【HarmonyOSNext】應用文件訪問

import { common } from '@kit.AbilityKit';
import { fileIo, ReadOptions } from '@kit.CoreFileKit';
import { buffer } from '@kit.ArkTS';

@Entry
@Component
struct File_Page {
  @State message: string = 'Hello World';

  /**
   * 創建文件并寫入內容
   */
  CreateFile(): void {
    let context = getContext(this) as common.UIAbilityContext;
    let filesDir = context.filesDir;
    //文件路徑
    let filePath: string = filesDir + "/MyTest.txt";
    //新建并打開一個文件
    let file = fileIo.openSync(filePath, fileIo.OpenMode.CREATE | fileIo.OpenMode.READ_WRITE);
    //寫入內容
    let writeLen = fileIo.writeSync(file.fd, "我是寫入測試2");
    fileIo.closeSync(file);
  }

  /**
   * 讀取創建的文件
   */
  async ReadFile(): Promise<void> {
    let context = getContext(this) as common.UIAbilityContext;
    let filesDir = context.filesDir;
    //文件路徑
    let filePath: string = filesDir + "/MyTest.txt";
    if (await fileIo.access(filePath) == false) {
      console.info("文件不存在");
      return;
    }
    //打開一個文件
    let file = fileIo.openSync(filePath, fileIo.OpenMode.READ_WRITE);
    // 從文件讀取一段內容
    let arrayBuffer = new ArrayBuffer(2048);
    let readOptions: ReadOptions = {
      offset: 0,
      length: arrayBuffer.byteLength
    };
    let readLen = fileIo.readSync(file.fd, arrayBuffer, readOptions);
    let buf = buffer.from(arrayBuffer, 0, readLen);
    console.info(buf.toString());
    fileIo.closeSync(file);
  }

  build() {
    Column() {
      Button("點擊創建文件")
        .width("80%")
        .onClick(() => this.CreateFile())
      Button("點擊讀取文件內容")
        .width("80%")
        .margin({ top: 20 })
        .onClick(() => this.ReadFile())
    }
    .height('100%')
    .width('100%')
  }
}
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