What are the phases of the servlet lifecycle?

The servlet lifecycle includes initialization ( init() ), request handling ( service() ), and destruction ( destroy() ).

What method is used to handle client requests in a servlet?

The service() method is used to handle client requests.

Explain the Lifecycle of a Servlet | FullStackPrep.Dev

💡 Concept: Servlet Lifecycle

The lifecycle of a servlet is managed by the servlet container and consists of several phases such as initialization, request handling, and destruction.

📘 Quick Intro

The servlet lifecycle is the process a servlet undergoes from its creation to its destruction. The key phases of a servlet lifecycle are init(), service(), and destroy().

🧠 Analogy

Think of a servlet as a restaurant waiter. The init() method prepares the waiter for service, the service() method handles customer requests, and the destroy() method cleans up before the waiter leaves at the end of the shift.

🔧 Technical Explanation

init(): This method is called once when the servlet is first loaded. It is used to initialize resources like database connections.
service(): This method is called to handle each client request. It processes HTTP requests (like doGet() and doPost()) based on the type of request.
destroy(): This method is called when the servlet is being destroyed. It is used to release any resources acquired by the servlet.
The servlet container manages the lifecycle, which ensures that the servlet is created, initialized, and destroyed in a controlled way.

🎯 Use Cases

✅ Servlets are used in web applications to handle requests and responses.
✅ Commonly used in Java-based web frameworks like Java EE (Jakarta EE) and Spring MVC.
✅ Useful in web servers for session management and database interaction.

💻 Example: Servlet Lifecycle


import java.io.*;
import javax.servlet.*;
import javax.servlet.http.*;

public class MyServlet extends HttpServlet {
    @Override
    public void init() throws ServletException {
        System.out.println("Servlet Initialized");
    }

    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.getWriter().println("Hello, this is the doGet method!");
    }

    @Override
    public void destroy() {
        System.out.println("Servlet Destroyed");
    }
}

❓ Interview Q&A

Q1: What are the main phases of a servlet lifecycle?
A: The servlet lifecycle has three main phases: initialization (init()), request handling (service()), and destruction (destroy()).

Q2: What happens in the init() method?
A: The init() method initializes the servlet and sets up any resources required for processing requests, such as database connections.

Q3: How does the servlet handle requests?
A: The service() method handles incoming client requests by calling specific methods like doGet() or doPost().

Q4: What happens when the servlet is destroyed?
A: The destroy() method is called, allowing the servlet to release resources and perform cleanup tasks.

Q5: How is the servlet lifecycle managed?
A: The servlet container (such as Tomcat) manages the lifecycle by loading, initializing, and destroying the servlet.

Q6: Can a servlet be initialized multiple times?
A: No, a servlet is initialized only once during the first request it receives unless the servlet container is restarted.

Q7: How can you configure a servlet?
A: Servlets can be configured using web.xml or annotations like @WebServlet in Java EE applications.

Q8: Can you have multiple servlets in a web application?
A: Yes, you can have multiple servlets, each handling different types of requests or providing different functionalities.

Q9: What is the role of the servlet container?
A: The servlet container manages the lifecycle of servlets, including their creation, initialization, request handling, and destruction.

Q10: What is the doGet() method used for?
A: The doGet() method handles HTTP GET requests, typically used to retrieve information from the server.

📝 MCQs

Q1. What is the first phase in the lifecycle of a servlet?

Request handling
Initialization (<code>init()</code>)
Destruction (<code>destroy()</code>)
Service handling

Q2. What does the <code>service()</code> method do?

Handles the client request
Initializes resources
Destroys the servlet
Runs in the background

Q3. What method is called to destroy a servlet?

init()
doGet()
destroy()
service()

Q4. Can the <code>init()</code> method be called multiple times?

Yes
No, it is called once when the servlet is loaded
Only on first request
Only if servlet is reloaded

Q5. What is the role of the servlet container?

Manages session data
Manages the lifecycle of servlets
Runs the servlet code
Generates HTTP responses

Q6. What happens after the servlet is initialized?

The servlet is destroyed
The servlet is ready to handle client requests
The servlet is reloaded
The servlet enters idle state

Q7. Which method handles HTTP GET requests?

doPost()
doGet()
service()
init()

Q8. What happens when the servlet is destroyed?

It stops serving requests
The <code>destroy()</code> method is called to release resources
The servlet is unloaded from memory
The servlet continues running

Q9. Can a servlet be destroyed manually?

No
Yes, by calling <code>destroy()</code> from the servlet container
Yes, by using <code>service()</code>
Only when the server is restarted

Q10. Which method is called for each client request?

init()
service()
doGet()
destroy()

💡 Bonus Insight

The servlet lifecycle is crucial for understanding how servlets are managed by the servlet container. This knowledge is important when working with Java EE (Jakarta EE) applications or Spring MVC.

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Explain the Lifecycle of a Servlet