function GetMidString(s: string; d: string; c: string): string; // 取字符串中间

var

  i, n: Integer;

begin

  try

    i := pos(d, s);

    n := pos(c, copy(s, i + 1, Length(s) - i));

    Result := copy(s, i + Length(d), n - Length(d));

  except

    Result := '';

  end;

end;

{
  "access_token": "1.a6b7dbd428f731035f771b8d********.86400.1292922000-2346678-124328",
    "expires_in": 2592000,
    "refresh_token": "2.385d55f8615fdfd9edb7c4b********.604800.1293440400-2346678-124328",
    "scope": "public audio_tts_post ...",
    "session_key": "ANXxSNjwQDugf8615Onqeik********CdlLxn",
    "session_secret": "248APxvxjCZ0VEC********aK4oZExMB",
}

str:=' "access_token": "1.a6b7dbd428f731035f771b8d********.86400.1292922000-2346678-124328",'