base64與檔案互轉

/// <summary>
        /// 檔案轉換成Base64字串
        /// </summary>
        /// <param name="fileName">檔案絕對路徑</param>
        /// <returns></returns>
        public static String FileToBase64(string fileName)
        {
            string strRet ="";

            try
            {
                FileStream fs = new FileStream(fileName, FileMode.Open);
                byte[] bt = new byte[fs.Length];
                fs.Read(bt, 0, bt.Length);
                strRet = Convert.ToBase64String(bt);
                fs.Close();
            }
            catch (Exception ex)
            {
                strRet = null;
            }

            return strRet;
        }

        /// <summary>
        /// Base64字串轉換成檔案
        /// </summary>
        /// <param name="strInput">base64字串</param>
        /// <param name="fileName">儲存檔案的絕對路徑</param>
        /// <returns></returns>
        public static bool Base64ToFileAndSave(string strInput, string fileName)
        {
            bool bTrue = false;
            try
            {
                byte[] buffer = Convert.FromBase64String(strInput);
                FileStream fs = new FileStream(fileName, FileMode.OpenOrCreate);
                fs.Write(buffer, 0, buffer.Length);
                fs.Close();
                bTrue = true;
            }
            catch (Exception ex)
            {
                
            }
            return bTrue;
        }
 

byte[]與檔案互轉

/// <summary>
        /// 建立檔案路徑
        /// </summary>
        /// <param name="filepath"></param>
        /// <returns></returns>
        public static void CreatePath(string filepath)
        {
            if (!Directory.Exists(filepath))
            {
                var securityRules = new DirectorySecurity();
                securityRules.AddAccessRule(new FileSystemAccessRule(Environment.UserName, FileSystemRights.FullControl, AccessControlType.Allow));
                securityRules.AddAccessRule(new FileSystemAccessRule("Everyone", FileSystemRights.FullControl, AccessControlType.Allow));
                securityRules.AddAccessRule(new FileSystemAccessRule("NETWORK SERVICE", FileSystemRights.FullControl, AccessControlType.Allow));
                Directory.CreateDirectory(filepath, securityRules);
            }
        }

        /// <summary>
        /// 檔案轉byte[]
        /// </summary>
        /// <param name="fileName"></param>
        /// <returns></returns>
        public static byte[] ReadFileToByte(string fileName)
        {
            FileStream pFileStream = null;
            byte[] pReadByte = new byte[0];
            try
            {
                pFileStream = new FileStream(fileName, FileMode.Open, FileAccess.Read);
                BinaryReader r = new BinaryReader(pFileStream);
                r.BaseStream.Seek(0, SeekOrigin.Begin);    //將檔案指標設定到檔案開
                pReadByte = r.ReadBytes((int)r.BaseStream.Length);
                return pReadByte;
            }
            catch
            {
                return pReadByte;
            }
            finally
            {
                if (pFileStream != null)
                {
                    pFileStream.Close();
                }                   
            }
        }
        /// <summary>
        /// 儲存檔案
        /// </summary>
        /// <param name="file"></param>
        /// <param name="fileName"></param>
        /// <returns></returns>
        public static bool SaveFile(byte[] file,string fileName)
        {
            bool isSave = false;
            try
            {
                using (var ms = new MemoryStream())
                {
                    MemoryStream m = new MemoryStream(file);
                    FileStream fs = new FileStream(fileName, FileMode.OpenOrCreate);
                    m.WriteTo(fs);
                    m.Close();
                    fs.Close();
                }
                isSave = true;
            }
            catch(Exception ex)
            {

            }
            return isSave;
        }