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Tedious and error prone

Writing raw HTML code is not fun even under the best of circumstances. That is why I use a WYSIWYG HTML editor for authoring these modules.

Even for this very simple servlet, the process of constructing the output HTML code using Java println statements was very tedious and error prone. Much of the difficulty arises from the fact that Java strings must be enclosed inmatching double quotes and all HTML attribute values must also be enclosed in matching double or single quotes. As you can see from Listing 16 , the requirement to escape double quotes inside Java strings with the backslashcharacter can lead to some very confusing code. (I suppose it might be less confusing if I were to use single quotes instead of double quotes on HTML attributevalues. I will try that in the next module.)

In any event, the next section presents a JSP version of the same servlet. JSP intermingles HTML code with Java code and greatly reduces the amount of HTMLcode that must be constructed using Java println statements in a servlet. If you are unfamiliar with JSP, you can learn about it in the modules that begin at Java4305: Preface to JSP .

The JSP program

A complete listing of the JSP version of this program is provided in Listing 17 . I found this JSP version much easier to write than the servlet version discussed above. Admittedly, however, I wrote the servlet version first, so that probablyhelped to make it easier to write the JSP version.

I wrote all of the HTML code using Microsoft Expression Web 4, which provides both a WYSIWYG capability and a raw HTML editing capability. Once I confirmed that theHTML code was correct and valid, I went back and inserted the JSP tags containing the Java code.

As mentioned earlier, the JSP does not get and use the name of the computer on which it is running. Instead it uses the generic name localhost, which limitsthe ability to access the JSP from another computer on the network.

Interesting code fragments

Once again, I will discuss this program in fragments. A complete listing of the program is provided in Listing 17 .

Create basic web page structure

Listing 10 shows the HTML code that is roughly equivalent to the Java code in Listing 4 through Listing 7 . This code creates the HTML header and the basic structure of the web page shownin Figure 1 .

Listing 10 - Create basic web page structure.
<html><head><title>Java4550a</title></head><body><form method="get" action="http://localhost:8080/Java4550a.jsp"><p>Enter a name and press the button</p><p>Name:<input type="text" name="firstName"/></p><input type="submit" value="Submit Name"/><p>Your list of names is:<br/>

A JSP scriptlet

Listing 11 is a scriptlet containing pure Java code. It begins by getting the data from the request object. Then it deals withthe situation where nothing has been entered into the text field in Figure 1 , reporting that the list is empty. It ends with the beginning of a for loop that is executed when the array is not empty. Recall that in JSP, Java code blocks can begin in one scriptlet andend in another scriptlet later in the page. That is what is happening here.

Questions & Answers

what is math number
Tric Reply
x-2y+3z=-3 2x-y+z=7 -x+3y-z=6
Sidiki Reply
Need help solving this problem (2/7)^-2
Simone Reply
x+2y-z=7
Sidiki
what is the coefficient of -4×
Mehri Reply
-1
Shedrak
the operation * is x * y =x + y/ 1+(x × y) show if the operation is commutative if x × y is not equal to -1
Alfred Reply
An investment account was opened with an initial deposit of $9,600 and earns 7.4% interest, compounded continuously. How much will the account be worth after 15 years?
Kala Reply
lim x to infinity e^1-e^-1/log(1+x)
given eccentricity and a point find the equiation
Moses Reply
12, 17, 22.... 25th term
Alexandra Reply
12, 17, 22.... 25th term
Akash
College algebra is really hard?
Shirleen Reply
Absolutely, for me. My problems with math started in First grade...involving a nun Sister Anastasia, bad vision, talking & getting expelled from Catholic school. When it comes to math I just can't focus and all I can hear is our family silverware banging and clanging on the pink Formica table.
Carole
I'm 13 and I understand it great
AJ
I am 1 year old but I can do it! 1+1=2 proof very hard for me though.
Atone
hi
Adu
Not really they are just easy concepts which can be understood if you have great basics. I am 14 I understood them easily.
Vedant
find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
I know this work
salma
The given of f(x=x-2. then what is the value of this f(3) 5f(x+1)
virgelyn Reply
hmm well what is the answer
Abhi
If f(x) = x-2 then, f(3) when 5f(x+1) 5((3-2)+1) 5(1+1) 5(2) 10
Augustine
how do they get the third part x = (32)5/4
kinnecy Reply
make 5/4 into a mixed number, make that a decimal, and then multiply 32 by the decimal 5/4 turns out to be
AJ
how
Sheref
can someone help me with some logarithmic and exponential equations.
Jeffrey Reply
sure. what is your question?
ninjadapaul
20/(×-6^2)
Salomon
okay, so you have 6 raised to the power of 2. what is that part of your answer
ninjadapaul
I don't understand what the A with approx sign and the boxed x mean
ninjadapaul
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
Salomon
I'm not sure why it wrote it the other way
Salomon
I got X =-6
Salomon
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
ninjadapaul
oops. ignore that.
ninjadapaul
so you not have an equal sign anywhere in the original equation?
ninjadapaul
hmm
Abhi
is it a question of log
Abhi
🤔.
Abhi
I rally confuse this number And equations too I need exactly help
salma
But this is not salma it's Faiza live in lousvile Ky I garbage this so I am going collage with JCTC that the of the collage thank you my friends
salma
Commplementary angles
Idrissa Reply
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
hii
Uday
hi
salma
hi
Ayuba
Hello
opoku
hi
Ali
greetings from Iran
Ali
salut. from Algeria
Bach
hi
Nharnhar
A soccer field is a rectangle 130 meters wide and 110 meters long. The coach asks players to run from one corner to the other corner diagonally across. What is that distance, to the nearest tenths place.
Kimberly Reply
Jeannette has $5 and $10 bills in her wallet. The number of fives is three more than six times the number of tens. Let t represent the number of tens. Write an expression for the number of fives.
August Reply
What is the expressiin for seven less than four times the number of nickels
Leonardo Reply
How do i figure this problem out.
how do you translate this in Algebraic Expressions
linda Reply
why surface tension is zero at critical temperature
Shanjida
I think if critical temperature denote high temperature then a liquid stats boils that time the water stats to evaporate so some moles of h2o to up and due to high temp the bonding break they have low density so it can be a reason
s.
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
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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
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