exact semantics are implementation specific. In particular, an implementation may impose a maximum length or may choose to ignore the parameter altogether. The value provided should be greater than `0`. If it is less than or equal to `0`, then an implementation specific default will be used. Parameters port:int the port number, or `0` to use a port number that is automatically allocated. backlog:int requested maximum length of the queue of incoming connections. Exceptions IOException: if an I/O error occurs when opening the socket. SecurityException: if a security manager exists and its `checkListen` method doesn't allow the operation. IllegalArgumentException: if the port parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive. See Also `SecurityManager#checkListen`

public ServerSocket(int port, int backlog) throws IOException

Creates a server socket and binds it to the specified local port number, with the specified backlog. A port number of 0 means that the port number is automatically allocated, typically from an ephemeral port range. This port number can then be retrieved by calling getLocalPort.

The maximum queue length for incoming connection indications (a request to connect) is set to the backlog parameter. If a connection indication arrives when the queue is full, the connection is refused.

If there is a security manager, its checkListen method is called with the port argument as its argument to ensure the operation is allowed. This could result in a SecurityException. The backlog argument is the requested maximum number of pending connections on the socket. Its exact semantics are implementation specific. In particular, an implementation may impose a maximum length or may choose to ignore the parameter altogether. The value provided should be greater than 0. If it is less than or equal to 0, then an implementation specific default will be used.

Parameters

port:int: the port number, or 0 to use a port number that is automatically allocated.
backlog:int: requested maximum length of the queue of incoming connections.

Exceptions

IOException:: if an I/O error occurs when opening the socket.
SecurityException:: if a security manager exists and its checkListen method doesn't allow the operation.
IllegalArgumentException:: if the port parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive.

See Also

SecurityManager#checkListen

ServerSocket back to summary

ServerSocket	back to summary
public ServerSocket(int port, int backlog, InetAddress bindAddr) throws IOException Create a server with the specified port, listen backlog, and local IP address to bind to. The bindAddr argument can be used on a multi-homed host for a ServerSocket that will only accept connect requests to one of its addresses. If bindAddr is null, it will default accepting connections on any/all local addresses. The port must be between 0 and 65535, inclusive. A port number of `0` means that the port number is automatically allocated, typically from an ephemeral port range. This port number can then be retrieved by calling `getLocalPort`. If there is a security manager, this method calls its `checkListen` method with the `port` argument as its argument to ensure the operation is allowed. This could result in a SecurityException. The `backlog` argument is the requested maximum number of pending connections on the socket. Its exact semantics are implementation specific. In particular, an implementation may impose a maximum length or may choose to ignore the parameter altogether. The value provided should be greater than `0`. If it is less than or equal to `0`, then an implementation specific default will be used. Parameters port:int the port number, or `0` to use a port number that is automatically allocated. backlog:int requested maximum length of the queue of incoming connections. bindAddr:InetAddress the local InetAddress the server will bind to Annotations @SuppressWarnings:this-escape Exceptions IOException: if an I/O error occurs when opening the socket. SecurityException: if a security manager exists and its `checkListen` method doesn't allow the operation. IllegalArgumentException: if the port parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive. Since 1.1 See Also `SecurityManager#checkListen`

public ServerSocket(int port, int backlog, InetAddress bindAddr) throws IOException

Create a server with the specified port, listen backlog, and local IP address to bind to. The bindAddr argument can be used on a multi-homed host for a ServerSocket that will only accept connect requests to one of its addresses. If bindAddr is null, it will default accepting connections on any/all local addresses. The port must be between 0 and 65535, inclusive. A port number of 0 means that the port number is automatically allocated, typically from an ephemeral port range. This port number can then be retrieved by calling getLocalPort.

If there is a security manager, this method calls its checkListen method with the port argument as its argument to ensure the operation is allowed. This could result in a SecurityException. The backlog argument is the requested maximum number of pending connections on the socket. Its exact semantics are implementation specific. In particular, an implementation may impose a maximum length or may choose to ignore the parameter altogether. The value provided should be greater than 0. If it is less than or equal to 0, then an implementation specific default will be used.

Parameters

port:int: the port number, or 0 to use a port number that is automatically allocated.
backlog:int: requested maximum length of the queue of incoming connections.
bindAddr:InetAddress: the local InetAddress the server will bind to

Annotations

@SuppressWarnings:this-escape

Exceptions

IOException:: if an I/O error occurs when opening the socket.
SecurityException:: if a security manager exists and its checkListen method doesn't allow the operation.
IllegalArgumentException:: if the port parameter is outside the specified range of valid port values, which is between 0 and 65535, inclusive.

