typhon自带base64函数

使用 unit base64;  

编码函数

function EncodeStringBase64(const s:string):String;

解码函数

function DecodeStringBase64(const s:string;strict:boolean=false):String; 

解释：

(* The TBase64DecodingStream supports two modes:
   * - 'strict mode':
   *    - follows RFC3548
   *    - rejects any characters outside of base64 alphabet,
   *    - only accepts up to two '=' characters at the end and
   *    - requires the input to have a Size being a multiple of 4; otherwise raises an EBase64DecodingException
   * - 'MIME mode':
   *    - follows RFC2045
   *    - ignores any characters outside of base64 alphabet
   *    - takes any '=' as end of string
   *    - handles apparently truncated input streams gracefully
   *)
  TBase64DecodingMode = (bdmStrict, bdmMIME);