【HarmonyOS】【ArkUI】在Service中使用Emitter_ohos.events.emitter

 参考资料

1.相关基础知识：触发器Emitter
2.启动服务：ServiceAbility开发

开发步骤

第一步：开发界面，界面内容由一个按钮组件+文本组件构成，然后在按钮组件中添加点击事件，开启服务。代码如下：

import featureAbility from "@ohos.ability.featureAbility"
import emitter from '@ohos.events.emitter';
 
@Entry
@Component
struct Index {
  @State text: string = ""
 
  aboutToAppear() {
    var innerEvent = { eventId: 1002 }
    emitter.on(innerEvent, (eventData) => {
      let result = eventData.data.sum
      this.text = result
      console.log("计算的结果为:" + result)
    })
  }
 
  aboutToDisappear(){
    emitter.off(1002)
  }
 
  build() {
    Column() {
      Row() {
        Button("计算数组的和", { type: ButtonType.Normal })
      }
      .width("100%")
      .justifyContent(FlexAlign.Center)
      .height("20%")
      .alignItems(VerticalAlign.Center)
      .backgroundColor("#d5d5d5")
      .onClick(() => {
        console.log("按钮被点击")
        featureAbility.startAbility({
          want: {
            deviceId: "",
            bundleName: "com.zwc.myapplication",
            abilityName: "com.zwc.myapplication.ServiceAbility1",
          }
        })
      })
 
      Column() {
        Text("数组的和为:" + this.text)
          .fontSize(40)
          .fontColor(Color.Green)
          .width("100%")
          .textAlign(TextAlign.Center)
      }
      .width("100%")
      .height("80%")
      .backgroundColor("#FFCCaa")
    }
  }
}
 

第二步：新建服务类，在服务中完成数组计算，把值通过触发器传递至界面显示
一定要在config.json文件中，在module模块下配置触发器权限：

  "reqPermissions": [
      {
        "name": "ohos.permission.PUBLISH_AGENT_REMINDER"
      }
    ],

然后编写服务类，通过触发器的emmit方法把计算后的值发送至界面：
emitter.emit(innerEvent, eventData)

import hilog from '@ohos.hilog';
import emitter from '@ohos.events.emitter';
 
export default {
    onCommand(want, startId) {
        hilog.isLoggable(0x0000, 'testTag', hilog.LogLevel.DEBUG);
        hilog.debug(0x0000, 'testTag', '%{public}s', 'ServiceAbility onCommand');
 
        let myArrays: Array<number> = [10, 20, 30, 40, 50, 60]
        let sum: number = 0;
        for (let i = 0;i < myArrays.length; i++) {
            sum += myArrays[i]
        }
        hilog.debug(0x0000, 'testTag', '%{public}s', '数据的和是：' + sum);
 
        var innerEvent = {
            eventId: 1002
        }
        var eventData = {
            data: {
                'sum': sum
            },
            priority: emitter.EventPriority.HIGH
        }
        hilog.debug(0x0000, 'testTag', '%{public}s', '发射器：' + JSON.stringify(eventData.data));
        emitter.emit(innerEvent, eventData)
        hilog.debug(0x0000, 'testTag', '%{public}s', '发成功');
    }
};

运行结果

欲了解更多更全技术文章，欢迎访问https://developer.huawei.com/consumer/cn/forum/?ha_source=zzh