如何以编程方式获取有权访问SharePoint中的文件或文件夹的用户和组的列表

我正在尝试找到一种方法，以获取有权访问继承中断的文件夹或文件的AD用户和AD组的列表。我不需要知道如何找到继承断开的部分，我已经了解了这一部分，但是在查找每个具有访问权限的用户或组时遇到了问题。我不想看到AD组中有哪些用户，只想看到正在访问文件夹的组的名称。这背后的用例是我们不希望将安全文件夹共享给单个用户。所有这些都只能由AD组控制（网站所有者无权将用户添加到安全文件夹）。还需要找出该文件夹中是否有任何文件不继承自该文件夹，并且也共享给各个用户而不是AD组（希望这是有道理的）。这是我到目前为止的内容，并且在一定程度上可以奏效，

到目前为止，这是我已经编写的代码。它接受文件或文件夹的item对象以及对字符串的引用。它扫描访问，然后构建用分号分隔的用户列表，如果spuser对象之一是用户而不是组，则返回true：

/// <summary>
    /// Provides list of users\groups that have access to a List Item.
    /// </summary>
    /// <param name="spListItem">Item to check access of</param>
    /// <returns>semi colon delimited list of users\groups with access in a referenced list and boolean value indicating if a direct user exists</returns>
    public bool GetListItemUserAccess(SPListItem spListItem, ref string accountsWithAccess)
    {
        //string accountsWithAccess = string.Empty;
        bool IsFirstIteration = true;
        bool domainUserExits = false;
        SPRoleAssignmentCollection spItemRoles = spListItem.RoleAssignments;    
        SPRoleDefinitionCollection rolesInWeb = spListItem.Web.RoleDefinitions;

        foreach(SPRoleAssignment spRole in spItemRoles)
        {

            SPPrincipal spPrincipal = spRole.Member;

            //cast as SPGroup or SPUser to determine if is a SPGroup or User
            if((spPrincipal as SPGroup) != null)
            {
                SPGroup spGroup = spPrincipal as SPGroup;
                SPUserCollection usersInGroup = spGroup.Users;

                //report on each user in group
                foreach(SPUser spUser in usersInGroup)
                {
                    //check to see if it is a user group
                    if(!spUser.IsDomainGroup)
                    {
                        domainUserExits = true;
                    }

                    //add to list for report.
                    if(IsFirstIteration)
                    {
                        IsFirstIteration = false;                            
                    }
                    else
                    {
                        accountsWithAccess += ";";                            
                    }

                    //depending on the account type sometimes the Login name has the credentials and sometimes it has 
                    //a UID
                    if (spUser.LoginName.ToLower().Contains("<company name>"))
                    {
                        accountsWithAccess += this.ParseUserIDFromClaim(spUser.LoginName);
                    }
                    else
                    {
                        accountsWithAccess += this.ParseUserIDFromClaim(spUser.Name);
                    }
                }
            }
            else if((spPrincipal as SPUser) != null)
            {
                //check to see if the user has limited access only (we don't report on this as this occurs when user has access to something in site)
                  if(!spListItem.DoesUserHavePermissions(spPrincipal as SPUser, SPBasePermissions.ViewListItems))
                {
                    continue;
                }

                //check to see if it is a user group
                if (!(spPrincipal as SPUser).IsDomainGroup)
                {
                    domainUserExits = true;
                }

                //add to list for report.
                if(IsFirstIteration)
                {
                    IsFirstIteration = false;
                }
                else
                {
                    accountsWithAccess += ";";
                }

                //depending on the account type sometimes the Login name has the credentials and sometimes it has 
                //a UID
                if (spPrincipal.LoginName.ToLower().Contains("<company name>"))
                {
                    accountsWithAccess += this.ParseUserIDFromClaim(spPrincipal.LoginName);
                }
                else
                {
                    accountsWithAccess += this.ParseUserIDFromClaim(spPrincipal.Name);
                }
            }
        }
        return domainUserExits;
    }