How to Create a Servlet Class Using HttpServlet – Beginner Guide

Introduction

After understanding what a Servlet is and setting up Tomcat, the next important step is creating a Servlet class.

In Java web development, most servlets are created by extending the HttpServlet class.
This lesson explains:

  • What HttpServlet is

  • Why we extend it

  • How to create a servlet class step by step

  • How browser requests reach your servlet

This guide assumes no prior servlet coding experience.

What Is HttpServlet?

Simple Definition:

HttpServlet is a predefined Java class provided by the Servlet API that helps you handle HTTP requests and responses.

In simple words:

HttpServlet gives you ready-made methods to handle browser requests like GET and POST.

Why Do We Extend HttpServlet?

You extend HttpServlet because it already:

  • Implements the Servlet interface

  • Handles low-level protocol details

  • Provides easy-to-use methods like:

    • doGet()

    • doPost()

Beginners should never implement Servlet directly.

Basic Syntax to Create a Servlet Class

public class MyServlet extends HttpServlet {
    // Servlet code here
}

Explanation:

  • extends HttpServlet → Makes the class a servlet

  • Your class now becomes capable of handling HTTP requests

Required Imports (Very Important)

Before writing servlet logic, import required packages:

import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.ServletException;
import java.io.IOException;

These classes come from the Servlet API.

Creating Your First Servlet Class

package com.example.servlet;

import java.io.IOException;
import java.io.PrintWriter;

import jakarta.servlet.ServletException;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;

public class HelloServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request,
                         HttpServletResponse response)
                         throws ServletException, IOException {

        response.setContentType("text/html");
        PrintWriter out = response.getWriter();

        out.println("<h1>Hello! This is my first Servlet.</h1>");
    }
}

Understanding Each Part of the Servlet Code

extends HttpServlet

  • Converts your Java class into a Servlet

  • Enables HTTP handling

doGet() Method

protected void doGet(HttpServletRequest request,
                     HttpServletResponse response)

  • Called when browser sends a GET request

  • Automatically invoked by Tomcat

  • You never call it manually

HttpServletRequest

Used to:

  • Read request data

  • Access URL parameters

  • Get session information

Example:

request.getParameter("name");

HttpServletResponse

Used to:

  • Send data back to browser

  • Set content type

  • Redirect requests

Example:

response.setContentType("text/html");

PrintWriter

Used to:

  • Write output to browser

PrintWriter out = response.getWriter();
out.println("Hello World");

Handling Different HTTP Methods

GET Request

protected void doGet(...) { }

POST Request

protected void doPost(...) { }

Use:

  • doGet() → for reading/displaying data

  • doPost() → for submitting form data

Mapping the Servlet to a URL

Using Annotation (Recommended)

@WebServlet("/hello")
public class HelloServlet extends HttpServlet {
}

Access URL:

http://localhost:8080/YourApp/hello

How the Servlet Class Works Internally

Browser Request
      ↓
Tomcat Server
      ↓
HttpServlet
      ↓
doGet() / doPost()
      ↓
Response Sent Back

Tomcat controls everything behind the scenes.

Real-Life Analogy

Think of a Reception Desk 

  • Browser → Visitor

  • HttpServlet → Receptionist

  • doGet/doPost → Types of requests

  • Response → Reply given to visitor

The receptionist knows how to handle requests properly.

Best Practices for Beginners

  • Always extend HttpServlet
  • Keep servlet logic simple
  • Use annotations for mapping
  • Separate business logic from servlet
  • Follow proper naming conventions