Life Cycle of a JSP Page

                           When a jsp is accessed for the first time, the server is slower in responding. This is because, every jsp page must be converted into an instance of a servlet class before it can be used to service client requests. For each request, the JSP engine checks the time stamps of the source JSP page and the corresponding Servlet class file to determine if the jsp page and the corresponding servlet class file to determine if the jsp page is new or if it has already been converted into class file. Therefore, if we modify a JSP page, the whole process of converting the JSP page into servlet is performed again. The process consists of the following phases known as life cycle phases.

o   Page Translation

o   Page Compilation

o   Generated Servlet class loading

o   Servlet instantiation phase

o   Calling jspInit() known as initialization phase

o   Calling _jspService() known as servicing phase

o   Calling jspDestroy() known as destruction phase

Translation phase: During this phase , the jsp engine reads the hsp page, parses it and validates the syntax of the tags, once the validations are completed, the engine creates the java source code that contains public servlet class.

Compilation phase: In this phase, the java compilation unit generated in the previous phases is compiled. The result of this compilation is the class file of the container generated servlet.

Instantiation phase:- The serlvet class is loaded dynamically and the servlet engine creates the servlet instance.

Life cycle methods of ajsp: container generated servlet implements  javax.servlet.Servlet interface. jspPage interface declares 2 methods.

            JspInit()

            JspDestroy()

HttpJspPage interface declares one method that serves the Http Client requests.

            jspServlice()

These methods are known as life cycle methods of a Jsp.

Initialization Phase: The container calls this method to initialize the servlet instance.

Servicing Phase:- In this phase _jspService() method is called by the container every time request  comes to the jsp.

Destruction Phase:- Whe the container is instructed to take the servlet instance out of service, before the instance is sent for garbase collection, container calls the life cycle method jspDestroy().

     please see for better understanding some people may read or some people may see better understanding that's the reason i am giving every post one video. at least you can see the following video you can understand better way of this post.

Please click this link Life Cycle of JSP page