Java The Complete Reference, Seventh Edition

DatagramSocket NetworkInter face URLClassLoader

DatagramSocketImpl PasswordAuthentication URLConnection

HttpCookie (Added by

Java SE 6.)

Proxy URLDecoder

HttpURLConnection ProxySelector URLEncoder

IDN (Added by Java SE 6.) ResponseCache URLStreamHandler

Inet4Address SecureCacheResponse

Thejava.netpackage’s interfaces are listed here:

ContentHandlerFactor y DatagramSocketImplFactor y SocketOptions

CookiePolicy (Added by Java SE 6.) FileNameMap URLStreamHandlerFactor y

CookieStore (Added by Java SE 6.) SocketImplFactor y

In the sections that follow, we will examine the main networking classes and show

several examples that apply to them. Once you understand these core networking classes,

you will be able to easily explore the others on your own.

InetAddress

TheInetAddressclass is used to encapsulate both the numerical IP address and the domain

name for that address. You interact with this class by using the name of an IP host, which is

more convenient and understandable than its IP address. TheInetAddressclass hides the

number inside.InetAddresscan handle both IPv4 and IPv6 addresses.

Factory Methods

TheInetAddressclass has no visible constructors. To create anInetAddressobject, you

have to use one of the available factory methods.Factory methodsare merely a convention

whereby static methods in a class return an instance of that class. This is done in lieu of

overloading a constructor with various parameter lists when having unique method names

makes the results much clearer. Three commonly usedInetAddressfactory methods are

shown here:

static InetAddress getLocalHost( )

throws UnknownHostException

static InetAddress getByName(StringhostName)

throws UnknownHostException

static InetAddress[ ] getAllByName(StringhostName)

throws UnknownHostException

ThegetLocalHost( )method simply returns theInetAddressobject that represents the local

host. ThegetByName( )method returns anInetAddressfor a host name passed to it. If these

methods are unable to resolve the host name, they throw anUnknownHostException.

Chapter 20: Networking 601