HarmonyOS鸿蒙Next中如何把文件管理的文件放到沙箱里面

开发者您好，你可以通过文件选择器picker选择相应音频文件，通过fs.copyFileSync方法存入沙箱目录；可通过avplayer方式调用沙箱音频文件进行播放，可通过fs.read方法读取音频文件的二进制数据。

以下为示例demo，音频文件为MP3文件：

// Index.ets
import common from '@ohos.app.ability.common';
import { BusinessError } from '@kit.BasicServicesKit';
import { fileIo as fs, picker } from '@kit.CoreFileKit';
import media from '@ohos.multimedia.media';

async function readAudioData(sandboxPath: string) {
  try {
    const file = fs.openSync(sandboxPath, fs.OpenMode.READ_ONLY);
    const stat = await fs.stat(sandboxPath);
    const buffer = new ArrayBuffer(stat.size);
    await fs.read(file.fd, buffer); // 读取文件内容
    fs.closeSync(file);
    console.info('buffer.size = ' + buffer.byteLength); // 二进制文件大小
  } catch (err) {
    console.error(`读取失败：${JSON.stringify(err)}`);
  }
}

@Entry
@Component
struct Index {
  context: common.UIAbilityContext = this.getUIContext().getHostContext() as common.UIAbilityContext;
  filePath: string = '';
  private avPlayer?: media.AVPlayer;

  // 创建播放器并设置回调
  async initPlayer(url: string) {
    // 创建实例
    this.avPlayer = await media.createAVPlayer();

    // 注册状态监听
    this.avPlayer.on('stateChange', (state: string) => {
      switch (state) {
        case 'initialized': // 资源设置完成
          this.avPlayer!.prepare();
          break;
        case 'prepared': // 准备就绪
          this.avPlayer!.play();
          console.info('开始播放');
          break;
        case 'completed': // 播放结束
          this.avPlayer!.stop();
          this.release()
          break;
      }
    });

    this.avPlayer.url = `fd://${fs.openSync(url).fd}`; // 传入沙箱地址
    console.info('url = ' + this.avPlayer.url);
  }

  // 播放控制
  play() {
    if (this.avPlayer?.state === 'paused') {
      this.avPlayer.play();
    }
  }

  pause() {
    if (this.avPlayer?.state === 'playing') {
      this.avPlayer.pause();
    }
  }

  // 销毁资源
  release() {
    this.avPlayer?.release();
  }

  // 拉起Picker选择1个音频MP3文件并复制文件到沙箱
  docPickerSelectThenCopy2Sandbox() {
    try {
      // 1. 拉起Picker选择1个文件
      let documentSelectOptions = new picker.DocumentSelectOptions();
      documentSelectOptions.maxSelectNumber = 1; // 选择文件最大个数1
      let documentPicker = new picker.DocumentViewPicker(this.context);
      documentPicker.select(documentSelectOptions).then((documentSelectResult: Array<string>) => {
        console.info('DocumentViewPicker.select successfully, documentSelectResult uri: ' +
        JSON.stringify(documentSelectResult));
        let pickerUri = documentSelectResult[0];

        // 2. 复制文件到沙箱
        let file = fs.openSync(pickerUri, fs.OpenMode.READ_ONLY);
        let pathDir = this.context.filesDir;
        this.filePath = pathDir + '/' + file.name; // 沙箱文件路径
        console.info('filePath = ' + this.filePath);
        fs.copyFileSync(file.fd, this.filePath);
        fs.closeSync(file);
        console.info('copy success');

      }).catch((err: BusinessError) => {
        console.error(`DocumentViewPicker.select failed with err, code is: ${err.code}, message is: ${err.message}`);
      });
    } catch (error) {
      let err: BusinessError = error as BusinessError;
      console.error(`DocumentViewPicker failed with err, code is: ${err.code}, message is: ${err.message}`);
    }
  }

  build() {
    Column() {
      // 保存MP3音频文件到沙箱
      Button('保存音频文件到沙箱')
        .fontSize(30)
        .onClick(() => {
          this.docPickerSelectThenCopy2Sandbox();
        });

      // 播放沙箱MP3音频文件
      Button('播放音频').onClick(() => {
        this.initPlayer(this.filePath); 
      });
      Button('暂停').onClick(() => this.pause());

      // 获取沙箱音频文件二进制数据
      Button('获取沙箱音频文件二进制数据')
        .fontSize(30)
        .onClick(() => {
          readAudioData(this.filePath);
        });
    }
    .height('100%')
    .width('100%');
  }
}

另外需要在module.json5中声明沙箱文件访问权限：

"requestPermissions": [
 {
        "name": "ohos.permission.FILE_ACCESS_PERSIST",
        "reason": "$string:reason",
        "usedScene": {
          "abilities": ["EntryAbility"],
          "when": "inuse"
        }
      },
]