A Comprehensive Guide to Servlet and JSP

  • By Shekhar Dabe
  • March 25, 2025
  • JAVA
A Comprehensive Guide to Servlet and JSP

A Comprehensive Guide to Servlet and JSP

Java remains one of the most widely used programming languages for web development, offering powerful tools such as Servlets and JavaServer Pages (JSP). These technologies enable developers to create scalable, interactive, and dynamic web applications. Explore A Comprehensive Guide to Servlet and JSP to learn core concepts, architecture, and best practices for building dynamic web applications with Java.

This guide provides an in-depth understanding of Servlets and JSP, covering their working principles, differences, benefits, and real-world applications.

 

Understanding Servlets

A Servlet is a Java-based web component that runs on a server, processes client requests, and generates dynamic responses. Servlets are commonly used for handling backend logic in web applications.

 

Key Features of Servlets

  • Platform Independence – Runs on any server supporting Java.
  • Multithreading Support – Handles multiple requests efficiently.
  • Security – Provides built-in authentication, session management, and data protection.
  • Extensibility – Can be integrated with Java frameworks for enhanced functionality.

 

Servlet Lifecycle

  1. Loading and Instantiation – The web container loads the servlet class.
  2. Initialization (init method) – Executes once when the servlet starts.
  3. Request Handling (service method) – Processes HTTP requests like GET and POST.
  4. Destruction (destroy method) – Executes before shutting down the servlet.

 

Example: A Simple Servlet

Below is an example of a simple Java servlet that responds with a welcome message.

import java.io.IOException;
import java.io.PrintWriter;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

@WebServlet(“/WelcomeServlet”)
public class WelcomeServlet extends HttpServlet {
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType(“text/html”);
        PrintWriter out = response.getWriter();
        out.println(“<h1>Welcome to Java Servlets!</h1>”);
    }
}

 

Understanding JSP

JavaServer Pages (JSP) allow developers to embed Java code within HTML, making it easier to create dynamic web pages. JSP acts as an alternative to servlets for handling the presentation layer of an application.

Key Features of JSP

  • Separation of Concerns – Keeps Java code separate from HTML structure.
  • Simplified Development – Reduces boilerplate code compared to servlets.
  • Predefined Objects – Provides built-in objects like request, response, and session.
  • Tag-Based Approach – Uses JSP tags to generate dynamic content.

 

JSP Lifecycle

  1. Translation – Converts the JSP file into a servlet.
  2. Compilation – Compiles the generated servlet into a Java class.
  3. Class Loading & Instantiation – Loads the servlet into memory.
  4. Initialization (jspInit method) – Executes when the JSP page initializes.
  5. Execution (_jspService method) – Handles client requests dynamically.
  6. Destruction (jspDestroy method) – Runs before the JSP page is removed.

 

Example: A Simple JSP Page

<%@ page language=”java” contentType=”text/html; charset=UTF-8″ pageEncoding=”UTF-8″ %>
<!DOCTYPE html>
<html>
<head>
    <title>JSP Example</title>
</head>
<body>
    <h1>Welcome to JSP!</h1>
    <% out.println(“Current Time: ” + new java.util.Date()); %>
</body>
</html>

 

Servlet vs. JSP: Key Differences

Feature Servlet JSP
Type Java class HTML page with embedded Java
Complexity More coding required Easier to manage
Performance Faster execution Slightly slower due to extra processing
Best Used For Business logic and backend processing UI development
Maintenance Harder due to pure Java Easier due to HTML separation

 

Conclusion

Servlets and JSP remain essential for Java web development. Servlets manage backend logic, while JSP simplifies UI development. Together, they create dynamic, scalable, and maintainable web applications.

Although modern frameworks like Spring Boot have simplified web development, understanding servlets and JSP is fundamental for any Java developer working with web applications.

 

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Author:-

Shekhar Dabe

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