<a href="#"><button id="cus_login" class="info" type="button">Login</button></a>

$(document).ready(function() {
$('#cus_login').click(function() {

     var username = $('#cus_name').val();
     var pw = $('#cus_password').val();
     var method = "one";

     $.ajax({
         type: "POST",
         data: {
             method: method,
             username: username,
             pw: pw
         },
         url: 'LoginServlet',
         success: function(result) {
             if(result) {
                 window.location = 'cust_profile.html'
                 console.log(result);
             }
             else{
                 alert("Login failure, please check and
try again");
             }
         },
         error, function(result) {
             console.log(result);
             alert("Connection could not be established.
Please try again.");
         }
     });
 });
});

import util.DBUtil;

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

DBUtil datasrc = new DBUtil();
Connection conn = datasrc.getConn();

protected void doPost(HttpServletRequest request, HttpServletResponse
response) throws ServletException, IOException {

    response.setContentType("text/plain");
    System.out.println("--------------------------/nDSConn
established, doGet method called");
    String method = request.getParameter("method");
    String username = request.getParameter("username");
    String pw = request.getParameter("pw");
    boolean finalstatus = false;
    boolean finalstatus1 = false;

    if(usernameCheck(username) == true && passwordCheck(pw) ==
true) {
        switch(method) {
        case "1":
            finalstatus = custLogin(username, pw);
        case "2":
            finalstatus1 = busLogin(username, pw);
        }
    }


    if(finalstatus) {
        HttpSession session = request.getSession();
        session.setAttribute("username", username);
        response.sendRedirect("cust_profile.jsp");;
    }
    else if(finalstatus1) {
        HttpSession session = request.getSession();
        session.setAttribute("username", username);
        response.sendRedirect("bus_profile.jsp");
    }
    else {
        response.sendError(001, "Unsuccessful");
    }
}

private boolean usernameCheck(String username) {
    if(username.matches("^[0-9]*$") && username.length() == 8) {
        return true;
    }
    else return false;
}

private boolean passwordCheck(String pw) {
    if(pw.length() <= 15) {
        return true;
    }
    else return false;
}
private boolean custLogin(String un, String pw) {
    PreparedStatement cps = null;
    try {
        String custsql = ("select * from fyp where cust_id = "
+ un + " password = " + pw);
        cps = conn.prepareStatement(custsql);
        ResultSet rs = cps.executeQuery();

        while(rs.next()) {
            System.out.println("Login successful");
            return true;
        }
    }
    catch (Exception e) {
        System.out.println("Login failure: ");
    }
    return false;

}
}

public class DBUtil extends HttpServlet {

static DataSource ds=null;

static {
    try {
        System.out.println("----------------------------------------------"
                + "/n DSConn initialised - method called to estabish DS");
        Context initContext = new InitialContext();
        Context envContext = (Context) initContext.lookup("java:/comp/env");
        ds = (DataSource) envContext.lookup("jdbc/fyp");

        System.out.println(ds + " DS has been established via JDNI lookup");
       }

       catch(Exception e) {
           System.out.println("Problem establishing DS");
           e.printStackTrace();
       }
    }

public Connection getConn() {
    try {
        return ds.getConnection();
    }
    catch (SQLException e) {
        System.out.println("error");
    }
    return null;
}