Uses of JSP Constructs

Scripting elements calling 

Simple

servlet code directly

Application

Scripting elements calling 

servlet code indirectly (by 

means of utility classes)

Beans

Custom tags

Complex

Servlet/JSP combo 

Application

(MVC architecture)

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Review: Calling Java Code 

Directly: JSP Scripting Elements

JSP Expressions

Format: 

<%= expression %>

Evaluated and inserted into the servlet's output. 

JSP Scriptlets

Format: 

<% code %>

Inserted verbatim into the _jspService method 

JSP Declarations

Format: 

<%! code %>

Inserted verbatim into the body of the servlet class

Predefined variables

request, response, out, session, application

Limit the Java code in page

Use helper classes, beans, custom tags, servlet/JSP combo

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