Scriptlets

A JSP scriptlet is used to contain any code fragment that is valid for the scripting language used in a page. The syntax for a scriptlet is as follows: 

<%
  scripting language statements
%>

When the scripting language is set to java, a scriptlet is transformed into a Java programming language statement fragment and is inserted into the service method of the JSP page's servlet. A programming language variable created within a scriptlet is accessible from anywhere within the JSP page.

In the web service version of the hello1 application, greeting.jsp contains a scriptlet to retrieve the request parameter named username and test whether it is empty. If the if statement evaluates to true, the response page is included. Because the if statement opens a block, the HTML markup would be followed by a scriptlet that closes the block. 

<%
  String username = request.getParameter("username");
  if ( username != null && username.length() > 0 ) {
%>
  <%@include file="response.jsp" %>
<%
  }
%>