public interface SocketFactory
An instance of this interface can be passed to methods that allocate sockets. In this way, the actual, underlying type of socket allocated can be replaced (for instance, with an SSL socket or an firewall-tunnelling socket), without the user of the socket having to explicitly be aware of the underlying implementation.
In some ways, this class is a replacement for the
SocketImplFactory
class. This class addresses the following
issues.
SocketImplFactory
may be installed only once for the entire
process, so different policies cannot be used concurrently and/or
consectively. For instance, imagine a situation where the user wants one
part of the program talking via SSL to some port on machine A and via
standard sockets to some port on machine B. It is not possible to
install separate SocketImplFactory
objects to allow both.
Socket
class presumes a highly-connected network
with the ability to resolve hostnames to IP addresses. The standard
Socket
class always converts the hostname to an IP address
before calling SocketImplFactory
. If the hostname does not
have an IP address, then the SocketImplFactory
never gets a
chance to intercept the host name and perform alternate routing based on
the name. For instance, imagine that the user has implemented a
firewall-tunnelling socket; the raw hostname must be passed to the
firewall machine, which allows the socket to be established once some
out-of-band credentials are supplied. But we could never get this far
because the standard Socket
class would have already rejected
the request since the IP address of the target machine was unknown.
Modifier and Type | Field and Description |
---|---|
static SocketFactory |
defaultFactory
The default socket factory.
|
Modifier and Type | Method and Description |
---|---|
java.net.Socket |
newSocket(java.lang.String host,
int port)
Creates a new
Socket that talks to the specified port
on the named host. |
static final SocketFactory defaultFactory
Socket
to the specified host and port, and is exactly
equivalent to calling new Socket(host, port)
.java.net.Socket newSocket(java.lang.String host, int port) throws java.io.IOException
Socket
that talks to the specified port
on the named host.
The implementation may choose any way it wants to provide a
socket-like object (essentially any mechanism that supports
bidirectional communication). The returned Socket
(or
subclass of Socket
) might not be based on TCP/IP, or it
might involve running a TCP/IP stack over some other protocol, or it
might actually redirect all connections via some other proxy machine,
etc.
host
- The host name.port
- The port number.java.io.IOException
- If there is some problem establishing the socket to the
specified port on the named host.