Since

1.1

See Also

SecurityManager#checkListen

Method Detail

accept back to summary

accept	back to summary
public Socket accept() throws IOException Listens for a connection to be made to this socket and accepts it. The method blocks until a connection is made. This method is interruptible in the following circumstances: The socket is associated with a `ServerSocketChannel`. In that case, interrupting a thread accepting a connection will close the underlying channel and cause this method to throw `java.nio.channels.ClosedByInterruptException` with the interrupt status set. The socket uses the system-default socket implementation and a virtual thread is accepting a connection. In that case, interrupting the virtual thread will cause it to wakeup and close the socket. This method will then throw `SocketException` with the interrupt status set. A new Socket `s` is created and, if there is a security manager, the security manager's `checkAccept` method is called with `s.getInetAddress().getHostAddress()` and `s.getPort()` as its arguments to ensure the operation is allowed. This could result in a SecurityException. Implementation Note An instance of this class using a system-default `SocketImpl` accepts sockets with a `SocketImpl` of the same type, regardless of the client socket implementation factory, if one has been set. Returns:Socket the new Socket Exceptions IOException: if an I/O error occurs when waiting for a connection. SecurityException: if a security manager exists and its `checkAccept` method doesn't allow the operation. SocketTimeoutException: if a timeout was previously set with setSoTimeout and the timeout has been reached. IllegalBlockingModeException: if this socket has an associated channel, the channel is in non-blocking mode, and there is no connection ready to be accepted See Also `SecurityManager#checkAccept`

public Socket accept() throws IOException

Listens for a connection to be made to this socket and accepts it. The method blocks until a connection is made.

This method is interruptible in the following circumstances:

The socket is associated with a ServerSocketChannel. In that case, interrupting a thread accepting a connection will close the underlying channel and cause this method to throw java.nio.channels.ClosedByInterruptException with the interrupt status set.
The socket uses the system-default socket implementation and a virtual thread is accepting a connection. In that case, interrupting the virtual thread will cause it to wakeup and close the socket. This method will then throw SocketException with the interrupt status set.

A new Socket s is created and, if there is a security manager, the security manager's checkAccept method is called with s.getInetAddress().getHostAddress() and s.getPort() as its arguments to ensure the operation is allowed. This could result in a SecurityException.

Implementation Note

An instance of this class using a system-default SocketImpl accepts sockets with a SocketImpl of the same type, regardless of the client socket implementation factory, if one has been set.

Returns:Socket

the new Socket

Exceptions

IOException:: if an I/O error occurs when waiting for a connection.
SecurityException:: if a security manager exists and its checkAccept method doesn't allow the operation.
SocketTimeoutException:: if a timeout was previously set with setSoTimeout and the timeout has been reached.
IllegalBlockingModeException:: if this socket has an associated channel, the channel is in non-blocking mode, and there is no connection ready to be accepted

See Also

SecurityManager#checkAccept

bind back to summary

bind	back to summary
public void bind(SocketAddress endpoint) throws IOException Binds the `ServerSocket` to a specific address (IP address and port number). If the address is `null`, then the system will pick up an ephemeral port and a valid local address to bind the socket. Parameters endpoint:SocketAddress The IP address and port number to bind to. Exceptions IOException: if the bind operation fails, or if the socket is already bound. SecurityException: if a `SecurityManager` is present and its `checkListen` method doesn't allow the operation. IllegalArgumentException: if endpoint is a SocketAddress subclass not supported by this socket Since 1.4

public void bind(SocketAddress endpoint) throws IOException

Binds the ServerSocket to a specific address (IP address and port number).

If the address is null, then the system will pick up an ephemeral port and a valid local address to bind the socket.

Parameters

endpoint:SocketAddress: The IP address and port number to bind to.

