public Interface SocketOptions

See StandardSocketOptions#IP_MULTICAST_IF for description of this socket option.

This option is used to both set and fetch the outgoing interface on which the multicast packets are sent. Useful on hosts with multiple network interfaces, where applications want to use other than the system default. This option supports setting outgoing interfaces with either IPv4 and IPv6 addresses.

See StandardSocketOptions#IP_MULTICAST_LOOP for description of this socket option.

See StandardSocketOptions#IP_TOS for description of this socket option.

Fetch the local address binding of a socket. This option cannot be set and can only be fetched. The default local address of a socket is INADDR_ANY, meaning any local address on a multi-homed host. A multi-homed host can use this option to accept connections to only one of its addresses (in the case of a ServerSocket or DatagramSocket), or to specify its return address to the peer (for a Socket or DatagramSocket). The type of this option's value is an InetAddress.

See StandardSocketOptions#SO_BROADCAST for description of this socket option.

See StandardSocketOptions#SO_KEEPALIVE for description of this socket option.

See StandardSocketOptions#SO_LINGER for description of this socket option.

Set the value to Boolean.FALSE or an integer less than 0 with setOption(int, Object) to disable this option. An integer greater than or equal to 0 will enable the option and will represent the linger interval.

If this option is enabled then getOption(int) will return an integer value representing the linger interval, else the return value will be Boolean.FALSE.

When this option is set, any TCP urgent data received on the socket will be received through the socket input stream. When the option is disabled (which is the default) urgent data is silently discarded.

See StandardSocketOptions#SO_RCVBUF for description of this socket option.

See StandardSocketOptions#SO_REUSEADDR for description of this socket option.

See StandardSocketOptions#SO_REUSEPORT for description of this socket option.

See StandardSocketOptions#SO_SNDBUF for description of this socket option.

This option is used to both set and fetch a timeout value on blocking Socket operations:

• ServerSocket.accept()
• Socket InputStream.read()
• DatagramSocket.receive()

This option must be set prior to entering a blocking operation to take effect. If the timeout expires and the operation would continue to block, then java.io.InterruptedIOException is raised. The Socket is not closed in such cases.

See StandardSocketOptions#TCP_NODELAY for description of this socket option.

Fetch the value of an option. Binary options will return Boolean#TRUE if enabled, Boolean#FALSE if disabled, e.g.:

SocketImpl s;
...
Boolean noDelay = (Boolean)(s.getOption(TCP_NODELAY));
if (noDelay.booleanValue()) {
    // true if TCP_NODELAY is enabled...
...
}

For options that take a particular type as a parameter, this method will return the parameter's value, else it will return Boolean#FALSE:

Object o = s.getOption(SO_LINGER);
if (o instanceof Integer) {
    System.out.print("Linger time is " + ((Integer)o).intValue());
} else {
  // the true type of o is java.lang.Boolean.FALSE;
}

Parameters

optID:int

an int identifying the option to fetch

Returns:Object

the value of the option

Exceptions

SocketException:

if the socket is closed or if optID is unknown along the protocol stack

See Also

setOption(int, java.lang.Object)

Enable/disable the option specified by optID. If the option is to be enabled, and it takes an option-specific "value", this is passed in value. The actual type of value is option-specific, and it is an error to pass something that isn't of the expected type:

SocketImpl s;
...
s.setOption(SO_LINGER, Integer.valueOf(10));
   // OK - set SO_LINGER w/ timeout of 10 sec.
s.setOption(SO_LINGER, Double.valueOf(10));
   // ERROR - expects java.lang.Integer

s.setOption(TCP_NODELAY, Boolean.TRUE);
   // OK - enables TCP_NODELAY, a binary option

s.setOption(TCP_NODELAY, Boolean.FALSE);
   // OK - disables TCP_NODELAY
s.setOption(SO_LINGER, Boolean.FALSE);
   // OK - disables SO_LINGER

Parameters

optID:int

identifies the option

value:Object

the parameter of the socket option

Exceptions

SocketException:

if the option is unrecognized, the socket is closed, or some low-level error occurred

See Also

getOption(int)