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Explanation

A Servlet is a Java component that runs on a web server and handles client requests to generate dynamic responses.

Code:

Browser
   |
   | HTTP Request
   v
Web Server / Servlet Container
   |
   v
Servlet
   |
   | HTTP Response
   v
Browser

Explanation

The Servlet container such as Tomcat manages the servlet lifecycle, request routing, threading, and communication with the servlet.

Code:

Client
  |
  v
Apache Tomcat
  |
  +--> Servlet 1
  +--> Servlet 2
  +--> Servlet 3

Explanation

Create a servlet by extending HttpServlet and map it to a URL using the @WebServlet annotation.

Code:

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

    protected void doGet(HttpServletRequest req,
                         HttpServletResponse resp) {
        // Handle request
    }
}

Explanation

The servlet container receives the HTTP request and invokes the appropriate servlet method based on the HTTP method and URL.

Code:

GET /hello
      |
      v
Tomcat
      |
      v
HelloServlet.doGet()
      |
      v
HTTP Response

Explanation

Servlets are commonly used as the controller layer in traditional Java web applications.

Code:

Browser
   |
   v
Servlet Controller
   |
   +---- Service
   |
   +---- DAO
   |
   v
Database