C# 判断文件编码

public static Encoding GetFileEncodingByContent(string path)
        {
            var contentWithUTF8 = File.ReadAllText(path, Encoding.UTF8);
            var contentWithGBK = File.ReadAllText(path, Encoding.GetEncoding("GBK"));
            if (contentWithUTF8.Length < contentWithGBK.Length)
                return Encoding.UTF8;
            else if (contentWithUTF8.Length == contentWithGBK.Length)
            {
                using (var reader = new StreamReader(path, true))
                {
                    reader.Peek(); // you need this!
                    return reader.CurrentEncoding;
                }
            }
            else
                return Encoding.GetEncoding("GBK");
            
        }