Exceptions

IOException:: if the bind operation fails, or if the socket is already bound.
SecurityException:: if a SecurityManager is present and its checkListen method doesn't allow the operation.
IllegalArgumentException:: if endpoint is a SocketAddress subclass not supported by this socket

Since

1.4

bind back to summary

bind	back to summary
public void bind(SocketAddress endpoint, int backlog) throws IOException Binds the `ServerSocket` to a specific address (IP address and port number). If the address is `null`, then the system will pick up an ephemeral port and a valid local address to bind the socket. The `backlog` argument is the requested maximum number of pending connections on the socket. Its exact semantics are implementation specific. In particular, an implementation may impose a maximum length or may choose to ignore the parameter altogether. The value provided should be greater than `0`. If it is less than or equal to `0`, then an implementation specific default will be used. Parameters endpoint:SocketAddress The IP address and port number to bind to. backlog:int requested maximum length of the queue of incoming connections. Exceptions IOException: if the bind operation fails, or if the socket is already bound. SecurityException: if a `SecurityManager` is present and its `checkListen` method doesn't allow the operation. IllegalArgumentException: if endpoint is a SocketAddress subclass not supported by this socket Since 1.4

public void bind(SocketAddress endpoint, int backlog) throws IOException

Binds the ServerSocket to a specific address (IP address and port number).

If the address is null, then the system will pick up an ephemeral port and a valid local address to bind the socket.

The backlog argument is the requested maximum number of pending connections on the socket. Its exact semantics are implementation specific. In particular, an implementation may impose a maximum length or may choose to ignore the parameter altogether. The value provided should be greater than 0. If it is less than or equal to 0, then an implementation specific default will be used.

Parameters

endpoint:SocketAddress: The IP address and port number to bind to.
backlog:int: requested maximum length of the queue of incoming connections.

Exceptions

IOException:: if the bind operation fails, or if the socket is already bound.
SecurityException:: if a SecurityManager is present and its checkListen method doesn't allow the operation.
IllegalArgumentException:: if endpoint is a SocketAddress subclass not supported by this socket

Since

1.4

checkPermission	back to summary
private static Void checkPermission()

close back to summary

close	back to summary
public void close() throws IOException Implements java.io.Closeable.close. Closes this socket. Any thread currently blocked in `accept()` will throw a `SocketException`. If this socket has an associated channel then the channel is closed as well. Exceptions IOException: if an I/O error occurs when closing the socket.

public void close() throws IOException

Implements java.io.Closeable.close.

Closes this socket. Any thread currently blocked in accept() will throw a SocketException.

If this socket has an associated channel then the channel is closed as well.

Exceptions

IOException:: if an I/O error occurs when closing the socket.

createImpl	back to summary
private static SocketImpl createImpl() Create a SocketImpl for a server socket. The SocketImpl is created without an underlying socket.

customImplAccept	back to summary
private void customImplAccept(SocketImpl si) throws IOException Accepts a new connection with the given custom SocketImpl.

ensureCompatible	back to summary
private void ensureCompatible(SocketImpl si) throws IOException Throws IOException if the server SocketImpl and the given client SocketImpl are not both platform or custom SocketImpls.

getChannel back to summary

getChannel	back to summary
public ServerSocketChannel getChannel() Returns the unique `java.nio.channels.ServerSocketChannel` object associated with this socket, if any. A server socket will have a channel if, and only if, the channel itself was created via the `ServerSocketChannel.open` method. Returns:ServerSocketChannel the server-socket channel associated with this socket, or `null` if this socket was not created for a channel Since 1.4

public ServerSocketChannel getChannel()

Returns the unique java.nio.channels.ServerSocketChannel object associated with this socket, if any.

A server socket will have a channel if, and only if, the channel itself was created via the ServerSocketChannel.open method.

Returns:ServerSocketChannel: the server-socket channel associated with this socket, or null if this socket was not created for a channel
Since: 1.4

getImpl back to summary

getImpl	back to summary
private SocketImpl getImpl() throws SocketException Returns the `SocketImpl` for this ServerSocket, creating the underlying socket if required. Exceptions SocketException: if creating the underlying socket fails

private SocketImpl getImpl() throws SocketException

Returns the SocketImpl for this ServerSocket, creating the underlying socket if required.

Exceptions

SocketException:: if creating the underlying socket fails

getInetAddress back to summary

getInetAddress	back to summary
public InetAddress getInetAddress() Returns the local address of this server socket. If the socket was bound prior to being `closed`, then this method will continue to return the local address after the socket is closed. If there is a security manager set, its `checkConnect` method is called with the local address and `-1` as its arguments to see if the operation is allowed. If the operation is not allowed, the `loopback` address is returned. Returns:InetAddress the address to which this socket is bound, or the loopback address if denied by the security manager, or `null` if the socket is unbound. See Also `SecurityManager#checkConnect`

public InetAddress getInetAddress()

Returns the local address of this server socket.

If the socket was bound prior to being closed, then this method will continue to return the local address after the socket is closed.

If there is a security manager set, its checkConnect method is called with the local address and -1 as its arguments to see if the operation is allowed. If the operation is not allowed, the loopback address is returned.

