The java.net package contains classes and interfaces that provide a powerful infrastructure for networking in Java. Many of the classes in this package provide support for working with sockets in Java. For example, the Socket and ServerSocket classes make it possible to implement client and server programs that communicate using a reliable, connection-oriented protocol. The DatagramSocket, DatagramPacket, and MulticastSocket classes, on the other hand, all provide support for communication over a connectionless protocol. The MulticastSocket class is new in Java 1.1.
The URL and URLConnection classes define methods for working with uniform resource locators (URLs). The URL class supports basic access to data stored at a URL, while URLConnection offers complete control over all aspects of working with a URL.
The InetAddress class represents network addresses, so InetAddress objects are used by a number of the methods in other classes in java.net.
Chapter 8, Networking, offers a short tutorial on using the networking classes provided by the java.net package. See Chapter 15, The java.net Package, for complete reference material on all of the classes in this package.