java.net
インタフェース 
ContentHandlerFactory
DatagramSocketImplFactory
FileNameMap
SocketOptions
URLStreamHandlerFactory
クラス 
ContentHandler
DatagramPacket
DatagramSocket
DatagramSocketImpl
Inet4Address
Inet6Address
InetAddress
InetSocketAddress
JarURLConnection
NetPermission
NetworkInterface
SocketAddress
SocketPermission
URL
URLClassLoader
URLConnection
URLStreamHandler
例外 
BindException
MalformedURLException
PortUnreachableException
ProtocolException
SocketException
SocketTimeoutException
UnknownHostException
UnknownServiceException