Directives:
Directives provide general information about the JSP page to the JSP engine. There are three types of directives: page, include, and taglib.
A page directive informs the engine about the overall properties of a JSP page. For example, the following page directive informs the JSP engine that we will be using Java as the scripting language in our JSP page:
<%@ page language="java" %>An include directive tells the JSP engine to include the contents of another file (HTML, JSP , etc.) in the current page. Here is an example of an include directive:
<%@ include file="copyright.html" %>A taglib directive is used for associating a prefix with a tag library. The following is an example of a taglib directive:
<%@ taglib prefix="test" uri="taglib.tld" %>Declarations:
Declarations declare and define variables and methods that can be used in the JSP page.
The following is an example of a JSP declaration:
<%! int count = 0; %>
This declares a variable named count and initializes it to 0. The variable is initialized only once when the page is first loaded by the JSP engine, and retains its value in sub-sequent client requests. That is why the count variable in listing 10.1 is not reset to 0 each time we access the page.
A declaration always starts with <%! and ends with %>. It can contain any number of valid Java declaration statements. For example, the following tag declares a variable and a method in a single tag:
<%!
String color[] = {"red", "green", "blue"};
String getColor(int i)
{
return color[i];
}
%>JSP Interview Questions
