Introduction to JavaServer Pages (JSP)
JavaServer Pages (JSP) is a server-side technology used to create dynamic, platform-independent web applications. It allows developers to embed Java code directly inside HTML pages using JSP tags and scripting elements.
JSP is built on top of Java Servlets and offers a simpler, template-based approach to generate dynamic content.
Why JSP?
- Easy to embed Java code into HTML
- Supports MVC architecture
- Simplifies presentation logic
- Reusable components using tags and JSTL
- Powerful backend integration using JDBC and JavaBeans
1. What is JSP?
JSP is a technology that extends Servlets and enables dynamic web page creation using Java. During execution:
- A JSP page is converted into a Servlet by the JSP engine
- The Servlet is compiled into bytecode
- The compiled Servlet generates dynamic output
JSP File Extension
.jsp
2. Basic Syntax of a JSP Page
<%@ page language="java" contentType="text/html; charset=UTF-8" %>
<html>
<body>
<h2>Welcome to JSP</h2>
Current Time: <%= new java.util.Date() %>
</body>
</html>
3. JSP vs Servlet
| Feature | Servlet | JSP |
|---|---|---|
| Programming Style | Pure Java | Java + HTML mixed |
| Best For | Business logic | Presentation layer |
| Compilation | Directly compiled | Converted to Servlet then compiled |
| Ease of Use | Harder | Simple template system |
4. Features of JSP
- Implicit Objects – Predefined objects like request, response, session, application
- Automatic Compilation – JSP is converted into Servlets automatically
- Tag-based development – using JSTL and custom tags
- Reusability – JavaBeans integration
- Scalable – integrates with JDBC, Hibernate, Spring
- Supports MVC – separates logic (Servlet) and view (JSP)
5. Life Cycle Overview
JSP lifecycle includes:
- Translation → JSP → Servlet
- Compilation → Class file
- Loading the Servlet
- Instantiation
- Initialization (
jspInit()) - Request Handling (
_jspService()) - Destroy (
jspDestroy())
Lifecycle Diagram
JSP Page ↓ (Translation) Servlet Source ↓ (Compilation) Servlet Class ↓ Loaded by Container ↓ jspInit() → _jspService() → jspDestroy()
6. Advantages of JSP
- Easy to develop dynamic web pages
- Reduces code complexity compared to Servlets
- Automatic JavaBean and JDBC integration
- Extensive tag library support
- Faster development cycle
7. Practical Example – Dynamic Greeting Page
<%@ page import="java.util.*" %>
<html>
<body>
<h2>Dynamic Greeting</h2>
<%
Date d = new Date();
out.println("Current Date & Time: " + d);
%>
</body>
</html>
Conclusion
JSP is a powerful, flexible, and easy-to-use server-side technology designed to simplify the creation of dynamic web pages. By combining HTML with Java, JSP provides a fast and efficient way to build scalable and interactive web applications.
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