Returns:InetAddress: the address to which this socket is bound, or the loopback address if denied by the security manager, or null if the socket is unbound.
See Also: SecurityManager#checkConnect

getLocalPort back to summary

getLocalPort	back to summary
public int getLocalPort() Returns the port number on which this socket is listening. If the socket was bound prior to being `closed`, then this method will continue to return the port number after the socket is closed. Returns:int the port number to which this socket is listening or -1 if the socket is not bound yet.

public int getLocalPort()

Returns the port number on which this socket is listening.

If the socket was bound prior to being closed, then this method will continue to return the port number after the socket is closed.

Returns:int: the port number to which this socket is listening or -1 if the socket is not bound yet.

getLocalSocketAddress back to summary

getLocalSocketAddress	back to summary
public SocketAddress getLocalSocketAddress() Returns the address of the endpoint this socket is bound to. If the socket was bound prior to being `closed`, then this method will continue to return the address of the endpoint after the socket is closed. If there is a security manager set, its `checkConnect` method is called with the local address and `-1` as its arguments to see if the operation is allowed. If the operation is not allowed, a `SocketAddress` representing the `loopback` address and the local port to which the socket is bound is returned. Returns:SocketAddress a `SocketAddress` representing the local endpoint of this socket, or a `SocketAddress` representing the loopback address if denied by the security manager, or `null` if the socket is not bound yet. Since 1.4 See Also `getInetAddress()`, `getLocalPort()`, `bind(SocketAddress)`, `SecurityManager#checkConnect`

public SocketAddress getLocalSocketAddress()

Returns the address of the endpoint this socket is bound to.

If the socket was bound prior to being closed, then this method will continue to return the address of the endpoint after the socket is closed.

Returns:SocketAddress: a SocketAddress representing the local endpoint of this socket, or a SocketAddress representing the loopback address if denied by the security manager, or null if the socket is not bound yet.
Since: 1.4
See Also: getInetAddress(), getLocalPort(), bind(SocketAddress), SecurityManager#checkConnect

getOption back to summary

getOption	back to summary
public <T> T getOption(SocketOption<T> name) throws IOException Returns the value of a socket option. Parameters <T> The type of the socket option value name:SocketOption<T> The socket option Returns:T The value of the socket option. Exceptions IOException: if an I/O error occurs, or if the socket is closed. UnsupportedOperationException: if the server socket does not support the option. NullPointerException: if name is `null` SecurityException: if a security manager is set and if the socket option requires a security permission and if the caller does not have the required permission. `StandardSocketOptions` do not require any security permission. Since 9

public <T> T getOption(SocketOption<T> name) throws IOException

Returns the value of a socket option.

Parameters

<T>: The type of the socket option value
name:SocketOption<T>: The socket option

Returns:T

The value of the socket option.

Exceptions

IOException:: if an I/O error occurs, or if the socket is closed.
UnsupportedOperationException:: if the server socket does not support the option.
NullPointerException:: if name is null
SecurityException:: if a security manager is set and if the socket option requires a security permission and if the caller does not have the required permission. StandardSocketOptions do not require any security permission.

Since

getReceiveBufferSize back to summary

getReceiveBufferSize	back to summary
public int getReceiveBufferSize() throws SocketException Gets the value of the `SO_RCVBUF` option for this `ServerSocket`, that is the proposed buffer size that will be used for Sockets accepted from this `ServerSocket`. Note, the value actually set in the accepted socket is determined by calling `Socket#getReceiveBufferSize()`. Returns:int the value of the `SO_RCVBUF` option for this `Socket`. Exceptions SocketException: if there is an error in the underlying protocol, such as a TCP error. Since 1.4 See Also `setReceiveBufferSize(int)`

public int getReceiveBufferSize() throws SocketException

Gets the value of the SO_RCVBUF option for this ServerSocket, that is the proposed buffer size that will be used for Sockets accepted from this ServerSocket.

Note, the value actually set in the accepted socket is determined by calling Socket#getReceiveBufferSize().

Returns:int

the value of the SO_RCVBUF option for this Socket.

Exceptions

SocketException:: if there is an error in the underlying protocol, such as a TCP error.

Since

1.4

See Also

setReceiveBufferSize(int)

getReuseAddress back to summary

getReuseAddress	back to summary
public boolean getReuseAddress() throws SocketException Tests if `SO_REUSEADDR` is enabled. Returns:boolean a `boolean` indicating whether or not `SO_REUSEADDR` is enabled. Exceptions SocketException: if there is an error in the underlying protocol, such as a TCP error. Since 1.4 See Also `setReuseAddress(boolean)`

public boolean getReuseAddress() throws SocketException

Tests if SO_REUSEADDR is enabled.

