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Responding to the request

The headers should include content type and encoding. The content type must be set before the writer is accessed.

This servlet constructs and returns a simple HTML file containing formatted text. Listing 4 shows the use of setContentType method of the response object to set the content type being returned before accessing the writer. Then the getWriter method of the response object is used to get access to the output stream.

Listing 4 - Preparing to return a response.
res.setContentType("text/html"); PrintWriter out = res.getWriter()

You will need to do some research on your own to learn about the different content types that can be returned by a servlet.

The PrintWriter object referred to by out is used to construct output text in Listing 5 .

Construct and return an HTML file

That brings us to the fragment in Listing 5 , which constructs and returns the various elements of an HTML page and then terminates the doGet method.

Listing 5 - Construct and return an HTML file.
out.println("<html>"); out.println("<head><title>Servlet01</title></head>"); out.println("<body>");out.println("<h1 align=\"center\">" +"<font color=\"#FF0000\">"); out.println("Hello Big Red World");out.println("</font></h1>"); out.println("</body></html>"); }//end doGet()}//end class Servlet01

Constructing the HTML code

The code in Listing 5 constructs a series of String objects and passes them as parameters to the println method of the PrintWriter object referred to by out . The content of the String objects is raw HTML code.

A tedious process:

Constructing raw HTML code as a series of Java String objects can be a very tedious and error-prone process, due particularlyto the frequent need to use the backslash escape character for quotation marks inside the strings. (All attribute values in HTML must be surrounded by quotation marks.)

This is one of the arguments for the use of JSP that you learned about in the prerequisite course .. One of the benefits of JSP is that it can greatly reduce the amount of raw HTML code that you mustconstruct to send back a typical HTML web page.

If you have written any raw HTML code, you will probably recognize the construction of the HTML code in Listing 5 (and you may also recognize the HTML code as being vintage 1999 when the servlet program waswritten) .

If you haven't written any HTML, you will need to do a little research on your own to learn about the various parts of an HTML page. At this level, it is fairly simple.

(An HTML element often consists of text content surrounded by opening and closing tags of a particular type. Elements can also be nested inside of otherelements creating a hierarchical tree of elements.)

The content between the opening and closing body tags in Listing 5 represents the real information content of the page. The rest is mostly formatting information.

This body content in Listing 5 says to

  • Set the text to style h1 (which is a maximum size header).
  • Center it on the page.
  • Set the color to hexadecimal FF0000, which is the color value for pure red (in a red, green, blue color system) .

Questions & Answers

find the 15th term of the geometric sequince whose first is 18 and last term of 387
Jerwin Reply
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
how do they get the third part x = (32)5/4
kinnecy Reply
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
Commplementary angles
Idrissa Reply
hello
Sherica
im all ears I need to learn
Sherica
right! what he said ⤴⤴⤴
Tamia
hii
Uday
what is a good calculator for all algebra; would a Casio fx 260 work with all algebra equations? please name the cheapest, thanks.
Kevin Reply
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?
Kim
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
Al
y=10×
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
how do you translate this in Algebraic Expressions
linda 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
what's the easiest and fastest way to the synthesize AgNP?
Damian Reply
China
Cied
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
Porter
many many of nanotubes
Porter
what is the k.e before it land
Yasmin
what is the function of carbon nanotubes?
Cesar
I'm interested in nanotube
Uday
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
AMJAD
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
good afternoon madam
AMJAD
what is system testing
AMJAD
what is the application of nanotechnology?
Stotaw
In this morden time nanotechnology used in many field . 1-Electronics-manufacturad IC ,RAM,MRAM,solar panel etc 2-Helth and Medical-Nanomedicine,Drug Dilivery for cancer treatment etc 3- Atomobile -MEMS, Coating on car etc. and may other field for details you can check at Google
Azam
anybody can imagine what will be happen after 100 years from now in nano tech world
Prasenjit
after 100 year this will be not nanotechnology maybe this technology name will be change . maybe aftet 100 year . we work on electron lable practically about its properties and behaviour by the different instruments
Azam
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
Prasenjit
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
Damian
silver nanoparticles could handle the job?
Damian
not now but maybe in future only AgNP maybe any other nanomaterials
Azam
Hello
Uday
I'm interested in Nanotube
Uday
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
Prasenjit
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
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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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