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(This may not make you popular with the server administrator because it could cause your single-threaded servlet to become a bottleneck.)

The third stage

The third and last stage of a servlet's life cycle is removal. When a server removes a servlet, it runs the servlet's destroy method. This method is run only once. The server will not run it again until after it reloads and reinitializes the servlet. When the destroy method runs, other threads might be running service requests. If it is necessary to access shared resources while doing cleanup, that access should be synchronized.

The javax.servlet.Servlet interface

Servlets must implement the javax.servlet.Servlet interface. For writing servlets that run under control of servers that use the HTTP protocol, the most common way to write servlets is to extend the javax.servlet.http.HttpServlet class which is a way to indirectly implement the Servlet interface.

The HttpServlet class implements the Servlet interface by extending the GenericServlet base class, and provides a framework forhandling the HTTP protocol.

Four methods

For servlets that extend the HttpServlet class, the following four methods may be overridden to cause your servlet to interact with the client.

  • doGet - for handling GET, conditional GET and HEAD requests
  • doPost - for handling POST requests
  • doPut - for handling PUT requests
  • doDelete - for handling DELETE requests

You may need to do some outside research on the HTTP protocol to learn about the nature of each type of client request listed above. You may also want to go back and review Java4350: Form Processing with JSP for information regarding the differences between the HTML GET and POST methods.

By default, if called but not overridden, these methods return a BAD_REQUEST (400) error.

The servlet discussed earlier used the doGet method to handle GET requests.

Differences between doGet and doPost

I will describe a couple of differences between the two methods that you may find useful. Assume there is a servlet named Java4550a on a localhost web server. You can execute that servlet by typing the followingaddress into the address field of the browser and pressing the Enter key :


First consider the contents of the browser's address window. When an HTML page calls the doGet method of a servlet named Java4550a , you will often see something like the following in the address window:


As you can see, some information has been appended onto the end of the address with the ? character being used to separate the two.

However, if the HTML page calls the doPost method of the same servlet, this is what you should see:


(Note that some browsers don't display the http:// portion of the address.)

In other words, with the doPost method, no visible information is appended onto the actual address as is the case with the doGet method.

It is probably also safe to say that the doGet method is the default. By this, I mean that if you enter address given above into the browser's address field and press the Enter key, the doGet method (and not the doPost method) belonging to the servlet named Java4550a will be called.

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
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?
okay, so you have 6 raised to the power of 2. what is that part of your answer
I don't understand what the A with approx sign and the boxed x mean
it think it's written 20/(X-6)^2 so it's 20 divided by X-6 squared
I'm not sure why it wrote it the other way
I got X =-6
ok. so take the square root of both sides, now you have plus or minus the square root of 20= x-6
oops. ignore that.
so you not have an equal sign anywhere in the original equation?
is it a question of log
Commplementary angles
Idrissa Reply
im all ears I need to learn
right! what he said ⤴⤴⤴
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?
The answer is neither. The function, 2 = 0 cannot exist. Hence, the function is undefined.
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
types of nano material
abeetha Reply
I start with an easy one. carbon nanotubes woven into a long filament like a string
many many of nanotubes
what is the k.e before it land
what is the function of carbon nanotubes?
I'm interested in nanotube
what is nanomaterials​ and their applications of sensors.
Ramkumar Reply
what is nano technology
Sravani Reply
what is system testing?
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
what is system testing
what is the application of nanotechnology?
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
anybody can imagine what will be happen after 100 years from now in nano tech world
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
name doesn't matter , whatever it will be change... I'm taking about effect on circumstances of the microscopic world
how hard could it be to apply nanotechnology against viral infections such HIV or Ebola?
silver nanoparticles could handle the job?
not now but maybe in future only AgNP maybe any other nanomaterials
I'm interested in Nanotube
this technology will not going on for the long time , so I'm thinking about femtotechnology 10^-15
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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