HTTPSession Session Management

PHOTO EMBED

Fri Nov 15 2024 14:59:35 GMT+0000 (Coordinated Universal Time)

Saved by @signup_returns 

//login.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Login Page</title>
</head>
<body>
    <h2>Login Page</h2>
    <form action="LoginServlet" method="post">
        <label for="username">Enter Username:</label>
        <input type="text" id="username" name="username" required>
        <br><br>
        <input type="submit" value="Login">
    </form>
</body>
</html>


//LoginServlet.java

import java.io.IOException;
import java.io.PrintWriter;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;

@WebServlet("/LoginServlet")
public class LoginServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();

        // Get the username from the request
        String username = request.getParameter("username");

        if (username != null && !username.isEmpty()) {
            // Create a session and store the username
            HttpSession session = request.getSession();
            session.setAttribute("username", username);

            // Redirect to the welcome page
            response.sendRedirect("WelcomeServlet");
        } else {
            out.println("<h2>Username cannot be empty. Please try again.</h2>");
        }

        out.close();
    }
}


//WelcomeServlet.java

import java.io.IOException;
import java.io.PrintWriter;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;

@WebServlet("/WelcomeServlet")
public class WelcomeServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();

        // Get the existing session (if any)
        HttpSession session = request.getSession(false);

        if (session != null) {
            // Retrieve the username from the session
            String username = (String) session.getAttribute("username");
            if (username != null) {
                out.println("<h2>Welcome, " + username + "!</h2>");
                out.println("<a href='LogoutServlet'>Logout</a>");
            } else {
                out.println("<h2>No user found in session.</h2>");
            }
        } else {
            out.println("<h2>No session found. Please login again.</h2>");
        }

        out.close();
    }
}


//LogoutServlet.java

import java.io.IOException;
import java.io.PrintWriter;
import jakarta.servlet.ServletException;
import jakarta.servlet.annotation.WebServlet;
import jakarta.servlet.http.HttpServlet;
import jakarta.servlet.http.HttpServletRequest;
import jakarta.servlet.http.HttpServletResponse;
import jakarta.servlet.http.HttpSession;

@WebServlet("/LogoutServlet")
public class LogoutServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.setContentType("text/html");
        PrintWriter out = response.getWriter();

        // Invalidate the session
        HttpSession session = request.getSession(false);
        if (session != null) {
            session.invalidate();
        }

        out.println("<h2>You have been logged out successfully!</h2>");
        out.println("<a href='login.html'>Login again</a>");
        out.close();
    }
}
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