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Login Servlet not responding
<html>
<body>
<form action="loginservlet" method="post">
    <h1>Please Login</h1>
    Login:    <input type="text" name="username"><br>
    Password: <input type="password" name="password"><br>
    <input type=submit value="Login">
</form>
</body>
</html>

package connectm;

import java.io.IOException;
import java.io.PrintWriter;
import java.sql.*;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpSession;


public class loginservlet extends HttpServlet {


    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub

         response.setContentType("text/html");
          PrintWriter out = response.getWriter();

        Connection conn = null;
          String url = "jdbc:mysql://localhost:3306/";
          String dbName = "test";
          String driver = "com.mysql.jdbc.Driver";
          String userName = "root";
          String password = "root";
           String username="";
           String userpass="";
           String strQuery="";
          Statement st=null;
          ResultSet rs=null;
          HttpSession session = request.getSession(true);

            try {
                Class.forName(driver).newInstance();
                conn = DriverManager.getConnection(url + dbName, userName,
                        password);
                if (request.getParameter("username") != null
                        && request.getParameter("username") != ""
                        && request.getParameter("password") != null
                        && request.getParameter("password") != "") {
                    username = request.getParameter("username").toString();
                    userpass = request.getParameter("password").toString();
                    /*strQuery = "select * from user where username='" + username
                            + "' and  password='" + userpass + "'";*/
                    //System.out.println(strQuery);
                    strQuery = "select username from user where username= ? and password= ?";
                    st = conn.createStatement();
                    PreparedStatement ps=conn.prepareStatement(strQuery);
                    ps.setString(1, username);
                    ps.setString(2, userpass);
                    rs = ps.executeQuery(strQuery);
                    int count = 0;
                    while (rs.next()) {
                        session.setAttribute("username", rs.getString(1));
                        count++;
                    }
                    if (count > 0) {
                        response.sendRedirect("welcome.jsp");
                    } else {
                        response.sendRedirect("login.jsp");
                    }
                } else {
                    response.sendRedirect("login.jsp");
                }
                out.println("Connected to the database");
                conn.close();
                out.println("Disconnected from database");
            } catch (Exception e) {
                // TODO: handle exception
            }


    }

}

} catch (Exception e) {
        // TODO: handle exception
    }

} catch (Exception e) {
        throw new ServletException("Login failed", e);
    }