Java Reference
In-Depth Information
A number of constants are defined in the interface
SocketOptions
. These constants are
used as settings to customize a client socket. We do not implement the
SocketOptions
inter-
face directly, but we have access to its constants through getter and setter methods in the
Socket
class. In the sections that follow, we discuss a few of the more useful options.
Using SO_TIMEOUT
When reading data from a socket through the use of the input stream's
read
method
,
the call
blocks other requests as determined by this setting. The
SO_TIMEOUT
option determines the
amount of time in milliseconds that blocking operations can block until they time out. If the
operation does not complete in the allotted time, then a
java.net.SocketTimeoutException
is
thrown, as shown in Figure 7-1. If this option has not been set or is set to 0, then the call blocks
requests until complete and will not time out.
Figure 7-1.
A SocketTimeoutException
The
Socket
methods used for setting and getting this option are as follows:
public void
setSoTimeout
(int timeout) throws SocketException
public int
getSoTimeout
() throws SocketException
We use this option in
DVDSocketServer.java
, although we could just as easily have used
this option in our socket client,
DVDSocketClient.java
. The following line will shut down the
socket server after 1 minute, or 60,0000 milliseconds, of inactivity:
serverSocket.setSoTimeout(60000);
After the specified time elapses, a
java.net.SocketTimeoutException
is thrown. Figure 7.1
illustrates the
DVDSocketServer
console when the exception occurs.
Using SO_SNDBUF
This option sets the buffer size for data transmissions from this socket. When setting this
option, it is merely a suggestion, or a hint, to the platform about the size of buffer the applica-
tion requires for output operations over the socket. The getter indicates the actual size of the
output buffer. These two methods can be used together to determine whether the platform
