HarmonyOS arraybuffer转base64乱码

import { util } from '@kit.ArkTS'; 
 
function base64(){ 
  let base64 = new util.Base64Helper 
  let arr = new Uint8Array([48, 49, 2, 1, 1, 4, 32, 115, 56]); 
  let a = base64.encodeToStringSync(arr) 
  console.log(a) 
}