HarmonyOS 鸿蒙Next digest的编码格式错误

HarmonyOS 鸿蒙Next digest的编码格式错误 使用安全类库@ohos.security.cryptoFramework的digest接口，实现字符串的sha256摘要算法，实现代码如下

import cryptoFramework from "[@ohos](/user/ohos).security.cryptoFramework"
import util from "[@ohos](/user/ohos).util"

export namespace Digest {
  export async function sha256(str: string): Promise<string> {
    return digest(str, 'SHA256')
  }

  export async function digest(str: string, algName: string): Promise<string> {
    let bytes = string2bytes(str)
    let md = cryptoFramework.createMd(algName)
    await md.update({
      data: bytes
    })
    let result = await md.digest()
    let hash1 = bytes2string(result.data)
    let hash2 = bytes2string2(result.data)

    console.log(`zx_debug hash1 = ${hash1}`)
    console.log(`zx_debug hash2 = ${hash2}`)

    return hash1
  }

  function string2bytes(str: string): Uint8Array {
    let encoder = new util.TextEncoder()
    let buffer = new ArrayBuffer(str.length)
    let dest = new Uint8Array(buffer)
    encoder.encodeIntoUint8Array(str, dest)
    return dest
  }

  function bytes2string2(arr: Uint8Array): string {
    let textDecoder = util.TextDecoder.create();
    return textDecoder.decodeWithStream(arr);
  }

  function bytes2string(bytes: Uint8Array): string {
    for (var hex = [], i = 0; i < bytes.length; i++) {
      hex.push((bytes[i] >>> 4).toString(16));
      hex.push((bytes[i] & 0xF).toString(16));
    }
    return hex.join("");
  }

}

Digest.sha256('hello')

digest返回的Uint8Array，转换为字符串，有两个实现，其中：

• bytes2string 可以正确返回sha256摘要字符串；
• bytes2string2 不可以。

digest的入参是使用TextEncoder编码的格式，为什么返回值不能用TextDecoder解码？