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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 variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
research.net
kanaga
sciencedirect big data base
Ernesto
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
Bharti
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
Daniel
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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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