JSP Introduction in Java

 Introduction to JSP

 

  coding-zon-JSP-Intro

JSPHome

 

JSP's allow to design user interfaces. JSP pages used for presentation of content. Hard coding of HTML Code into Servlet, they invented the JSP.

Presentation code  embedded inside servlets. This will make web developer should have servlet knowledge. But
JSP pages  makes the flexibility in developing presentation content by
separating the  application logic from presentation logic.

JSP is converted into servlets at the time of compilation. All the code which is written in scriptlets is inserted into servlets doGet() method.

Programming in JSP.

 

JSP Elements

  1. Scripting elements 
  2. implicit objects 
  3. directives 
  4. actions 
  5. comments 
 
        <!--          -->  HTML user will use (for documentation).
        <%--          --%> script let are not visible in client output.



I. Scripting elements:

In this tutorial, you are just going to learn how to use script lets. There are 3 types of scripting elements available in JSP.


  1. script lets
  2. declarations
  3. expressions



<%    %>---> script lets → contains doGet() method java code.
<%!   %>---> declaration → variables, method declarations goes here.
<%=   %>---> expression  → mathematical expressions.
	

Examples:


<%= String var ="Welcome"; %>

<%@ page import="java.util.Date()" %>

<%! Date date = new Date(); %>

<% out.println("Date="+date.toString()); %>
 
 
 
 

First.jsp

This example just prints some message on the browser's screen.

To print messages, JSP uses out object's println method. 

out object is an implicit object.  

You will learn in detail in further tutorial about out object. 

 

- In eclipse  create a webproject with some name ex: JSPWebapp

- Right click and select new → jsp → give the name as first.jsp.

- Remove the code in it and add the code line give below..


<!DOCTYPE>
<html>
<head> 
<title>Codingzon JSP Demos</title>
</head>
<body>

<% out.println("<br>Welcome  to JSP"); %>


</body>
</html>
 
  


Save it, and run first.jsp file. You will see the output as shown in picture.


 

coding-zon-jsp-first-program


 
 
 

expressions in JSP

  
 

This example shows how to use expression. expression  is written as shown…

 
syntax: 
 
<%=  someexpression %>
 

expression does have semicolon as a line terminator

 
example:
  
<%=  (5 * 5)  %> 
 
It is converted as 
 
out.println((5*5));  
 
 

expressiondemo.jsp

 
 
<!DOCTYPE html> 
<html>
<head> 
<title>Codingzon JSP Demos</title>
</head>
<body>   
 
<%= ((5 * 5)) %>

  
</body>
</html>  
 
 
coding-zon-jsp-expressions-example2

 
 
expressiondemo2.jsp   
 
An expression with string data.
 
<!DOCTYPE html>
<html>
<head> 
<title>Codingzon JSP Demos</title>
</head>
<body>  
 
 
 <%= "<br>Hello How are you" %>

  
</body>
</html>   

coding-zon-jsp-expressions



 

declarations

 

Show declaring a variables in JSP. It can be done using 

 syntax: 
 
<%! Datatype variable = value; %>

 example:
 
<%! String str= "John"; %>
 

 

 

declarationsdemo.jsp

 
<!DOCTYPE html> 
<html>
<head> 
<title> Codingzon JSP Demos</title>
</head>
<body>


<%! String str= "John";%>
 
<%    
    out.println("<br>Hello " + str); 
 
 %>
        


</body>
</html> 

coding-zon-jsp-declarations
 


2. Scripting elements: 

Continue..

 

 




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