JSP API

An API is a collection of packages, classes, interfaces and sub-packages.

The JSP API consists of two packages;

·         javax.servlet.jsp

·         javax.servlet.jsp.tagext

javax.servlet.jsp package

The javax.servlet.jsp package has two interfaces and some classes.
Interfaces are

·         JspPage

·         HttpJspPage

Classes are

·         JspWriter

·         JspError

·         PageContext

·         JspFactory

·         JspEngineInfo

·         JspException

JspPage Interface

JspPage interface has provided two lifecycle methods.

public void jspInit(): This method is invoked only once during the life cycle of the JSP when first request is come to JSP page is requested. It is used to perform initialization. This method is same as the init() method of Servlet

public void jspDestroy(): This method is invoked only once during the life cycle of the JSP before the JSP page is destroyed.

HttpJspPage interface

HttpJspPage interface provided a single life cycle method called _jspService().

public  void _jspService(): This method is invoked each time when request for the JSP page comes to the container. It is used to process the request. The underscore _ signifies that you cannot override this method.