Introduction to JSP

Introduction

  • It stands for Java Server Pages.
  • It is a server side technology.
  • It is used for creating web application.
  • It is used to create dynamic web content.
  • In this JSP tags are used to insert JAVA code into HTML pages.
  • It is an advanced version of Servlet Technology.
  • It is a Web based technology helps us to create dynamic and platform independent web pages.
  • In this, Java code can be inserted in HTML/ XML pages or both.
  • JSP is first converted into servlet by JSP container before processing the client’s request.

JSP pages are more advantageous than Servlet:

  • They are easy to maintain.
  • No recompilation or redeployment is required.
  • JSP has access to entire API of JAVA .
  • JSP are extended version of Servlet.

Features of JSP

  • Coding in JSP is easy :- As it is just adding JAVA code to HTML/XML.
  • Reduction in the length of Code :- In JSP we use action tags, custom tags etc.
  • Connection to Database is easier :-It is easier to connect website to database and allows to read or write data easily to the database.
  • Make Interactive websites :- In this we can create dynamic web pages which helps user to interact in real time environment.
  • Portable, Powerful, flexible and easy to maintain :- as these are browser and server independent.
  • No Redeployment and No Re-Compilation :- It is dynamic, secure and platform independent so no need to re-compilation.
  • Extension to Servlet :- as it has all features of servlets, implicit objects and custom tags
  • JSP syntax

    Syntax available in JSP are following

    1. Declaration Tag :-It is used to declare variables.
    2. Syntax:- 
      <%!  Dec var  %>
      Example:-
      <%! int var=10; %>
       
    3. Java Scriplets :- It allows us to add any number of JAVA code, variables and expressions.
    4.  Syntax:- 
      <% java code %>
      
    5. JSP Expression :- It evaluates and convert the expression to a string.
    6.  Syntax:- 
      <%= expression %> 
       Example:- 
      <% num1 = num1+num2 %> 
      
    7. JAVA Comments :- It contains the text that is added for information which has to be ignored.
    8.  Syntax:- 
      <% -- JSP Comments %>
      

      Process of Execution

      Steps for Execution of JSP are following:-

      • Create html page from where request will be sent to server eg try.html.
      • To handle to request of user next is to create .jsp file Eg. new.jsp
      • Create project folder structure.
      • Create XML file eg my.xml.
      • Create WAR file.
      • Start Tomcat
      • Run Application



      Example of Hello World
      We will make one .html file and .jsp file

      demo.jsp
      <html>
      <head>
      <meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1">
      <title>Hello World - JSP tutorial</title>
      </head>
      <body>
          <%= "Hello World!" %>
      </body>
      </html>
      

      Advantages of using JSP

      • It does not require advanced knowledge of JAVA
      • It is capable of handling exceptions
      • Easy to use and learn
      • It can tags which are easy to use and understand
      • Implicit objects are there which reduces the length of code
      • It is suitable for both JAVA and non JAVA programmer

      Disadvantages of using JSP

      • Difficult to debug for errors.
      • First time access leads to wastage of time
      • It’s output is HTML which lacks features.




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