Life cycle of Servlet

The life cycle of a servlet can be categorized into four parts:

1. Loading and Inatantiation: The servlet container loads the servlet during startup or when the first request is made. The loading of the servlet depends on the attribute <load-on-startup> of web.xml file. If the attribute <load-on-startup> has a positive value then the servlet is load with loading of the container otherwise it load when the first request comes for service. After loading of the servlet, the container creates the instances of the servlet.
   
2. Initialization: After creating the instances, the servlet container calls the init() method and passes the servlet initialization parameters to the init() method. The init() must be called by the servlet container before the servlet can service any request. The initialization parameters persist untill the servlet is destroyed. The init() method is called only once throughout the life cycle of the servlet.
   
   The servlet will be available for service if it is loaded successfully otherwise the servlet container unloads the servlet.
   
3. Servicing the Request: After successfully completing the initialization process, the servlet will be available for service. Servlet creates seperate threads for each request. The sevlet container calls the service() method for servicing any request. The service() method determines the kind of request and calls the appropriate method (doGet() or doPost()) for handling the request and sends response to the client using the methods of the response object.
   
4. Destroying the Servlet: If the servlet is no longer needed for servicing any request, the servlet container calls the destroy() method . Like the init() method this method is also called only once throughout the life cycle of the servlet. Calling the destroy() method indicates to the servlet container not to sent the any request for service and the servlet  releases all the resources associated with it. Java Virtual Machine claims for the memory associated with the resources for garbage collection.

  Life Cycle of a Servlet 

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Comments

Paul
August 12, 2011
Thanks

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helpful topic. Before working with servlet, each of us should know it precisely. Otherwise various unwanted circumstance may occur.

Rinku
February 20, 2012
about sevlets

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no comment

kalai
October 14, 2011
good

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useful to us

thi
January 19, 2012
reply

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short and qute

satish
February 18, 2012
satish

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hi this is satish .thanks for the article .

satish
February 18, 2012
nice tutorial

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can you please explain the difference between context and container

sravan
March 10, 2012
servlet

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when we send a request then it creates an object that is requests & response objects plz tell me i am in confusion

sharath babu
April 27, 2012
life cycle of servlet

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please explain the concepts of init and destroy in detail

ramya
June 5, 2012
feedback

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this metirial is very good and easy to understand.thank u for providing this type of metirial.

kulvant singh
August 27, 2012
Ask question

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why are servlet's service method abstract

sagar thoriya
September 23, 2012
servlet

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good explain..

anynomous
October 18, 2012
anynomous

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hi

shruthi
December 31, 2012
Nice Explanation

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Hi there, Really ur explanation was very nice:) and easily understable. Thanks and regards, Shruthi

jay raghav
April 13, 2013
interface creation

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sir, give me a small code of java interface how i will i crete a intrface in java and give me short note on java how it will work in compile time also tell me about java i/o thnks