Delete Dictionary circulating collection is empty Key, other collections can transform

/// <summary>
/// 移除为空的Key
/// </summary>
/// <param name="dic"></param>
/// <returns></returns>
private static Dictionary<string, string> RemoveNullKey(Dictionary<string, string> dic)
{
string keyNames = "";
foreach (string key in dic.Keys)
{
if(string.IsNullOrEmpty(dic[key]))
{
keyNames += key + ",";
}
}
string[] str_keyNames = keyNames.Split(new char[] { ',' }, StringSplitOptions.RemoveEmptyEntries);

foreach (string key in str_keyNames)
{
dic.Remove(key);
}
return dic;
}