Returns:boolean

a boolean indicating whether or not SO_REUSEADDR is enabled.

Exceptions

SocketException:: if there is an error in the underlying protocol, such as a TCP error.

Since

1.4

See Also

setReuseAddress(boolean)

getSoTimeout back to summary

getSoTimeout	back to summary
public int getSoTimeout() throws IOException Retrieve setting for `SO_TIMEOUT`. 0 returns implies that the option is disabled (i.e., timeout of infinity). Returns:int the `SO_TIMEOUT` value Exceptions IOException: if an I/O error occurs Since 1.1 See Also `setSoTimeout(int)`

public int getSoTimeout() throws IOException

Retrieve setting for SO_TIMEOUT. 0 returns implies that the option is disabled (i.e., timeout of infinity).

Returns:int

the SO_TIMEOUT value

Exceptions

IOException:: if an I/O error occurs

Since

1.1

See Also

setSoTimeout(int)

implAccept back to summary

implAccept	back to summary
protected final void implAccept(Socket s) throws IOException Subclasses of ServerSocket use this method to override accept() to return their own subclass of socket. So a FooServerSocket will typically hand this method a newly created, unbound, FooSocket. On return from implAccept the FooSocket will be connected to a client. The behavior of this method is unspecified when invoked with a socket that is not newly created and unbound. Any socket options set on the given socket prior to invoking this method may or may not be preserved when the connection is accepted. It may not be possible to accept a connection when this socket has a `SocketImpl` of one type and the given socket has a `SocketImpl` of a completely different type. Implementation Note An instance of this class using a system-default `SocketImpl` can accept a connection with a Socket using a `SocketImpl` of the same type: `IOException` is thrown if the Socket is using a custom `SocketImpl`. An instance of this class using a custom `SocketImpl` cannot accept a connection with a Socket using a system-default `SocketImpl`. Parameters s:Socket the Socket Exceptions IOException: if an I/O error occurs when waiting for a connection, or if it is not possible for this socket to accept a connection with the given socket IllegalBlockingModeException: if this socket has an associated channel, and the channel is in non-blocking mode Since 1.1

protected final void implAccept(Socket s) throws IOException

Subclasses of ServerSocket use this method to override accept() to return their own subclass of socket. So a FooServerSocket will typically hand this method a newly created, unbound, FooSocket. On return from implAccept the FooSocket will be connected to a client.

The behavior of this method is unspecified when invoked with a socket that is not newly created and unbound. Any socket options set on the given socket prior to invoking this method may or may not be preserved when the connection is accepted. It may not be possible to accept a connection when this socket has a SocketImpl of one type and the given socket has a SocketImpl of a completely different type.

Implementation Note

An instance of this class using a system-default SocketImpl can accept a connection with a Socket using a SocketImpl of the same type: IOException is thrown if the Socket is using a custom SocketImpl. An instance of this class using a custom SocketImpl cannot accept a connection with a Socket using a system-default SocketImpl.

Parameters

s:Socket: the Socket

Exceptions

IOException:: if an I/O error occurs when waiting for a connection, or if it is not possible for this socket to accept a connection with the given socket
IllegalBlockingModeException:: if this socket has an associated channel, and the channel is in non-blocking mode

Since

1.1

implAccept	back to summary
private SocketImpl implAccept() throws IOException Accepts a connection with a new SocketImpl. Returns:SocketImpl the new SocketImpl

implAccept

back to summary

private SocketImpl implAccept() throws IOException

Accepts a connection with a new SocketImpl.

Returns:SocketImpl: the new SocketImpl

implAccept	back to summary
private void implAccept(SocketImpl si) throws IOException Accepts a new connection so that the given SocketImpl is connected to the peer. The SocketImpl and connection are closed if the connection is denied by the security manager. Exceptions IOException: if an I/O error occurs SecurityException: if the security manager's checkAccept method fails

implAccept

back to summary

private void implAccept(SocketImpl si) throws IOException

Accepts a new connection so that the given SocketImpl is connected to the peer. The SocketImpl and connection are closed if the connection is denied by the security manager.

