问题:java.sql.SQLException: No value specified for parameter 1

解决方案:没有指定参数

String user = req.getParameter("user");
        String pwd = req.getParameter("pwd");
        Connection conn = DbUtil.getCon();
        String sql = "select name from user where name=? and password=?";
        PreparedStatement pst = conn.prepareStatement(sql);
        pst.setString(1, user);
        pst.setString(2, pwd);