如何下载网络图片到相册或者是某个指定路径，有没有demo

async func8() { 
  const transferConfig: rcp.TransferConfiguration = { 
    autoRedirect: false, 
    timeout: { 
      connectMs: 3000, 
      transferMs: 3000, 
    } 
  }; 
  const session = rcp.createSession({ requestConfiguration: { transfer: transferConfig } }); 
  let req = new rcp.Request("https://www.huawei.com/img/xxx.png", "POST"); 
  try { 
    let res = await session.fetch(req); 
    let path = getContext().filesDir + '/pic.png' 
    let file = fileIo.openSync(path, fileIo.OpenMode.READ_WRITE | fileIo.OpenMode.CREATE); 
    fileIo.write(file.fd, res.body); 
    fileIo.closeSync(file); 
    console.log(`fetch pic.png success`) 
  } catch (e) { 
    console.error(`fetch pic.png err ${JSON.stringify(e)}`) 
  } 
}