Promise和async/await提供異步并發能力，適用于單次I/O任務的場景開發，本文以使用異步進行單次文件寫入為例來提供指導。

實現單次I/O任務邏輯。

import fs from '@ohos.file.fs';
import common from '@ohos.app.ability.common';

async function write(data: string, file: fs.File): Promise< void > {
  fs.write(file.fd, data).then((writeLen: number) = > {
    console.info('write data length is: ' + writeLen)
  }).catch((err) = > {
    console.error(`Failed to write data. Code is ${err.code}, message is ${err.message}`);
  })
}

采用異步能力調用單次I/O任務。

async function testFunc(): Promise< void > {
  let context = getContext() as common.UIAbilityContext;
  let filePath: string = context.filesDir + "/test.txt"; // 應用文件路徑
  let file: fs.File = await fs.open(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
  write('Hello World!', file).then(() = > {
    console.info('Succeeded in writing data.');
  }).catch((err) = > {
    console.error(`Failed to write data. Code is ${err.code}, message is ${err.message}`);
  })
  fs.close(file);
}
testFunc();

審核編輯 黃宇