使用c#枚举嵌套AD用户组

我编写了一些代码来获取组和嵌套组的所有用户。我还想确保，如果组成员关系由于第一个组是最后一个组的成员而导致循环，则不会发生循环。

我写的代码工作正常，但有点慢。

这是我第一次尝试做AD查找。

有没有人可以看一下，告诉我代码看起来是好还是坏(或更糟)，或者我用错了方法?

using System;
using System.Collections.Generic;
using System.Text;
using System.DirectoryServices;
using System.IO;
namespace Tester3
{
    class Program3
    {
        public static List<string> appGroupList = new List<string>();        
        public static List<string> userList = new List<string>();
        public static List<string> groupList = new List<string>();
        public static List<string> groupChecked = new List<string>();
        static void Main(string[] args)
        {
            // Create Output File
            StreamWriter outputfile = new StreamWriter("output.txt", false);
            appGroupList.Add("GLB-SBCCitrixHelpdesk-DL");
            appGroupList.Add("SBC_UKBSAVIA001_PROD_ROL_Siebel");
            foreach (string appGroup in appGroupList)
            {
                string appGroupCN = GetCN(appGroup);
                GetMembers(appGroupCN);
                groupChecked.Clear();
            }
            foreach (string item in userList)
            {
                Console.WriteLine(item);
                outputfile.WriteLine(item);
            }
            outputfile.Flush();
            outputfile.Close();
            Console.ReadLine();
        }
        private static string GetCN(string group)
        {
            string groupCN = string.Empty;
            try
            {
                using (DirectorySearcher search = new DirectorySearcher())
                {
                    search.Filter = "(&(cn=" + group + ")(objectClass=group))";
                    search.PropertiesToLoad.Add("CN");
                    SearchResult result = search.FindOne();
                    if (result != null)
                    {
                        groupCN = result.Properties["adsPath"][0].ToString();
                        groupCN = groupCN.Replace("LDAP://", "");
                    }
                    return groupCN;
                }
            }
            catch (Exception)
            {
                return groupCN;
            }
        }
        public static void GetMembers(string group) // get members using the groups full cn 
        {
            // Check if group has already been checked
            if (groupChecked.Contains(group))
            {
                return;
            }
            // Add group to groupChecked list
            groupChecked.Add(group);
            try
            {
                // Connect to group object
                using (DirectoryEntry groupObject = new DirectoryEntry("LDAP://" + group))
                {
                    // Get member of group object
                    PropertyValueCollection col = groupObject.Properties["member"] as PropertyValueCollection;
                    // Loop through each member
                    foreach (object member in col)
                    {
                        // Connect to member object
                        using (DirectoryEntry memberObject = new DirectoryEntry("LDAP://" + member))
                        {
                            // Get class of member object
                            string memberClass = memberObject.Properties["objectClass"][1].ToString();
                            string memberCN = memberObject.Properties["Name"][0].ToString();
                            if (!groupChecked.Contains(member.ToString()))
                            {
                                if (memberClass.ToLower() == "group")
                                {                                    
                                    GetMembers(member.ToString());
                                }
                                else
                                {
                                    userList.Add(memberCN);
                                }
                            }
                            else
                            {
                                if (memberClass.ToLower() != "group")
                                {
                                    userList.Add(memberCN);
                                }
                            }
                        }
                    }
                }
            }
            catch (Exception)
            {
            }
        }
    }
}

// set up domain context
PrincipalContext ctx = new PrincipalContext(ContextType.Domain);
// find a user
UserPrincipal user = UserPrincipal.FindByIdentity(ctx, "SomeUserName");
if(user != null)
{
   // get a user's group memberships 
   foreach(Principal principal in me.GetGroups())
   {
       GroupPrincipal gp = (principal as GroupPrincipal);
       if(gp != null)
       {
           // do something with the group
       }
   }
}