HarmonyOS string如何转换为Unint8Array，再转换为Uint16Array？

参考代码：

import { util } from '@kit.ArkTS';
@Entry
@Component
struct StringToUint8Array {
  @State str: string = "abcdef"
  build() {
    Column({space: 5}){
      Button('StringToUint8Array')
        .onClick(() =>{
          console.info("stringToUint8Array: " + stringToUint8Array(this.str))
        })
      Button('Unint8ArrayToUint16Array')
        .onClick(() =>{
          let str = stringToUint8Array(this.str)
          console.info("Unint8ArrayToUint16Array: " + Unint8ArrayToUint16Array(str))
        })
    }
    .width('100%')
    .height('100%')
    .justifyContent(FlexAlign.Center)
  }
}
function stringToUint8Array(str: string): Uint8Array{
  let textEncoder = new util.TextEncoder();
  let buffer = new ArrayBuffer(20);
  let result = new Uint8Array(buffer);
  result = textEncoder.encodeInto(str);
  return result
}
function Unint8ArrayToUint16Array(str: Uint8Array): Uint16Array{
  let uint16Array = new Uint16Array(str.buffer);
  return uint16Array
}

参考文档：https://developer.huawei.com/consumer/cn/doc/harmonyos-references-V5/js-apis-util-V5#encodeinto9