Exceptions

IOException:: if an I/O error occurs
SecurityException:: if the security manager's checkAccept method fails

isBound back to summary

isBound	back to summary
public boolean isBound() Returns the binding state of the ServerSocket. If the socket was bound prior to being closed, then this method will continue to return `true` after the socket is closed. Returns:boolean true if the ServerSocket successfully bound to an address Since 1.4

public boolean isBound()

Returns the binding state of the ServerSocket.

If the socket was bound prior to being closed, then this method will continue to return true after the socket is closed.

Returns:boolean: true if the ServerSocket successfully bound to an address
Since: 1.4

isClosed	back to summary
public boolean isClosed() Returns the closed state of the ServerSocket. Returns:boolean true if the socket has been closed Since 1.4

isClosed

back to summary

public boolean isClosed()

Returns the closed state of the ServerSocket.

Returns:boolean: true if the socket has been closed
Since: 1.4

platformImplAccept	back to summary
private SocketImpl platformImplAccept() throws IOException Accepts a connection with a new platform SocketImpl. Returns:SocketImpl the new platform SocketImpl

platformImplAccept

back to summary

private SocketImpl platformImplAccept() throws IOException

Accepts a connection with a new platform SocketImpl.

Returns:SocketImpl: the new platform SocketImpl

setOption back to summary

setOption	back to summary
public <T> ServerSocket setOption(SocketOption<T> name, T value) throws IOException Sets the value of a socket option. Parameters <T> The type of the socket option value name:SocketOption<T> The socket option value:T The value of the socket option. A value of `null` may be valid for some options. Returns:ServerSocket this ServerSocket Exceptions IOException: if an I/O error occurs, or if the socket is closed. UnsupportedOperationException: if the server socket does not support the option. IllegalArgumentException: if the value is not valid for the option. NullPointerException: if name is `null` SecurityException: if a security manager is set and if the socket option requires a security permission and if the caller does not have the required permission. `StandardSocketOptions` do not require any security permission. Since 9

public <T> ServerSocket setOption(SocketOption<T> name, T value) throws IOException

Sets the value of a socket option.

Parameters

<T>: The type of the socket option value
name:SocketOption<T>: The socket option
value:T: The value of the socket option. A value of null may be valid for some options.

Returns:ServerSocket

this ServerSocket

Exceptions

IOException:: if an I/O error occurs, or if the socket is closed.
UnsupportedOperationException:: if the server socket does not support the option.
IllegalArgumentException:: if the value is not valid for the option.
NullPointerException:: if name is null
SecurityException:: if a security manager is set and if the socket option requires a security permission and if the caller does not have the required permission. StandardSocketOptions do not require any security permission.

Since

setPerformancePreferences back to summary

setPerformancePreferences	back to summary
public void setPerformancePreferences(int connectionTime, int latency, int bandwidth) Sets performance preferences for this ServerSocket. 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. 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)`. Invoking this method after this socket has been bound will have no effect. This implies that in order to use this capability requires the socket to be created with the no-argument constructor. Parameters connectionTime:int An `int` expressing the relative importance of a short connection time latency:int An `int` expressing the relative importance of low latency bandwidth:int An `int` expressing the relative importance of high bandwidth Since 1.5

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

Sets performance preferences for this ServerSocket.

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. 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).

Invoking this method after this socket has been bound will have no effect. This implies that in order to use this capability requires the socket to be created with the no-argument constructor.

Parameters

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

Since

1.5

setReceiveBufferSize back to summary

setReceiveBufferSize	back to summary
public void setReceiveBufferSize(int size) throws SocketException Sets a default proposed value for the `SO_RCVBUF` option for sockets accepted from this `ServerSocket`. The value actually set in the accepted socket must be determined by calling `Socket#getReceiveBufferSize()` after the socket is returned by `accept()`. The value of `SO_RCVBUF` is used both to set the size of the internal socket receive buffer, and to set the size of the TCP receive window that is advertised to the remote peer. It is possible to change the value subsequently, by calling `Socket#setReceiveBufferSize(int)`. However, if the application wishes to allow a receive window larger than 64K bytes, as defined by RFC1323 then the proposed value must be set in the ServerSocket before it is bound to a local address. This implies, that the ServerSocket must be created with the no-argument constructor, then setReceiveBufferSize() must be called and lastly the ServerSocket is bound to an address by calling bind(). Failure to do this will not cause an error, and the buffer size may be set to the requested value but the TCP receive window in sockets accepted from this ServerSocket will be no larger than 64K bytes. Parameters size:int the size to which to set the receive buffer size. This value must be greater than 0. Exceptions SocketException: if there is an error in the underlying protocol, such as a TCP error. IllegalArgumentException: if the value is 0 or is negative. Since 1.4 See Also `getReceiveBufferSize`

public void setReceiveBufferSize(int size) throws SocketException

Sets a default proposed value for the SO_RCVBUF option for sockets accepted from this ServerSocket. The value actually set in the accepted socket must be determined by calling Socket#getReceiveBufferSize() after the socket is returned by accept().

