Servlet Life Cycle

title: Servlet Life Cycle description: Servlet ka lifecycle - init, service, destroy

Servlet Class Load ↓ init() — Ek baar, first request par ↓ service() — Har request par (doGet/doPost call karta hai) ↓ destroy() — Servlet unload hone par

Life Cycle Methods

java exampleWoHoTech

@WebServlet("/lifecycle")
public class LifeCycleServlet extends HttpServlet {

    @Override
    public void init() throws ServletException {
        // One-time initialization
        System.out.println("Servlet initialized");
        // DB connection pool, config loading, etc.
    }

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse res)
            throws ServletException, IOException {
        // Called for every request
        // Internally calls doGet/doPost/etc. based on HTTP method
        super.service(req, res); // Routes to doGet/doPost
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse res)
            throws ServletException, IOException {
        res.getWriter().println("GET request handled");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse res)
            throws ServletException, IOException {
        res.getWriter().println("POST request handled");
    }

    @Override
    public void destroy() {
        // Cleanup — close connections, release resources
        System.out.println("Servlet destroyed");
    }
}

Single Instance, Multiple Threads

Container ek hi Servlet instance rakhta hai, multiple threads service() call karte hain. Isliye Servlet thread-safe nahi hoti by default — instance variables use mat karo.

title: Servlet Life Cycle description: Servlet ka lifecycle - init, service, destroy

Servlet Class Load ↓ init() — Ek baar, first request par ↓ service() — Har request par (doGet/doPost call karta hai) ↓ destroy() — Servlet unload hone par

Life Cycle Methods

java exampleWoHoTech

@WebServlet("/lifecycle")
public class LifeCycleServlet extends HttpServlet {

    @Override
    public void init() throws ServletException {
        // One-time initialization
        System.out.println("Servlet initialized");
        // DB connection pool, config loading, etc.
    }

    @Override
    protected void service(HttpServletRequest req, HttpServletResponse res)
            throws ServletException, IOException {
        // Called for every request
        // Internally calls doGet/doPost/etc. based on HTTP method
        super.service(req, res); // Routes to doGet/doPost
    }

    @Override
    protected void doGet(HttpServletRequest req, HttpServletResponse res)
            throws ServletException, IOException {
        res.getWriter().println("GET request handled");
    }

    @Override
    protected void doPost(HttpServletRequest req, HttpServletResponse res)
            throws ServletException, IOException {
        res.getWriter().println("POST request handled");
    }

    @Override
    public void destroy() {
        // Cleanup — close connections, release resources
        System.out.println("Servlet destroyed");
    }
}

Single Instance, Multiple Threads

Container ek hi Servlet instance rakhta hai, multiple threads service() call karte hain. Isliye Servlet thread-safe nahi hoti by default — instance variables use mat karo.

Servlet Life Cycle

Life Cycle Methods

Single Instance, Multiple Threads

Continue learning this concept

Servlet Life Cycle

Life Cycle Methods

Single Instance, Multiple Threads

Continue learning this concept