递归获取XML元素

看到的一道题，用递归获取XML元素....

        static void Main(string[] args)
        {
            string xmlContent = @"<FileSystem>
                                    <DriverC>
                                      <Dir DirName='MSDOS622'>
                                        <File FileName ='Command.com' ></File>
                                      </Dir>
                                      <File FileName ='MSDOS.SYS' ></File>
                                      <File FileName ='IO.SYS' ></File>
                                    </DriverC>
                                    <DriverC>
                                      <Dir>
                                        <File FileName ='DriverC.com' ></File>
                                      </Dir>
                                      <File FileName ='DriverC.SYS' ></File>
                                      <File FileName ='DriverCIO.SYS' ></File>
                                    </DriverC>
                                  </FileSystem>";

            var parentElement = XElement.Parse(xmlContent);

            var elements = FindElements(parentElement.Elements(), "File");
        }

        public static IList<XElement> FindElements(IEnumerable<XElement> elements, string elementName)
        {
            if(elements==null||elements.Count()==
                ||string.IsNullOrWhiteSpace(elementName))
            {
                return new List<XElement>();
            }

            var selectedElements = new List<XElement>();

            foreach (var element in elements)
            {
                if (element.HasElements)
                {
                    selectedElements.AddRange(FindElements(element.Elements(), elementName));
                }
                else
                {
                    if (string.Equals(element.Name.LocalName, elementName))
                    {
                        selectedElements.Add(element);
                    }
                }
            }

            return selectedElements;
        }