Java Reference
In-Depth Information
Socket
isusedtocreateasocketontheclientside.Itdeclaresseveralconstructors,
including the following pair:
•
Socket(InetAddress address, int port)
createsastreamsocket
and connects it to the specified
port
number at the specified IP
address
.
Thisconstructorthrows
java.io.IOException
whenanI/Oerroroccurs
while creating the socket,
java.lang.IllegalArgumentException
when the argument passed to
port
is outside the valid range of port values,
which is 0 through 65535, and
java.lang.NullPointerException
when
address
is
null
.
•
Socket(String host, int port)
createsastreamsocketandconnects
it to the specified
port
number on the named
host
. When
host
is
null
,
this constructor is equivalent to invoking
Sock-
et(InetAddress.getByName(null), port)
. It throws the same
IOException
and
IllegalArgumentException
instances as the pre-
viousconstructor.However,insteadofthrowing
NullPointerException
,
it throws
UnknownHostException
when the host's IP address couldn't be
determined.
When a
Socket
instance is created via these constructors, it binds to an arbitrary
localhostsocketaddressbeforeconnectingtotheremotehostsocketaddress.
Binding
makes a client socket address available to a server socket so that a server process can
communicate with the client process via the server socket.
Socket
offers additional constructors to give you flexibility. For example,
Sock-
et()
and
Socket(Proxy proxy)
create unbound and unconnected sockets. Be-
fore you can use these sockets, you need to bind them to local socket addresses
by calling
void bind(SocketAddress bindpoint)
, and then make con-
nections by calling
Socket
's
connect()
methods, such as
void
con-
nect(SocketAddress endpoint)
.
Note
A
proxy
isacomputerthatsitsbetweenanintranetandtheInternetforsecurity
purposes.Proxysettingsarerepresentedbyinstancesofthe
java.net.Proxy
class
and help sockets communicate through proxies.
Another constructor is
Socket(InetAddress address, int port,
InetAddress localAddr, int localPort)
, which lets you specify your
own local host socket address via
localAddr
and
localPort
. This constructor
automaticallybindstothelocalsocketaddressandthenattemptsaconnectiontothere-
mote
address
.
