Java Reference
In-Depth Information
CHAPTER 5
Networking
Sun Microsystems has long used the slogan “The Network is the Computer.” It's no
surprise, therefore, that they designed Java to be a network-centeric language. The
java.net package provides powerful and easy-to-use networking capabilities. The
examples in this chapter demonstrate those capabilities at a number of different
levels of abstraction. They show you how to:
Use the URL class to parse URLs and download the network resources speci-
fied by a URL
Use the URLConnection class to gain more control over the downloading of
network resources
Write client programs that use the Socket class to communicate over the net-
work
Use the Socket and ServerSocket classes to write servers
Send and receive low-overhead datagram packets
Downloading the Contents of a URL
Example 5-1 shows how you can download the network resource referred to by a
URL using the URL class. This class serves mainly to represent and parse URLs but
also has several important methods for downloading URLs. The most high-level of
these methods is getContent() , which downloads the content of a URL, parses it,
and returns the parsed object. This method relies on special content handlers hav-
ing been installed to perform the parsing. By default, the Java SDK has content
handlers for plain text and for several common image formats. When you call the
getContent() method of a URL object that refers to a plain text or GIF or JPEG
image file, the method returns a String or Image object. More commonly, when
getContent() doesn't know how to handle the data type, it simply returns an
InputStream so that you can read and parse the data yourself.
Search WWH ::




Custom Search