Dictionary——通过value找Key
Dictionary<string, string> dic = GetRoleDescriptions();
string key = dic.FirstOrDefault(x => x.Value == ddlSearchRoleDes.SelectedItem.Text.Trim().ToUpper()).Key;
Dictionary<string, string> dic = GetRoleDescriptions();
string key = dic.FirstOrDefault(x => x.Value == ddlSearchRoleDes.SelectedItem.Text.Trim().ToUpper()).Key;