鸿蒙 NEXT 开发中，普通对象跨线程如何传递

大家好，我是 V 哥，在鸿蒙HarmonyOS NEXT开发中，跨线程对象传递可以通过拷贝形式实现，确保两个线程的对象内容一致，但各自指向线程的隔离内存区间。以下是使用SharedArrayBuffer实现跨线程共享内存的完整案例代码，包括详细解释，整理的学习笔记，分享给大家。关注威哥不迷路，学习鸿蒙就很酷。

案例代码

1. 主线程代码

@Component
export struct LockUsage {
  taskNum: number = 10; // 任务数，实际并行线程数依设备而定
  baseDir: string = getContext().filesDir + '/TextDir'; // 文件写入的应用沙箱路径
  sabInLock: SharedArrayBuffer = new SharedArrayBuffer(4); // 在主线程，初始化子线程锁标志位，所使用的共享内存
  sabForLine: SharedArrayBuffer = new SharedArrayBuffer(4); // 在主线程，初始化子线程偏移位，所使用的共享内存
  @State result: string = "";
  build() {
    Row() {
      Column() {
        Button($r('app.string.not_use_lock'))
          .width("80%").fontSize(30)
          .fontWeight(FontWeight.Bold)
          .margin({ top: 30 })
          .onClick(async () => {
            this.startWrite(false);
          })
        Button($r('app.string.use_lock'))
          .width("80%")
          .fontSize(30)
          .fontWeight(FontWeight.Bold)
          .margin({ top: 30 })
          .onClick(async () => {
            this.startWrite(true);
          })
        Text(this.result)
          .width("80%")
          .fontSize(30)
          .fontWeight(FontWeight.Bold)
          .fontColor(Color.Blue)
          .margin({ top: 30 })
      }
      .width('100%')
    }
    .height('100%')
  }
  startWrite(useLock: boolean): void {
    this.result = getContext().resourceManager.getStringSync($r('app.string.write_file_start'));
    let whichLineToWrite: Int32Array = new Int32Array(this.sabForLine);
    Atomics.store(whichLineToWrite, 0, 0);
    let taskPoolGroup: taskpool.TaskGroup = new taskpool.TaskGroup();
    for (let i: number = 0; i < this.taskNum; i++) {
      taskPoolGroup.addTask(new taskpool.Task(createWriteTask, this.baseDir, i, this.sabInLock, this.sabForLine, useLock));
    }
    taskpool.execute(taskPoolGroup).then(() => {
      this.result = getContext().resourceManager.getStringSync($r('app.string.write_file_success'));
    }).catch(() => {
      this.result = getContext().resourceManager.getStringSync($r('app.string.write_file_failed'));
    })
  }
}

2. 子线程代码

@Concurrent
async function createWriteTask(baseDir: string, writeText: number, sabInLock: SharedArrayBuffer, sabForLine: SharedArrayBuffer, useLock: boolean): Promise<void> {
  class Option { 
    offset: number = 0;
    length: number = 0;
    encoding: string = 'utf-8';
    constructor(offset: number, length: number) {
      this.offset = offset;
      this.length = length;
    }
  }
  let filePath: string | undefined = undefined;
  filePath = baseDir + useLock ? "/useLock.txt" : "/unusedLock.txt";
  if (!fs.accessSync(baseDir)) {
    fs.mkdirSync(baseDir);
  }
  let nrl: NonReentrantLock | undefined = undefined;
  if (useLock) {
    nrl = new NonReentrantLock(sabInLock);
  }
  let whichLineToWrite: Int32Array = new Int32Array(sabForLine);
  let str: string = writeText + '\n';
  for (let i: number = 0; i < 100; i++) {
    if (useLock && nrl !== undefined) {
      nrl.lock();
    }
    let file: fs.File = fs.openSync(filePath, fs.OpenMode.READ_WRITE | fs.OpenMode.CREATE);
    try {
      fs.writeSync(file.fd, str, new Option(whichLineToWrite[0], str.length));
    } catch (err) {
      logger.error(`errorCode : ${err.code},errMessage : ${err.message}`);
    }
    fs.closeSync(file);
    whichLineToWrite[0] += str.length;
    if (useLock && nrl !== undefined) {
      nrl.unlock();
    }
  }
}

详细解释

1. 主线程初始化共享内存：
2. 子线程写入文件：
3. 线程间参数传递：
4. 线程安全写入：

这个案例展示了如何在鸿蒙HarmonyOS NEXT开发中实现跨线程对象传递和共享内存，确保线程安全和数据一致性。通过使用 SharedArrayBuffer 和线程间参数传递，可以实现高效的并发编程。关注威哥爱编程，一起向鸿蒙出发。