HarmonyOS 鸿蒙Next getAssets如何区分处理云端图片和本地图片

云端图片到相册，现在是一个自动的机制，手机登录华为账号，会自动拉取云端图片到相册

Q1：mediaAssetManager属于受限开放能力，需要申请受限ohos.permission.READ_IMAGEVIDEO。

咱们是否满足可申请此权限的特殊场景与功能： 应用需要克隆、备份或同步图片/视频类文件。

如果不能满足的话，只能使用Picker选择媒体库资源获取图片。

Q2：当前没有办法区分Asset是数据还是云端

主线程中open操作耗时导致，调用fs.open接口会先去下载原图。这段时间在流读文件内容，如果文件较大，不能保证在6s 内读完所有数据。主线程做这个耗时操作必然会 freeze。建议异步线程处理

// 方案1 使用文件异步接口替换同步接口
import fs, { ReadOptions, WriteOptions } from '@ohos.file.fs';
async function readFunc(uri: string, destPath: string): Promise<void> {
  let srcFile: fs.File = await fs.open(uri, fs.OpenMode.READ_ONLY);
  let destFile = fs.openSync(destPath, fs.OpenMode.WRITE_ONLY | fs.OpenMode.CREATE);
  let bufSize = 4096;
  let readSize = 0;
  let buf = new ArrayBuffer(bufSize);
  let readOptions: ReadOptions = { offset: readSize, length: bufSize };
  let readLen = await fs.read(srcFile.fd, buf, readOptions);
  while (readLen > 0) {
    readSize += readLen;
    let writeOptions: WriteOptions = { length: readLen };
    await fs.write(destFile.fd, buf, writeOptions);
    readOptions.offset = readSize;
    readLen = await fs.read(srcFile.fd, buf, readOptions);
  }
  fs.closeSync(srcFile);
  fs.closeSync(destFile);
} 

// 方案2 使用Taskpool执行IO操作
import fs, { ReadOptions, WriteOptions } from '@ohos.file.fs';
function readWriteFile(srcPath: string, destPath: string): void {
  let srcFile = fs.openSync(srcPath, fs.OpenMode.READ_ONLY | fs.OpenMode.CREATE);
  let destFile = fs.openSync(filesDir + '/destFile.txt', fs.OpenMode.WRITE_ONLY |
  fs.OpenMode.CREATE); // 读取源文件内容并写入至目的文件
  let bufSize = 4096;
  let readSize = 0;
  let buf = new ArrayBuffer(bufSize);
  let readOptions: ReadOptions = { offset: readSize, length: bufSize };
  let readLen = fs.readSync(srcFile.fd, buf, readOptions);
  while (readLen > 0) {
    readSize += readLen;
    let writeOptions: WriteOptions = { length: readLen };
    fs.writeSync(destFile.fd, buf, writeOptions);
    readOptions.offset = readSize;
    readLen = fs.readSync(srcFile.fd, buf, readOptions);
  }
  fs.closeSync(srcFile);
  fs.closeSync(destFile);
}
let filePath1: string = “path1”; // 应用文件路径
let filePath2: string = “path2”;
taskpool.execute(readWriteFile, [filePath1, filePath2]).then(() => { // 调度结果处理 })