private void txt_UserName_Leave(object sender, EventArgs e) { if (txt_UserName.Text != "") { if (!ub.checkUserNemeBll(txt_UserName.Text.Trim(), "checkUserNeme")) { lb_usersCheck.Text = "√"; lb_usersCheck.ForeColor = Color.Green; checkUserName = true; } else { lb_usersCheck.Text = "用户名已存在!"; lb_usersCheck.ForeColor = Color.Red; checkUserName = false; } } else { lb_usersCheck.Text = "请输入用户名"; lb_usersCheck.ForeColor = Color.Red; } }