HarmonyOS 中文base64加密解密乱码

let textEncoder = new util.TextEncoder("utf-8"); 
let input='{"act":"GetPurchased","uid":"10074013","page":1,"tag":1,"flg":1,"title":"刘"}'; 
let shuzu= textEncoder.encodeInto(input) 
// 解密前 
let that = new util.Base64Helper(); 
let result = that.encodeToStringSync(shuzu); 
let waitDecodeArr = that.decodeSync(result) 
 
let textDecoder = util.TextDecoder.create('utf-8') 
let decodeResult = textDecoder.decodeWithStream(waitDecodeArr)