<< Chapter < Page Chapter >> Page >

A higher level approach

URL programming occurs at a higher level than socket programming, and in theory represents some very powerful ideas. The powerful ideas represented bythe advanced features of the URL class require an understanding of the development of protocol handlers and content handlers. I discussed this in somedetail in an earlier module titled Java4620: General Information , and won't repeat that discussion here.

A mundane alternative

In addition to supporting the advanced concepts discussed in the earlier module, theURL class also provides a relatively mundane alternative way to connect one computer to another and transfer data on a stream basis. This module isprimarily based on this capability.

Discussion and sample code

I will explain the programs named Java4640a and Java4640d in fragments. Complete listings of both programs are provided in Listing 8 and Listing 9 .

The program Java4640a

This program exercises four of the constructors and six of the methods of the URL class.

The program also illustrates the use of the URLEncoder class to convert a string containing spaces and other such characters into a UTF-8encoded string format.

Screen output from the program named Java4640a

The output from the program is shown in Figure 2 . I will refer to portions of this output while discussing the program.

Figure 2 - Screen output from the program named Java4640a.
Use simple string constructor for host URL http www.austincc.edu -1 nullhttp://www.austincc.edu Use simple string constructor for host plus filehttp www.austincc.edu -1 /baldwin null http://www.austincc.edu/baldwinUse strings for protocol, host, and file http www.austincc.edu -1 /baldwin nullhttp://www.austincc.edu/baldwin Use strings for protocol host, and fileand int for port http www.austincc.edu 80 /baldwin nullhttp://www.austincc.edu:80/baldwin Construct absolute URL from host URL and relative URLhttp www.austincc.edu -1 /baldwin/Index.html null http://www.austincc.edu/baldwin/Index.htmlNow use URLEncoder to create UTF-8 encoded String http://space .tilde~.plus+.comhttp%3A%2F%2Fspace+.tilde%7E.plus%2B.com

The method named display

The code in Listing 1 is a method named display that I wrote to illustrate some of the methods of the URLclass, and also to serve the practical needs of displaying information contained in a URL object.

Listing 1 - The method named display.
void display(URL url){//method to display parts of URL System.out.print(url.getProtocol() + " ");System.out.print(url.getHost() + " "); System.out.print(url.getPort() + " ");System.out.print(url.getFile() + " "); System.out.println(url.getRef());//Now display entire URL as a string.System.out.println(url.toString()); System.out.println();}//end display

This method receives a reference to a URL object as a parameter and displays its component parts separated by space characters. Then it uses the overridden toString method of the URL class to display the contents of theURL object as a single String object.

The parts of the URL

Questions & Answers

a perfect square v²+2v+_
Dearan Reply
kkk nice
Abdirahman Reply
algebra 2 Inequalities:If equation 2 = 0 it is an open set?
Kim Reply
or infinite solutions?
Embra Reply
if |A| not equal to 0 and order of A is n prove that adj (adj A = |A|
Nancy Reply
rolling four fair dice and getting an even number an all four dice
ramon Reply
Kristine 2*2*2=8
Bridget Reply
Differences Between Laspeyres and Paasche Indices
Emedobi Reply
No. 7x -4y is simplified from 4x + (3y + 3x) -7y
Mary Reply
is it 3×y ?
Joan Reply
J, combine like terms 7x-4y
Bridget Reply
im not good at math so would this help me
Rachael Reply
how did I we'll learn this
Noor Reply
f(x)= 2|x+5| find f(-6)
Prince Reply
f(n)= 2n + 1
Samantha Reply
Need to simplify the expresin. 3/7 (x+y)-1/7 (x-1)=
Crystal Reply
. After 3 months on a diet, Lisa had lost 12% of her original weight. She lost 21 pounds. What was Lisa's original weight?
Chris Reply
preparation of nanomaterial
Victor Reply
Yes, Nanotechnology has a very fast field of applications and their is always something new to do with it...
Himanshu Reply
can nanotechnology change the direction of the face of the world
Prasenjit Reply
At high concentrations (>0.01 M), the relation between absorptivity coefficient and absorbance is no longer linear. This is due to the electrostatic interactions between the quantum dots in close proximity. If the concentration of the solution is high, another effect that is seen is the scattering of light from the large number of quantum dots. This assumption only works at low concentrations of the analyte. Presence of stray light.
Ali Reply
the Beer law works very well for dilute solutions but fails for very high concentrations. why?
bamidele Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Got questions? Join the online conversation and get instant answers!
QuizOver.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Object-oriented programming (oop) with java. OpenStax CNX. Jun 29, 2016 Download for free at https://legacy.cnx.org/content/col11441/1.201
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Object-oriented programming (oop) with java' conversation and receive update notifications?