doGet() vs doPost() in Servlets – Key Differences Explained Simply

Introduction

When working with Java Servlets, two methods appear again and again:

  • doGet()

  • doPost()

Beginners often feel confused about:

  • When to use doGet()

  • When to use doPost()

  • How they actually differ

This guide explains doGet() vs doPost() from the basics, using simple language, examples, tables, and real-life analogies, so it can fully replace a live classroom explanation.

What Are doGet() and doPost()?

Simple Definition

  • doGet() handles HTTP GET requests

  • doPost() handles HTTP POST requests

Both methods are defined in the HttpServlet class and are automatically called by the Servlet container (Tomcat).

What Is an HTTP Request?

An HTTP request is sent by the browser to the server when:

  • A URL is typed

  • A link is clicked

  • A form is submitted

Two common request methods are:

  • GET

  • POST

Servlets handle these using doGet() and doPost().

doGet() Method Explained

Purpose

doGet() is used to:

  • Retrieve data

  • Display information

  • Handle requests that do not change server data

Method Signature

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

Example: doGet()

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

    response.getWriter().println("This is a GET request");
}

Characteristics of doGet()

  • Data is sent through the URL

  • Parameters are visible

  • Limited data size

  • Can be bookmarked

  • Less secure

Example URL:

/login?username=admin

doPost() Method Explained

Purpose

doPost() is used to:

  • Submit form data

  • Send sensitive information

  • Modify server data (insert, update, delete)

Method Signature

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

Example: doPost()

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

    response.getWriter().println("This is a POST request");
}

Characteristics of doPost()

  • Data is sent in request body

  • Parameters are hidden

  • No size limitation (practically)

  • Cannot be bookmarked

  • More secure than GET

How Browser Decides Between doGet() and doPost()

HTML Form Example

<form action="login" method="get">
    <input type="text" name="user">
    <button type="submit">Login</button>
</form>

Calls doGet()

<form action="login" method="post">
    <input type="text" name="user">
    <button type="submit">Login</button>
</form>

Calls doPost()

 

The method attribute decides which servlet method runs.

doGet() vs doPost() – Comparison Table

FeaturedoGet()doPost()
HTTP MethodGETPOST
Data LocationURLRequest body
VisibilityVisibleHidden
SecurityLowHigher
Data SizeLimitedLarge
BookmarkableYesNo
Typical UseFetch dataSubmit data

Reading Form Data (Same for Both)

Both methods use:

request.getParameter("name");

Example:

String username = request.getParameter("user");

Reading data is the same in doGet() and doPost().

Real-Life Analogy

Think of Communication 

GET

  • Writing data on a postcard

  • Anyone can read it

POST

  • Sending data in a sealed envelope

  • More private

GET = postcard
POST = sealed letter

When to Use doGet()?

Use doGet() when:

  • Displaying pages

  • Searching data

  • Fetching records

  • Navigation requests

Example:

  • Search results

  • Product listing

  • Profile view

When to Use doPost()?

Use doPost() when:

  • Submitting forms

  • Login/signup

  • Uploading data

  • Modifying database

Example:

  • Login form

  • Registration form

  • Payment processing

Best Practices

  • Use doGet() for safe, read-only operations
  • Use doPost() for sensitive or large data
  • Validate input in both methods
  • Never send passwords via GET
  • Follow RESTful conventions