C# 获取AD（域用户）的有关问题

DirectoryEntry entry = new DirectoryEntry(path);
DirectorySearcher searcher = new DirectorySearcher(entry);
searcher.Filter = "(objectClass=*)";

searcher.PropertiesToLoad.Clear();
SearchResultCollection searchResultCollection = searcher.FindAll();

foreach (SearchResult result in resultCollection)
            {if ([color=#FF0000]result.Properties.Contains("samaccountname"))[/color]                {
                    ResultPropertyValueCollection resultValue = result.Properties["samaccountname"];
                    if (resultValue != null && resultValue.Count > 0 && resultValue[0] != null)
                    {
                        userName = resultValue[0].ToString();
                    }
                }
}