没有通过 servlet 中的 javascript 获得甜蜜警报

Question

（我正在使用 Intellij）我想在签入数据库后通过 servlet 的甜蜜警报向用户显示登录成功与否的消息，代码如下所示

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

           PrintWriter out=response.getWriter();
        // Connect to mysql and verify username password

        try {String un=request.getParameter("username");
            String pw=request.getParameter("password");
            Class.forName("com.mysql.jdbc.Driver");
            // loads driver
            Connection c = DriverManager.getConnection("jdbc:mysql://localhost/esofinal", "root", "admin"); // gets a new connection

            PreparedStatement ps = c.prepareStatement("select username,password,type from maincord where username=? and password=?");
            ps.setString(1, un);
            ps.setString(2, pw);

            ResultSet rs = ps.executeQuery();

            while (rs.next()) {
                HttpSession session = request.getSession();
                session.setAttribute("username", un);
                String type=rs.getString("type");
               if (type.equals("cord")) {
                   out.println("<script src='https://cdnjs.cloudflare.com/ajax/libs/limonte-sweetalert2/6.11.4/sweetalert2.all.js'></script>");
                   out.println("<script src='https://ajax.googleapis.com/ajax/libs/jquery/3.2.1/jquery.min.js'></script>");
                   out.println("<script src='https://unpkg.com/sweetalert/dist/sweetalert.min.js'></script>");
                   out.println("<script language=JavaScript>");
                   out.println("$(document).ready(function(){");
                   out.println("swal('welcome','successful!','success');");
                   out.println("});");
                   out.println("</script>");


                   RequestDispatcher rd=request.getRequestDispatcher("cord.jsp");
                   rd.include(request,response);

               }else{
                   response.sendRedirect("river.jsp");
                   return;
                }
                //request.setAttribute("username",un);
                //RequestDispatcher dispatcher = request.getRequestDispatcher("success.jsp");

                // dispatcher.forward(request,response);


            }





            response.sendRedirect("Login.jsp");
            return;
        } catch (ClassNotFoundException | SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
    }

}

数据库部分清晰。它做得很好。一旦登录成功，我想显示该警报，但这里只是在控制台中打印 Java Script 代码。（即使我尝试将这些放在 html 和 head 标签中）但它只是在控制台中打印该行。

Answer 1

工作正常，错误是我导入 System.out for out("") 而不是 Printwriter out=response.getWriter();我纠正了这一点，现在它工作正常。谢谢。