There are three Scripting Elements
Expressions of the form <%= expression %> that are evaluated and inserted into the output,
A JSP expression is used to insert Java values directly into the output. It has the following form:
<%= Java expression %>
The Java expression is evaluated, converted to a string, and inserted in the page
Current time: <%= new java.util.Date() %>
predefined variables that you can use request, the HttpServletRequest; response, the HttpServletResponse; session, the HttpSession associated with the request (if any); and out, the PrintWriter (a buffered version of type JspWriter) used to send output to the client.
Example :Your hostname: <%= request.getRemoteHost() %>
2 Scriptlets of the form <% code %> that are inserted into the servlet's service method, and
If you want to do something more complex than insert a simple expression, JSP scriptlets insert code into the service() method of the generated servlet.
Scriptlets have the following form:
<% Java Code %> Scriptlets have access to the same automatically defined variables as expressions
<%
String name = request.getParameter("name");
out.println("name: " + name);
%>
3 Declarations of the form <%! code %> that are inserted into the body of the servlet class, outside of any existing methods.
A JSP declaration define methods or fields that get inserted into the main body of the servlet class (outside of the service method processing the request). It has the following form:
<%! Java Code %>
or
<%!
public int getValue(){
return 78;
}
%>
The method we can use in Expression also.
<%=getValue()%>
