目录

如何发布本地消息到通知中心

问题现象

  1. HarmonyOS有没有类似其他平台的通知中心（NSNotificationCenter）的能力？
  2. 如何实现应用本地发送一条消息到通知中心？

效果预览

背景知识

Notification Kit（用户通知服务）为开发者提供本地通知发布通道，开发者可借助Notification Kit将应用产生的通知直接在客户端本地推送给用户，本地通知根据通知类型及发布场景会产生对应的铃声、震动、横幅、锁屏、息屏、通知栏提醒和显示。

解决方案

  1. HarmonyOS提供了Notification Kit，为开发者提供本地通知发布通道。
  2. 本地发送消息到通知中心可以参考如下示例代码：
    import { notificationManager } from '@kit.NotificationKit';
import { BusinessError } from '@kit.BasicServicesKit';
import { common } from '@kit.AbilityKit';
import { PromptAction } from '@kit.ArkUI';

const TAG: string = '[PublishOperation]';
const DOMAIN_NUMBER: number = 0xFF00;

@Entry
@Component
struct NotificationPage {
  uiContext: UIContext = this.getUIContext();
  promptAction: PromptAction = this.uiContext.getPromptAction();

  // 获取用户授权
  requestForNotification() {
    let context = this.getUIContext().getHostContext() as common.UIAbilityContext;
    notificationManager.isNotificationEnabled().then((data: boolean) => {
      console.info(`${DOMAIN_NUMBER}, ${TAG}, isNotificationEnabled success, data: ${data}`);
      if (!data) {
        notificationManager.requestEnableNotification(context).then(() => {
          this.promptAction.openToast({
            message: '请求通知授权成功',
            duration: 2000,
          });
          console.info(`${DOMAIN_NUMBER}, ${TAG}, [ANS] requestEnableNotification success`);
        }).catch((err: BusinessError) => {
          if (1600004 == err.code) {
            this.promptAction.openToast({
              message: '请求通知授权失败',
              duration: 2000,
            });
            console.error(`${DOMAIN_NUMBER}, ${TAG},
              [ANS] requestEnableNotification refused, code is ${err.code}, message is ${err.message}`);
          } else {
            console.error(`${DOMAIN_NUMBER}, ${TAG},
              [ANS] requestEnableNotification failed, code is ${err.code}, message is ${err.message}`);
          }
        });
      }
    }).catch((err: BusinessError) => {
      console.error(`${DOMAIN_NUMBER}, ${TAG}, isNotificationEnabled fail, code is ${err.code}, message is ${err.message}`);
    });
  }

  // 构造NotificationRequest对象，发布通知
  notification(title: string, message: string) {
    let notificationRequest: notificationManager.NotificationRequest = {
      id: 1,
      content: {
        notificationContentType: notificationManager.ContentType.NOTIFICATION_CONTENT_BASIC_TEXT, // 普通文本类型通知
        normal: {
          title: title,
          text: message,
          additionalText: 'test_additionalText',
        }
      }
    };
    notificationManager.publish(notificationRequest, (err: BusinessError) => {
      if (err) {
        console.error(`${DOMAIN_NUMBER}, ${TAG}, Failed to publish notification. Code is ${err.code}, message is ${err.message}`);
        this.promptAction.openToast({
          message: '请求通知授权成功',
          duration: 2000,
        });
        return;
      } else {
        console.info(`${DOMAIN_NUMBER}, ${TAG}, Succeeded in publishing notification.`);
        this.promptAction.openToast({
          message: '发布通知成功',
          duration: 2000,
        });
      }
    });
  }

  // 获取二次授权
  openNotification(){
    let context = this.getUIContext().getHostContext() as common.UIAbilityContext;
    notificationManager.isNotificationEnabled().then((data: boolean) => {
      console.info(`${DOMAIN_NUMBER}, ${TAG}, "isNotificationEnabled success, data:${data} `);
      if(!data){
        notificationManager.openNotificationSettings(context).then(() => {
          console.info(`${DOMAIN_NUMBER}, ${TAG}, [ANS] openNotificationSettings success`);
        }).catch((err: BusinessError) => {
          console.error(`${DOMAIN_NUMBER}, ${TAG}, [ANS] openNotificationSettings failed, code is ${err.code}, message is ${err.message}`);
        });
      }
    }).catch((err: BusinessError) => {
      console.error(`${DOMAIN_NUMBER}, ${TAG}, isNotificationEnabled fail, code is ${err.code}, message is ${err.message}`);
    });
  }

  aboutToAppear(): void {
    this.requestForNotification();
    this.openNotification();
  }

  build() {
    Column() {
      Button('发布通知').onClick(() => {
        let title = '这是一个标题';
        let message = '这是一条通知';
        this.notification(title, message);
      });
    }
    .width('100%')
    .height('100%')
    .justifyContent(FlexAlign.Center);
  }
}

常见FAQ

Q：APP退至后台到被挂起的这段时间内，是否仍然可以发起本地通知？

A：APP被退至后台，仍有若干时间才会被系统挂起（不可靠，3-10s）；在被挂起前，APP仍然可以发送本地通知，但依赖这种机制不可靠，建议在被退至后台时就切换到Push kit进行通知的模式。

总结