Java Servlet Life Cycle

Java Servlet Life Cycle

Today I am discussing about Java servlet life cycle . Servlets run on server as a same part or process of web server but all the task (Initializing ,invoking ,destroying) performed by web server.

The main three methods to communicate with servlet are:

1.init()

2.service()

3.destroy()

Ancillary methods are:

1.getServletConfig ()

2.getServletinfo()

Details of the mentioned methods:

1.init () Method: Init() method is invoked at the start when a servlet is loaded for first time .Init() method works like a introductory ,Init() method perform setup processes like establishing connections with web servers .Init () has one argument, a reference to a ServletConfig object which provides  initialization arguments for the servlet.

2.Service () Method :The main functional method in servlet life cycle is Service() method .When client sent request to server the Service() method listen it and give response for each request .Service method takes two parameters:

ServletRequest and ServletResponse.A ServletRequest object gets data from the client.ServletResponse gives response of ServletRequest. When preparing a response, the method setCotenType () is called first to set the MIME type of the reply. Next, the method getoutputStream () or getWriter () can be used to obtain a ServletOutputStream or PrintWriter, respcitively, to send data back to the client.

3.Destory () Method :Main function of Destroy () method is to clean up any resources (like open files or db connections) before the servlet is unloaded .If there is no clean-up operations, Destroy() method can be an empty method .Destroy() method is invoked when all the service request is completed or task timing is over .So if service method is running Destroy() method can not perform its operation.