HarmonyOS 获取相册图片大小以及视频时长

可以参考如下demo：

import photoAccessHelper from '@ohos.file.photoAccessHelper';
import { BusinessError } from '@ohos.base';
import dataSharePredicates from '@ohos.data.dataSharePredicates';
import { picker } from '@kit.CoreFileKit';

@Entry
@Component
struct Index {
  // 定义一个uri数组，用于接收PhotoViewPicker选择图片返回的uri
  @State uris: Array<string> = [];
  context = getContext(this);

  // 调用PhotoViewPicker.select选择图片
  async photoPickerGetUri() {
    try {
      let photoViewPicker = new picker.PhotoViewPicker();
      photoViewPicker.select().then(async (PhotoSelectResult: picker.PhotoSelectResult) => {
        console.info('PhotoViewPicker.select successfully, PhotoSelectResult uri: ' +
        JSON.stringify(PhotoSelectResult));
        this.uris = PhotoSelectResult.photoUris;
        this.uriGetAssets()
      }).catch((err: BusinessError) => {
        console.error('PhotoViewPicker.select failed with err: ' + JSON.stringify(err));
      });
    } catch (error) {
      let err: BusinessError = error as BusinessError;
      console.error('PhotoViewPicker failed with err: ' + JSON.stringify(err));
    }
  }

  async uriGetAssets() {
    try {
      let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(this.context);
      let predicates: dataSharePredicates.DataSharePredicates = new dataSharePredicates.DataSharePredicates();
      // 配置查询条件，使用PhotoViewPicker选择图片返回的uri进行查询
      predicates.equalTo('uri', this.uris[0]);
      let fetchOption: photoAccessHelper.FetchOptions = {
        fetchColumns: [photoAccessHelper.PhotoKeys.WIDTH, photoAccessHelper.PhotoKeys.HEIGHT,
          photoAccessHelper.PhotoKeys.TITLE, photoAccessHelper.PhotoKeys.SIZE, photoAccessHelper.PhotoKeys.DURATION],
        predicates: predicates
      };
      let fetchResult: photoAccessHelper.FetchResult<photoAccessHelper.PhotoAsset> =
        await phAccessHelper.getAssets(fetchOption);
      // 得到uri对应的PhotoAsset对象，读取文件的部分信息
      const asset: photoAccessHelper.PhotoAsset = await fetchResult.getFirstObject();
      console.info('asset displayName: ', asset.displayName);
      console.info('asset uri: ', asset.uri);
      console.info('asset photoType: ', asset.photoType);
      console.info('asset width: ', asset.get(photoAccessHelper.PhotoKeys.WIDTH));
      console.info('asset height: ', asset.get(photoAccessHelper.PhotoKeys.HEIGHT));
      console.info('asset SIZE: ' + asset.get(photoAccessHelper.PhotoKeys.SIZE));
      console.info('asset DURATION: ' + asset.get(photoAccessHelper.PhotoKeys.DURATION));
      // 获取缩略图
      asset.getThumbnail((err, pixelMap) => {
        if (err == undefined) {
          console.info('getThumbnail successful ' + JSON.stringify(pixelMap));
        } else {
          console.error('getThumbnail fail', err);
        }
      });
    } catch (error) {
      console.error('uriGetAssets failed with err: ' + JSON.stringify(error));
    }
  }

  build() {
    Button('获取文件大小').width(100).height(100)
      .onClick(() => {
        this.photoPickerGetUri()
      })
  }
}