函数：base64_encode BASE64 编码

函数名称：BASE64 编码

函数功能：字符串 BASE64 编码（模式为 ECB）

函数用例

local ts = require("ts")
local msg = "我是重要信息"
local key = "我是秘钥"
local emsg = msg:aes128_encrypt(key)
local emsgb64 = emsg:base64_encode()
dialog(emsgb64)

-- 文件 BASE64 编码
local ts = require("ts")
path = userPath().."/res/test.png"
snapshot(path,0,0,200,200)
function _ReadFileBase64(path)
    f = io.open(path,"rb")
    if f == null then
        return null;
    end 
    bytes = f:read("*all");
    f:close();
    return bytes:base64_encode();
end
str  = _ReadFileBase64(path)