HarmonyOS base64转image

image显示base64的图片demo如下：

const base64String = `*****************`
@Preview
@Entry
@Component
struct ImageBase64 {
  @State imagestr: string = ''
  base64Image() {
    let begin = 'data:image/jpeg;base64,'
    return begin + base64String
  }
  aboutToAppear(): void {
    this.imagestr = this.base64Image()
  }

  build() {
    Row() {
      Column() {
        Image(this.imagestr)
          .width(300)
          .height(100)
          .backgroundColor(Color.Green)
      }
      .width('100%')
    }
    .height('100%')
  }
}