HarmonyOS 鸿蒙Next 扫描控件得到扫描沙箱结果后，保存到相册失败

1、是有报错的failed to create asset by dialog successfully errCode is 400001系统错误。

2、不能用模拟器去使用DocumentScanner

3、扫描后返回白屏是因为你的代码只有一个DocumentScanner，主界面没有任何组件。

4、DocumentScanner返回的uri不是沙箱路径，不能直接调showAssetsCreationDialog来存放到相册，所以需要先将其copy到沙箱，然后再去调showAssetsCreationDialog即可保存到相册。

demo：

import { DocType, DocumentScanner, DocumentScannerConfig, SaveOption, FilterId, ShootingMode } from "@kit.VisionKit";
import { photoAccessHelper } from '@kit.MediaLibraryKit';
import { fileIo as fs, fileUri, ReadOptions, WriteOptions } from '@kit.CoreFileKit';
import json from '@ohos.util.json';
import { common } from '@kit.AbilityKit';
import { BusinessError } from '@kit.BasicServicesKit';

@Entry
@Component
struct Index {
  filePath: string = '';

  async syncToSysAlbum(fileType: photoAccessHelper.PhotoType, extension: string, ...filePath: string[]) {
    let context = getContext(this);
    let phAccessHelper = photoAccessHelper.getPhotoAccessHelper(context);
    try {
      const srcFileUris: string[] = []
      filePath.forEach(path => {
        srcFileUris.push(path)
      })
      const config: photoAccessHelper.PhotoCreationConfig[] = []
      config.push({
        title: 'background', // 可选
        fileNameExtension: extension,
        photoType: fileType,
        subtype: photoAccessHelper.PhotoSubtype.DEFAULT, // 可选
      })
      console.log("syncToSysAlarm fileUri:" + json.stringify(srcFileUris) + ",config:" + json.stringify(config))
      const desFileUris = await phAccessHelper.showAssetsCreationDialog(srcFileUris, config)
      console.debug(`目标图片 uri is : ${JSON.stringify(desFileUris)}`)
      if (desFileUris.length > 0) {
        for (let index = 0; index < desFileUris.length; index++) {
          this.copyFileContentTo(srcFileUris[index], desFileUris[index])
        }
      }
    } catch (err) {
      console.log("syncToSysAlarm filePath:" + filePath + ",error:" + json.stringify(err))
    }
  }

  @State docImageUris: string[] = []

  build() {
    Stack({ alignContent: Alignment.Top }) {
      List() {
        ForEach(this.docImageUris, (uri: string) => {
          ListItem() {
            Image(uri)
              .objectFit(ImageFit.Contain)
              .width(100)
              .height(100)
          }
        })
      }
      .listDirection(Axis.Vertical)
      .alignListItem(ListItemAlign.Center)
      .margin({
        top: 50
      })
      .width('80%')
      .height('80%')

      DocumentScanner({
        scannerConfig: {
          maxShotCount: 1,
          supportType: [DocType.DOC, DocType.SHEET],
          isGallerySupported: true
        },
        onResult: (code: number, saveType: SaveOption, uris: string[]) => {
          this.docImageUris = uris
        }
      })
      Column() {
         Button("save")
           .onClick(()=>{
             for (let i = 0; i < this.docImageUris.length; i++) {
               console.info("testaaa in the sand: " + this.docImageUris[i])
               this.copyFileToSandBox(this.docImageUris[i])
             }
             this.syncToSysAlbum(photoAccessHelper.PhotoType.IMAGE,'png', this.filePath)
           })
      }
    }
    .width('100%')
    .height('100%')
  }

  copyFileToSandBox(strUri: string) {
    console.log("testaaa 开发复制文件")
    let context = getContext(this) as common.UIAbilityContext;
    // 通过UIAbilityContext获取沙箱地址filesDir，以Stage模型为例
    let pathDir = context.filesDir;
    console.log("testaaa 沙箱文件目录路径:", pathDir)
    let dstPath = pathDir + "/" + Date.now().toString() + "_tmpimg.png";
    this.filePath = fileUri.getUriFromPath(dstPath)
    console.log("testaaa 沙箱文件URI" + this.filePath);
    fs.copy(strUri, this.filePath, (err: BusinessError) => {
      if (err) {
        console.error(`testaaa Failed to copy: ${JSON.stringify(err)}`);
        return;
      }
      console.info("testaaa Succeeded in copying. ");
    })
  }

  /**
   * 复制文件内容到目标文件
   * @param srcFilePath 源文件路径
   * @param destFilePath 目标文件路径
   */
  copyFileContentTo(srcFilePath: string, destFilePath: string) {
    let srcFile = fs.openSync(srcFilePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE)
    let destFile = fs.openSync(destFilePath, fs.OpenMode.READ_WRITE | 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);
    }
    // 关闭文件
    fs.closeSync(srcFile);
    fs.closeSync(destFile);
  }
}