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鸿蒙NEXT实战：使用公共事件实现跨进程通信

news 2025/10/10 11:38:28

在鸿蒙应用开发中，巧妙使用公共事件机制，能让跨进程通信变得轻松高效。

在鸿蒙应用开发中，进程间通信（IPC）是一个常见需求。HarmonyOS NEXT 提供了多种IPC机制，其中公共事件（Common Event）因其简单易用且支持一对多通信模式，成为许多场景下的理想选择。

公共事件机制概述

公共事件是HarmonyOS中的一种发布-订阅模式的通信机制，适用于跨进程、跨应用的事件通知场景。它基于消息中心机制，允许一个进程发布事件，多个进程订阅并接收该事件。

公共事件的特点：

跨进程通信：能够在不同进程间传递事件
一对多通信：一个事件可以被多个订阅者接收
异步执行：事件发布后立即返回，不会阻塞发布者线程
松耦合：发布者和订阅者不需要知道彼此的存在

公共事件的工作原理

公共事件机制涉及三个核心角色：

发布者：负责创建并发布公共事件
订阅者：注册对特定事件的兴趣，并定义回调处理函数
公共事件管理器：系统组件，负责管理事件的分发

当发布者发布一个事件时，公共事件管理器会根据事件的类型和权限，将事件传递给所有匹配的订阅者。

实战：使用公共事件实现跨进程通信

下面通过一个完整示例，演示如何在鸿蒙NEXT中使用公共事件进行跨进程通信。

1. 创建事件订阅者

首先，我们需要在接收方进程中创建事件订阅者：

typescript

import commonEventManager from '@ohos.commonEventManager';
import Base from '@ohos.base';// 订阅公共事件
function subscribeCommonEvent() {const subscribeInfo = {events: ["com.example.demo.MY_EVENT"]  // 要订阅的事件类型};// 创建订阅者commonEventManager.createSubscriber(subscribeInfo, (err: Base.BusinessError, subscriber: commonEventManager.CommonEventSubscriber) => {if (err) {console.error(`Failed to create subscriber. Code is ${err.code}, message is ${err.message}`);return;}console.info('Succeeded in creating subscriber.');// 订阅事件if (subscriber !== null) {commonEventManager.subscribe(subscriber, (err: Base.BusinessError, data: commonEventManager.CommonEventData) => {if (err) {console.error(`Failed to subscribe common event. Code is ${err.code}, message is ${err.message}`);return;}console.info('Subscribe success, received event data:' + JSON.stringify(data));// 处理接收到的事件数据handleReceivedEvent(data);});} else {console.error(`Need create subscriber`);}});
}// 处理接收到的事件
function handleReceivedEvent(eventData: commonEventManager.CommonEventData) {const receivedData = eventData.data;const code = eventData.code;console.info(`Received event, code: ${code}, data: ${JSON.stringify(receivedData)}`);// 根据事件数据更新UI或执行其他操作// ...
}

2. 发布公共事件

在发送方进程中，创建并发布公共事件：

typescript

import commonEventManager from '@ohos.commonEventManager';
import Base from '@ohos.base';// 发布公共事件
function publishCommonEvent() {const options: commonEventManager.CommonEventPublishData = {code: 1,  // 事件代码data: "This is event data",  // 事件数据bundleName: "com.example.publisher"  // 可选：发布者包名};// 发布公共事件commonEventManager.publish("com.example.demo.MY_EVENT", options, (err: Base.BusinessError) => {if (err) {console.error('[CommonEvent] PublishCallBack err=' + JSON.stringify(err));} else {console.info('[CommonEvent] Publish success');}});
}// 发布带复杂数据的事件
function publishComplexEvent() {const complexData = {message: "Hello from another process!",timestamp: new Date().getTime(),count: 42};const options: commonEventManager.CommonEventPublishData = {code: 1001,data: JSON.stringify(complexData)  // 复杂数据需要序列化};commonEventManager.publish("com.example.demo.COMPLEX_EVENT", options, (err: Base.BusinessError) => {if (err) {console.error('Failed to publish complex event: ' + JSON.stringify(err));} else {console.info('Complex event published successfully');}});
}

