HarmonyOS 鸿蒙Next：taskpool结合emitter，实现主线程和多个子线程之间的通信

在这个示例中，我们创建了两个子线程，分别实现了每隔200毫秒计数器加一，并向主线程发送一条数据，同时更新主界面的UI

通过taskpool创建并发任务

通过emitter实现在主线程中向子线程发送消息

在子线程中通过信号变量控制任务的执行

完整代码如下：

Index.ets

import emitter, { sleep, event1, event2 } from ‘…/common/Event’
import { taskpool } from ‘@kit.ArkTS’;
import router from ‘@ohos.router’;

@Entry
@Component
struct Index {
@State count1: number = 0;
@State count2: number = 0;
build() {
Row() {
Column({ space: 20 }) {
Text(任务<span class="hljs-number">1</span>: ${<span class="hljs-keyword">this</span>.count1}).fontSize(30)
Text(任务<span class="hljs-number">2</span>: ${<span class="hljs-keyword">this</span>.count2}).fontSize(30)
    Button(<span class="hljs-string">"开始所有任务"</span>).onClick(() =&gt; {
      run(event1, (count: number) =&gt; <span class="hljs-keyword">this</span>.count1 = count)
      run(event2, (count: number) =&gt; <span class="hljs-keyword">this</span>.count2 = count)
    })
    <span class="hljs-comment">// 向子线程1发送事件</span>
    Button(<span class="hljs-string">"停止任务1"</span>).onClick(() =&gt; emitter.emit(event1));
    <span class="hljs-comment">// 向子线程2发送事件</span>
    Button(<span class="hljs-string">"停止任务2"</span>).onClick(() =&gt; emitter.emit(event2))

  
  }.width(<span class="hljs-string">'100%'</span>)
}.height(<span class="hljs-string">'80%'</span>)
}
}
// 启动任务
function run(event: emitter.InnerEvent, callback: Function) {
let task: taskpool.Task = new taskpool.Task(taskFunc, event);
// 分发任务
taskpool.execute(task);
// 接收子线程的数据
task.onReceiveData(callback);
}
@Concurrent
async function taskFunc(event: emitter.InnerEvent) {
// 声明信号变量来控制任务的执行，注意，这个信号变量必须声明在@Concurrent函数内部
let signal: boolean = false;
// 订阅事件，通过emitter控制信号
emitter.on(event, () => signal = true);
for (let i = 0; i < 100; i++) {
// 信号为真时停止任务
if (signal) return;
// 向主线程发送消息
taskpool.Task.sendData(i);
// 睡200ms
await sleep(200)
}
}
<button style="position: absolute; padding: 4px 8px 0px; cursor: pointer; top: 8px; right: 8px; font-size: 14px;">复制</button>

common/Event.ets

import emitter from ‘@ohos.events.emitter’;
const event1: emitter.InnerEvent = {
eventId: 1,
priority: emitter.EventPriority.HIGH
}
const event2: emitter.InnerEvent = {
eventId: 2,
priority: emitter.EventPriority.HIGH
}
const sleep: (ms: number) => Promise<void> = (ms) => new Promise(resolve => setTimeout(resolve, ms));

export { sleep, event1, event2 };
export default emitter;<button style="position: absolute; padding: 4px 8px 0px; cursor: pointer; top: 8px; right: 8px; font-size: 14px;">复制</button>