HarmonyOS 鸿蒙Next ArkTS语言教程入门学习第59天，创建，启动，连接ServiceAbility。

HarmonyOS 鸿蒙Next ArkTS语言教程入门学习第59天，创建，启动，连接ServiceAbility。 1、创建ServiceAbility

创建ServiceAbility。

重写ServiceAbility的生命周期方法，添加其他Ability请求与ServiceAbility交互时的处理方法。

import rpc from "@ohos.rpc"

class FirstServiceAbilityStub extends rpc.RemoteObject {
  constructor(des: any) {
    if (typeof des === 'string') {
      super(des)
    } else {
      return
    }
  }
}

export default {
  onStart() {
    console.info('ServiceAbility onStart')
  },
  onStop() {
    console.info('ServiceAbility onStop')
  },
  onCommand(want, startId) {
    console.info('ServiceAbility onCommand')
  },
  onConnect(want) {
    console.info('ServiceAbility onConnect' + want)
    return new FirstServiceAbilityStub('test')
  },
  onDisconnect(want) {
    console.info('ServiceAbility onDisconnect' + want)
  }
}

2.注册ServiceAbility。

ServiceAbility需要在应用配置文件config.json中进行注册，注册类型type需要设置为service。"visible"属性表示ServiceAbility是否可以被其他应用调用，true表示可以被其他应用调用，false表示不能被其他应用调用（仅应用内可以调用）。若ServiceAbility需要被其他应用调用，注册ServiceAbility时需要设置"visible"为true，同时需要设置支持关联启动。

{
  "module": {
    "abilities": [
      {
        "name": ".ServiceAbility",
        "srcLanguage": "ets",
        "srcPath": "ServiceAbility",
        "icon": "$media:icon",
        "description": "hap sample empty service",
        "type": "service",
        "visible": true
      }
    ]
  }
}

2、启动ServiceAbility

ServiceAbility的启动与其他Ability并无区别，应用开发者可以在PageAbility中通过featureAbility的startAbility接口拉起ServiceAbility，在ServiceAbility中通过particleAbility的startAbility接口拉起ServiceAbility。

如下示例展示了在PageAbility中通过startAbility启动bundleName为"com.example.myapplication"，abilityName为"ServiceAbility"的ServiceAbility的方法。启动FA模型的ServiceAbility时，需要在abilityName前拼接bundleName字符串。

import featureAbility from '@ohos.ability.featureAbility'

async function startServiceAbility() {
  try {
    console.info('Begin to start ability')
    let param = {
      want: {
        bundleName: "com.example.myapplication",
        abilityName: "com.example.myapplication.ServiceAbility"
      }
    }
    await featureAbility.startAbility(param)
    console.info(`Start ability succeed`)
  } catch (error) {
    console.error('Start ability failed with ' + error)
  }
}

执行上述代码后，Ability将通过startAbility() 方法来启动ServiceAbility。

如果ServiceAbility尚未运行，则系统会先调用onStart()来初始化ServiceAbility，再回调Service的onCommand()方法来启动ServiceAbility。

如果ServiceAbility正在运行，则系统会直接回调ServiceAbility的onCommand()方法来启动ServiceAbility。

3、连接ServiceAbility

如果ServiceAbility需要与PageAbility或其他应用的ServiceAbility进行交互，则须创建用于连接的Connection。ServiceAbility支持其他Ability通过connectAbility()方法与其进行连接。PageAbility的connectAbility方法定义在featureAbility中，ServiceAbility的connectAbility方法定义在particleAbility中。在使用connectAbility()处理回调时，需要传入目标Service的Want与IAbilityConnection的实例。IAbilityConnection提供了以下方法供开发者实现。

PageAbility创建连接本地ServiceAbility回调实例的代码以及连接本地ServiceAbility的示例代码如下：

import rpc from "@ohos.rpc"
import prompt from '@system.prompt'
import featureAbility from '@ohos.ability.featureAbility'

let option = {
  onConnect: function onConnectCallback(element, proxy) {
    console.info(`onConnectLocalService onConnectDone`)
    if (proxy === null) {
      prompt.showToast({
        message: "Connect service failed"
      })
      return
    }
    let data = rpc.MessageParcel.create()
    let reply = rpc.MessageParcel.create()
    let option = new rpc.MessageOption()
    data.writeInterfaceToken("connect.test.token")
    proxy.sendRequest(0, data, reply, option)
    prompt.showToast({
      message: "Connect service success"
    })
  },
  onDisconnect: function onDisconnectCallback(element) {
    console.info(`onConnectLocalService onDisconnectDone element:${element}`)
    prompt.showToast({
      message: "Disconnect service success"
    })
  },
  onFailed: function onFailedCallback(code) {
    console.info(`onConnectLocalService onFailed errCode:${code}`)
    prompt.showToast({
      message: "Connect local service onFailed"
    })
  }
}

let request = {
  bundleName: "com.example.myapplication",
  abilityName: "com.example.myapplication.ServiceAbility",
}
let connId = featureAbility.connectAbility(request, option)

同时，Service侧也需要在onConnect()时返回IRemoteObject，从而定义与Service进行通信的接口。onConnect()需要返回一个IRemoteObject对象。HarmonyOS提供了IRemoteObject的默认实现，开发者可以通过继承rpc.RemoteObject来创建自定义的实现类。

Service侧把自身的实例返回给调用侧的示例代码如下：

import rpc from "@ohos.rpc"

class FirstServiceAbilityStub extends rpc.RemoteObject {
  constructor(des: any) {
    if (typeof des === 'string') {
      super(des)
    } else {
      return
    }
  }

  onRemoteRequest(code: number, data: any, reply: any, option: any) {
    console.info(`onRemoteRequest called`)
    if (code === 1) {
      let string = data.readString()
      console.info(`string=${string}`)
      let result = Array.from(string).sort().join('')
      console.info(`result=${result}`)
      reply.writeString(result)
    } else {
      console.info(`unknown request code`)
    }
    return true
  }
}