/// <summary>
        /// 登录按钮点击事件
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void btnLogin_Click(object sender, EventArgs e)
        {
            _accountDao = new AccountDao();
            // 如果用户已经存在
            if (!_accountDao.IsAccountExist(TextUsername.Text.Trim()))
            {
                ErrorInfo.Text = "您所输入的用户不存在!";
                return;
            }
            // 验证登录
            Account account = new Account();

            account.Username = TextUsername.Text.Trim();
            account.Password = TextPassword.Text.Trim();
            account          = _accountDao.AccountLogin(account);
            // 登录失败
            if (account == null)
            {
                ErrorInfo.Text = "您输入的密码不正确!";
            }
            // 登录成功
            else
            {
                if (CheckBoxRemind.Checked)
                {
                    HttpCookie cookie = new HttpCookie("accountId");
                    cookie.Expires = DateTime.Now.AddDays(7);
                    cookie.Value   = account.Id + "";
                    Response.Cookies.Add(cookie);
                }

                Session["account"] = account;
                ErrorInfo.Style.Add("color", "green");
                ErrorInfo.Text = "登录成功,3秒后自动跳转...";
                Response.Write("<meta   http-equiv='refresh'   content='3;URL=./Main.aspx'>");
            }
        }