The value of SO_RCVBUF is used both to set the size of the internal socket receive buffer, and to set the size of the TCP receive window that is advertised to the remote peer.

It is possible to change the value subsequently, by calling Socket#setReceiveBufferSize(int). However, if the application wishes to allow a receive window larger than 64K bytes, as defined by RFC1323 then the proposed value must be set in the ServerSocket before it is bound to a local address. This implies, that the ServerSocket must be created with the no-argument constructor, then setReceiveBufferSize() must be called and lastly the ServerSocket is bound to an address by calling bind().

Failure to do this will not cause an error, and the buffer size may be set to the requested value but the TCP receive window in sockets accepted from this ServerSocket will be no larger than 64K bytes.

Parameters

size:int: the size to which to set the receive buffer size. This value must be greater than 0.

Exceptions

SocketException:: if there is an error in the underlying protocol, such as a TCP error.
IllegalArgumentException:: if the value is 0 or is negative.

Since

1.4

See Also

getReceiveBufferSize

setReuseAddress back to summary

setReuseAddress	back to summary
public void setReuseAddress(boolean on) throws SocketException Enable/disable the `SO_REUSEADDR` socket option. When a TCP connection is closed the connection may remain in a timeout state for a period of time after the connection is closed (typically known as the `TIME_WAIT` state or `2MSL` wait state). For applications using a well known socket address or port it may not be possible to bind a socket to the required `SocketAddress` if there is a connection in the timeout state involving the socket address or port. Enabling `SO_REUSEADDR` prior to binding the socket using `bind(SocketAddress)` allows the socket to be bound even though a previous connection is in a timeout state. When a `ServerSocket` is created the initial setting of `SO_REUSEADDR` is not defined. Applications can use `getReuseAddress()` to determine the initial setting of `SO_REUSEADDR`. The behaviour when `SO_REUSEADDR` is enabled or disabled after a socket is bound (See `isBound()`) is not defined. Parameters on:boolean whether to enable or disable the socket option Exceptions SocketException: if an error occurs enabling or disabling the `SO_REUSEADDR` socket option, or the socket is closed. Since 1.4 See Also `getReuseAddress()`, `bind(SocketAddress)`, `isBound()`, `isClosed()`

public void setReuseAddress(boolean on) throws SocketException

Enable/disable the SO_REUSEADDR socket option.

When a TCP connection is closed the connection may remain in a timeout state for a period of time after the connection is closed (typically known as the TIME_WAIT state or 2MSL wait state). For applications using a well known socket address or port it may not be possible to bind a socket to the required SocketAddress if there is a connection in the timeout state involving the socket address or port.

Enabling SO_REUSEADDR prior to binding the socket using bind(SocketAddress) allows the socket to be bound even though a previous connection is in a timeout state.

When a ServerSocket is created the initial setting of SO_REUSEADDR is not defined. Applications can use getReuseAddress() to determine the initial setting of SO_REUSEADDR.

The behaviour when SO_REUSEADDR is enabled or disabled after a socket is bound (See isBound()) is not defined.

Parameters

on:boolean: whether to enable or disable the socket option

Exceptions

SocketException:: if an error occurs enabling or disabling the SO_REUSEADDR socket option, or the socket is closed.

Since

1.4

setSocketFactory back to summary

setSocketFactory	back to summary
public static synchronized void setSocketFactory(SocketImplFactory fac) throws IOException Deprecated since 17. Use a `javax.net.ServerSocketFactory` and subclass `ServerSocket` directly. This method provided a way in early JDK releases to replace the system wide implementation of `ServerSocket`. It has been mostly obsolete since Java 1.4. If required, a `ServerSocket` can be created to use a custom implementation by extending `ServerSocket` and using the protected constructor that takes an implementation as a parameter. Sets the server socket implementation factory for the application. The factory can be specified only once. When an application creates a new server socket, the socket implementation factory's `createSocketImpl` method is called to create the actual socket implementation. Passing `null` to the method is a no-op unless the factory was already set. If there is a security manager, this method first calls the security manager's `checkSetFactory` method to ensure the operation is allowed. This could result in a SecurityException. Parameters fac:SocketImplFactory the desired factory. Annotations @Deprecated since:17 Exceptions IOException: if an I/O error occurs when setting the socket factory. SocketException: if the factory has already been defined. SecurityException: if a security manager exists and its `checkSetFactory` method doesn't allow the operation. See Also `java.net.SocketImplFactory#createSocketImpl()`, `SecurityManager#checkSetFactory`

public static synchronized void setSocketFactory(SocketImplFactory fac) throws IOException

Deprecated

since 17.

