多端协同

功能描述

多端协同主要包括如下场景：

多端协同流程

多端协同流程如下图所示。

图1 多端协同流程图   hop-multi-device-collaboration

约束限制

  • 由于“多端协同任务管理”能力尚未具备，开发者当前只能通过开发系统应用获取设备列表，不支持三方应用接入。

  • 多端协同需遵循分布式跨设备组件启动规则。

  • 为了获得最佳体验，使用want传输的数据建议在100KB以下。

通过跨设备启动UIAbility和ServiceExtensionAbility组件实现多端协同（无返回数据）

在设备A上通过发起端应用提供的启动按钮，启动设备B上指定的UIAbility与ServiceExtensionAbility。

接口说明

表1 跨设备启动API接口功能介绍

接口名 描述
startAbility(want: Want, callback: AsyncCallback<void>): void; 启动UIAbility和ServiceExtensionAbility（callback形式）。
stopServiceExtensionAbility(want: Want, callback: AsyncCallback<void>): void; 退出启动的ServiceExtensionAbility（callback形式）。
stopServiceExtensionAbility(want: Want): Promise<void>; 退出启动的ServiceExtensionAbility（Promise形式）。

开发步骤

  1. 需要申请ohos.permission.DISTRIBUTED_DATASYNC权限，配置方式请参见配置文件权限声明。

  2. 同时需要在应用首次启动时弹窗向用户申请授权，使用方式请参见向用户申请授权。

  3. 获取目标设备的设备ID。

    import deviceManager from '@ohos.distributedDeviceManager';
import hilog from '@ohos.hilog';

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

let dmClass: deviceManager.DeviceManager;

function initDmClass(): void {
  // 其中createDeviceManager接口为系统API
  try {
    dmClass = deviceManager.createDeviceManager('com.samples.stagemodelabilitydevelop');
    hilog.info(DOMAIN_NUMBER, TAG, JSON.stringify(dmClass) ?? '');
  } catch (err) {
    hilog.error(DOMAIN_NUMBER, TAG, 'createDeviceManager err: ' + JSON.stringify(err));
  };
}

function getRemoteDeviceId(): string | undefined {
  if (typeof dmClass === 'object' && dmClass !== null) {
    let list = dmClass.getAvailableDeviceListSync();
    hilog.info(DOMAIN_NUMBER, TAG, JSON.stringify(dmClass), JSON.stringify(list));
    if (typeof (list) === 'undefined' || typeof (list.length) === 'undefined') {
      hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: list is null');
      return;
    }
    if (list.length === 0) {
      hilog.info(DOMAIN_NUMBER, TAG, `getRemoteDeviceId err: list is empty`);
      return;
    }
    return list[0].networkId;
  } else {
    hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: dmClass is null');
    return;
  }
}

  4. 设置目标组件参数，调用startAbility()接口，启动UIAbility或ServiceExtensionAbility。

    import { BusinessError } from '@ohos.base';
import hilog from '@ohos.hilog';
import Want from '@ohos.app.ability.Want';
import deviceManager from '@ohos.distributedDeviceManager';
import common from '@ohos.app.ability.common';

const TAG: string = '[Page_CollaborateAbility]';
const DOMAIN_NUMBER: number = 0xFF00;
let dmClass: deviceManager.DeviceManager;

function getRemoteDeviceId(): string | undefined {
  if (typeof dmClass === 'object' && dmClass !== null) {
    let list = dmClass.getAvailableDeviceListSync();
    hilog.info(DOMAIN_NUMBER, TAG, JSON.stringify(dmClass), JSON.stringify(list));
    if (typeof (list) === 'undefined' || typeof (list.length) === 'undefined') {
      hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: list is null');
      return;
    }
    if (list.length === 0) {
      hilog.info(DOMAIN_NUMBER, TAG, `getRemoteDeviceId err: list is empty`);
      return;
    }
    return list[0].networkId;
  } else {
    hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: dmClass is null');
    return;
  }
};

@Entry
@Component
struct Page_CollaborateAbility {
  private context = getContext(this) as common.UIAbilityContext;

  build() {
    // ...
    Button('startAbility')
      .onClick(() => {
        let want: Want = {
          deviceId: getRemoteDeviceId(),
          bundleName: 'com.samples.stagemodelabilityinteraction',
          abilityName: 'CollaborateAbility',
      moduleName: 'entry' // moduleName非必选
        }
	   // context为发起端UIAbility的AbilityContext
        this.context.startAbility(want).then(() => {
    		// ...
        }).catch((err: BusinessError) => {
    		// ...
          hilog.error(DOMAIN_NUMBER, TAG, `startAbility err: ` + JSON.stringify(err));
        });
      }
      )
  }
}

  5. 当设备A发起端应用不需要设备B上的ServiceExtensionAbility时，可调用stopServiceExtensionAbility接口退出。（该接口不支持UIAbility的退出，UIAbility由用户手动通过任务管理退出）

    import Want from '@ohos.app.ability.Want';
import hilog from '@ohos.hilog';
import { BusinessError } from '@ohos.base';
import deviceManager from '@ohos.distributedDeviceManager';
import common from '@ohos.app.ability.common';

const TAG: string = '[Page_CollaborateAbility]';
const DOMAIN_NUMBER: number = 0xFF00;
let dmClass: deviceManager.DeviceManager;

function getRemoteDeviceId(): string | undefined {
  if (typeof dmClass === 'object' && dmClass !== null) {
    let list = dmClass.getAvailableDeviceListSync();
    hilog.info(DOMAIN_NUMBER, TAG, JSON.stringify(dmClass), JSON.stringify(list));
    if (typeof (list) === 'undefined' || typeof (list.length) === 'undefined') {
      hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: list is null');
      return;
    }
    if (list.length === 0) {
      hilog.info(DOMAIN_NUMBER, TAG, `getRemoteDeviceId err: list is empty`);
      return;
    }
    return list[0].networkId;
  } else {
    hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: dmClass is null');
    return;
  }
};

