HarmonyOS 如何从文件中读取出来cryptoFramework.DataBlob格式

参考demo：

import { buffer } from '@kit.ArkTS';
@Entry
@Component
struct Page7 {
  @State message: string = 'Hello World';
  @State content:string = ''
  build() {
    Column(){
      Button('test')
        .onClick(()=>{
          this.content = buffer.from(getContext(this).resourceManager.getRawFileContentSync("test.txt")).toString('ASCII')//转格式
          console.log("内容是："+this.content)
        })
    }
  }
}