3. 在Ability中集成公共事件

在EntryAbility中订阅公共事件：

typescript

import UIAbility from '@ohos.app.ability.UIAbility';
import commonEventManager from '@ohos.commonEventManager';
import window from '@ohos.window';
import Base from '@ohos.base';export default class EntryAbility extends UIAbility {private subscriber: commonEventManager.CommonEventSubscriber | null = null;onCreate(want: Want, launchParam: AbilityConstant.LaunchParam): void {console.info('EntryAbility onCreate');this.subscribeToEvents();}private subscribeToEvents(): void {const subscribeInfo = {events: ["com.example.demo.MY_EVENT"]};commonEventManager.createSubscriber(subscribeInfo, (err: Base.BusinessError, subscriber: commonEventManager.CommonEventSubscriber) => {if (err) {console.error(`Failed to create subscriber in Ability. Code is ${err.code}, message is ${err.message}`);return;}this.subscriber = subscriber;console.info('Succeeded in creating subscriber in Ability.');if (this.subscriber !== null) {commonEventManager.subscribe(this.subscriber, (err: Base.BusinessError, data: commonEventManager.CommonEventData) => {if (err) {console.error(`Failed to subscribe common event in Ability. Code is ${err.code}, message is ${err.message}`);return;}console.info('Ability received event data: ' + JSON.stringify(data));});}});}onDestroy(): void {// 取消订阅if (this.subscriber !== null) {commonEventManager.unsubscribe(this.subscriber, (err: Base.BusinessError) => {if (err) {console.error(`Failed to unsubscribe common event. Code is ${err.code}, message is ${err.message}`);return;}console.info('Succeeded in unsubscribing common event.');});}super.onDestroy();}
}

4. 在UI页面中发布事件

在SubPage.ets页面中发布事件：

typescript

@Entry
@Component
struct SubPage {@State message: string = 'Hello World';build() {Column() {Text(this.message).fontSize(20).margin(10)Button('发布简单事件').onClick(() => {this.publishSimpleEvent();}).margin(10)Button('发布复杂事件').onClick(() => {this.publishComplexEvent();}).margin(10)}.width('100%').height('100%')}private publishSimpleEvent() {let options: commonEventManager.CommonEventPublishData = {code: 1,data: "initial data",};commonEventManager.publish("selfPublishEvent", options, (err: Base.BusinessError) => {if (err) {console.error('[CommonEvent] PublishCallBack err=' + JSON.stringify(err));} else {console.info('[CommonEvent] Publish success');this.message = '事件发布成功！';}});}private publishComplexEvent() {const eventData = {action: 'USER_ACTION',userId: '12345',screen: 'MainPage',timestamp: new Date().toISOString()};let options: commonEventManager.CommonEventPublishData = {code: 200,data: JSON.stringify(eventData),};commonEventManager.publish("com.example.demo.USER_ACTION_EVENT", options, (err: Base.BusinessError) => {if (err) {console.error('Failed to publish user action event: ' + JSON.stringify(err));this.message = '事件发布失败';} else {console.info('User action event published successfully');this.message = '用户动作事件已发布';}});}
}

公共事件的进阶用法

1. 使用有序公共事件

有序公共事件允许订阅者按照优先级处理事件，并可以终止事件的传播：

typescript

// 发布有序公共事件
function publishOrderedEvent() {const options: commonEventManager.CommonEventPublishData = {code: 1,data: "Ordered event data",isOrdered: true  // 设置为有序事件};commonEventManager.publish("com.example.demo.ORDERED_EVENT", options, (err: Base.BusinessError) => {if (err) {console.error('Failed to publish ordered event: ' + JSON.stringify(err));} else {console.info('Ordered event published successfully');}});
}

2. 使用粘性公共事件

粘性事件会在发布后保留在系统中，新的订阅者仍然可以收到之前发布的事件：

typescript

// 发布粘性公共事件
function publishStickyEvent() {const options: commonEventManager.CommonEventPublishData = {code: 1,data: "Sticky event data",isSticky: true  // 设置为粘性事件};commonEventManager.publish("com.example.demo.STICKY_EVENT", options, (err: Base.BusinessError) => {if (err) {console.error('Failed to publish sticky event: ' + JSON.stringify(err));} else {console.info('Sticky event published successfully');}});
}

3. 订阅系统公共事件

除了自定义事件，还可以订阅系统预定义的公共事件：

typescript

// 订阅系统事件：屏幕点亮
function subscribeSystemEvent() {const subscribeInfo = {events: [commonEvent.SCREEN_ON]  // 系统预定义事件};commonEventManager.createSubscriber(subscribeInfo, (err: Base.BusinessError, subscriber: commonEventManager.CommonEventSubscriber) => {if (err) {console.error(`Failed to create system event subscriber. Code is ${err.code}, message is ${err.message}`);return;}if (subscriber !== null) {commonEventManager.subscribe(subscriber, (err: Base.BusinessError, data: commonEventManager.CommonEventData) => {if (err) {console.error(`Failed to subscribe system event. Code is ${err.code}, message is ${err.message}`);return;}console.info('Screen turned on');// 处理屏幕点亮事件});}});
}