Use a javax.net.ServerSocketFactory and subclass ServerSocket directly.
This method provided a way in early JDK releases to replace the system wide implementation of ServerSocket. It has been mostly obsolete since Java 1.4. If required, a ServerSocket can be created to use a custom implementation by extending ServerSocket and using the protected constructor that takes an implementation as a parameter.

Sets the server socket implementation factory for the application. The factory can be specified only once.

When an application creates a new server socket, the socket implementation factory's createSocketImpl method is called to create the actual socket implementation.

Passing null to the method is a no-op unless the factory was already set.

If there is a security manager, this method first calls the security manager's checkSetFactory method to ensure the operation is allowed. This could result in a SecurityException.

Parameters

fac:SocketImplFactory: the desired factory.

Annotations

@Deprecated
since:17

Exceptions

IOException:: if an I/O error occurs when setting the socket factory.
SocketException:: if the factory has already been defined.
SecurityException:: if a security manager exists and its checkSetFactory method doesn't allow the operation.

setSoTimeout back to summary

setSoTimeout	back to summary
public void setSoTimeout(int timeout) throws SocketException Enable/disable `SO_TIMEOUT` with the specified timeout, in milliseconds. With this option set to a positive timeout value, a call to accept() for this ServerSocket will block for only this amount of time. If the timeout expires, a `java.net.SocketTimeoutException` is raised, though the ServerSocket is still valid. A timeout of zero is interpreted as an infinite timeout. The option must be enabled prior to entering the blocking operation to have effect. Parameters timeout:int the specified timeout, in milliseconds Exceptions SocketException: if there is an error in the underlying protocol, such as a TCP error IllegalArgumentException: if `timeout` is negative Since 1.1 See Also `getSoTimeout()`

public void setSoTimeout(int timeout) throws SocketException

Enable/disable SO_TIMEOUT with the specified timeout, in milliseconds. With this option set to a positive timeout value, a call to accept() for this ServerSocket will block for only this amount of time. If the timeout expires, a java.net.SocketTimeoutException is raised, though the ServerSocket is still valid. A timeout of zero is interpreted as an infinite timeout. The option must be enabled prior to entering the blocking operation to have effect.

Parameters

timeout:int: the specified timeout, in milliseconds

Exceptions

SocketException:: if there is an error in the underlying protocol, such as a TCP error
IllegalArgumentException:: if timeout is negative

Since

1.1

See Also

getSoTimeout()

supportedOptions	back to summary
public Set<SocketOption<?>> supportedOptions() Returns a set of the socket options supported by this server socket. This method will continue to return the set of options even after the socket has been closed. Returns:Set<SocketOption<?>> A set of the socket options supported by this socket. This set may be empty if the socket's SocketImpl cannot be created. Since 9

supportedOptions

back to summary

public Set<SocketOption<?>> supportedOptions()

Returns a set of the socket options supported by this server socket. This method will continue to return the set of options even after the socket has been closed.

Returns:Set<SocketOption<?>>: A set of the socket options supported by this socket. This set may be empty if the socket's SocketImpl cannot be created.
Since: 9

toString back to summary

toString	back to summary
public String toString() Overrides java.lang.Object.toString. Returns the implementation address and implementation port of this socket as a `String`. If there is a security manager set, and this socket is bound, its `checkConnect` method is called with the local address and `-1` as its arguments to see if the operation is allowed. If the operation is not allowed, an `InetAddress` representing the `loopback` address is returned as the implementation address. Returns:String a string representation of this socket. Annotations @SuppressWarnings:removal

public String toString()

Overrides java.lang.Object.toString.

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

If there is a security manager set, and this socket is bound, its checkConnect method is called with the local address and -1 as its arguments to see if the operation is allowed. If the operation is not allowed, an InetAddress representing the loopback address is returned as the implementation address.

Returns:String

a string representation of this socket.

Annotations

@SuppressWarnings:removal

public Class ServerSocket

Field Summary

Constructor Summary

Method Summary

Field Detail

Constructor Detail

Method Detail