A JSP page services requests as a servlet. Thus, the life cycle and many of the capabilities of JSP pages (in particular the dynamic aspects) are determined by Java Servlet technology. The life-cycle methods of the JSP are:
jspInit(): The container calls the jspInit() to initialize the servlet instance. It is called before any other method, and is called only once for a servlet instance.
_jspService(): The container calls the _jspService() for each request and it passes the request and the response objects. _jspService() method cann?t be overridden.
jspDestroy(): The container calls this when its instance is about to destroyed.
The jspInit() and jspDestroy() methods can be overridden within a JSP page.
These methods are generated after JSP page translated and compiled, the JSP pages's servlet follows the servlet life-cycle:
If an instance of the JSP page's servlet does not exist, the container
Loads the JSP page's servlet class
Instantiates an instance of the servlet class
Initializes the servlet instance by calling the jspInit method
The container invokes the _jspService method, passing request and response objects.
If the container needs to remove the JSP page's servlet, it calls the jspDestroy method.