System.DirectoryServices.AccountManagement.PrincipalCollection - 如何检查主体是用户还是组？

Question

考虑以下代码：

GroupPrincipal gp = ... // gets a reference to a group

foreach (var principal in gp.Members)
 {
       // How can I determine if principle is a user or a group?         
 }

基本上我想知道的是（基于成员集合）哪些成员是用户，哪些是组。根据它们的类型，我需要触发额外的逻辑。

Answer 1

简单：

foreach (var principal in gp.Members)
{
       // How can I determine if principle is a user or a group?         
    UserPrincipal user = (principal as UserPrincipal);

    if(user != null)   // it's a user!
    {
     ......
    }
    else
    {
        GroupPrincipal group = (principal as GroupPrincipal);

        if(group != null)  // it's a group 
        {
           ....
        }
    }
}

基本上，您只需使用 as 关键字转换为您感兴趣的类型 - 如果值为 null 则转换失败 - 否则成功。

当然，另一种选择是获取类型并检查它：

foreach (var principal in gp.Members)
{
    Type type = principal.GetType();

    if(type == typeof(UserPrincipal))
    {
      ...
    }
    else if(type == typeof(GroupPrincipal))
    {
     .....
    }
}