@Entry
@Component
struct Page_CollaborateAbility {
  private context = getContext(this) as common.UIAbilityContext;

  build() {
    // ...
    Button('stopServiceExtensionAbility')
      .onClick(() => {
        let want: Want = {
          deviceId: getRemoteDeviceId(),
          bundleName: 'com.example.myapplication',
          abilityName: 'FuncAbility',
          moduleName: 'module1', // moduleName非必选
        }
        // 退出由startAbility接口启动的ServiceExtensionAbility
        this.context.stopServiceExtensionAbility(want).then(() => {
          console.info("stop service extension ability success")
        }).catch((err: BusinessError) => {
          console.info("stop service extension ability err is " + JSON.stringify(err))
        })
      })
  }
}

通过跨设备启动UIAbility组件实现多端协同（获取返回数据）

在设备A上通过应用提供的启动按钮，启动设备B上指定的UIAbility，当设备B上的UIAbility退出后，会将返回值发回设备A上的发起端应用。

接口说明

表2 跨设备启动，返回结果数据API接口功能描述

接口名 描述
startAbilityForResult(want: Want, callback: AsyncCallback<AbilityResult>): void; 启动UIAbility并在该Ability退出的时候返回执行结果（callback形式）。
terminateSelfWithResult(parameter: AbilityResult, callback: AsyncCallback<void>): void; 停止UIAbility，配合startAbilityForResult使用，返回给接口调用方AbilityResult信息（callback形式）。
terminateSelfWithResult(parameter: AbilityResult): Promise<void>; 停止UIAbility，配合startAbilityForResult使用，返回给接口调用方AbilityResult信息（promise形式）。

开发步骤

  1. 需要申请ohos.permission.DISTRIBUTED_DATASYNC权限，配置方式请参见配置文件权限声明。

  2. 同时需要在应用首次启动时弹窗向用户申请授权，使用方式请参见向用户申请授权。

  3. 在发起端设置目标组件参数，调用startAbilityForResult()接口启动目标端UIAbility，异步回调中的data用于接收目标端UIAbility停止自身后返回给调用方UIAbility的信息。getRemoteDeviceId方法参照通过跨设备启动uiability和serviceextensionability组件实现多端协同无返回数据。

    import common from '@ohos.app.ability.common';
import hilog from '@ohos.hilog';
import { BusinessError } from '@ohos.base';
import Want from '@ohos.app.ability.Want';
import deviceManager from '@ohos.distributedDeviceManager';

const DOMAIN_NUMBER: number = 0xFF00;
const TAG: string = '[Page_CollaborateAbility]';
let dmClass: deviceManager.DeviceManager;

function getRemoteDeviceId(): string | undefined {
  if (typeof dmClass === 'object' && dmClass !== null) {
    let list = dmClass.getAvailableDeviceListSync();
    hilog.info(DOMAIN_NUMBER, TAG, JSON.stringify(dmClass), JSON.stringify(list));
    if (typeof (list) === 'undefined' || typeof (list.length) === 'undefined') {
      hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: list is null');
      return;
    }
    if (list.length === 0) {
      hilog.info(DOMAIN_NUMBER, TAG, `getRemoteDeviceId err: list is empty`);
      return;
    }
    return list[0].networkId;
  } else {
    hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: dmClass is null');
    return;
  }
};

@Entry
@Component
struct Page_CollaborateAbility {
  private context = getContext(this) as common.UIAbilityContext;

  build() {
    // ...
    Button('多端协同有返回数据')
      .onClick(()=>{
        let want: Want = {
          deviceId: getRemoteDeviceId(),
          bundleName: 'com.samples.stagemodelabilityinteraction',
          abilityName: 'CollaborateAbility',
          moduleName: 'entry' // moduleName非必选
        };
        // context为发起端UIAbility的AbilityContext
        this.context.startAbilityForResult(want).then((data) => {
          // ...
        }).catch((error: BusinessError) => {
          hilog.error(DOMAIN_NUMBER, TAG, `startAbilityForResult err: ` + JSON.stringify(error));
        })
      }
      )
  }
}

  4. 在目标端UIAbility任务完成后，调用terminateSelfWithResult()方法，将数据返回给发起端的UIAbility。

    import common from '@ohos.app.ability.common';
import hilog from '@ohos.hilog';
import { BusinessError } from '@ohos.base';

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

@Entry
@Component
struct PageName {
  
   private context = getContext(this) as common.UIAbilityContext;
  
   build() {
     // ...
     Button('关闭多设备协同界面并返回数据')
       .onClick(()=>{
       const RESULT_CODE: number = 1001;
       // context为目标端UIAbility的AbilityContext
       this.context.terminateSelfWithResult(
         {
           resultCode: RESULT_CODE,
           want: {
             bundleName: 'ohos.samples.stagemodelabilitydevelop',
             abilityName: 'CollaborateAbility',
             moduleName: 'entry',
             parameters: {
               info: '来自Page_CollaborateAbility页面'
             }
           }
         },
         (err: BusinessError) => {
           hilog.info(DOMAIN_NUMBER, TAG, `terminateSelfWithResult err: ` + JSON.stringify(err));
         });
     })
   }
}

  5. 发起端UIAbility接收到目标端UIAbility返回的信息，对其进行处理。

    import common from '@ohos.app.ability.common';
import deviceManager from '@ohos.distributedDeviceManager';
import hilog from '@ohos.hilog';
import Want from '@ohos.app.ability.Want';
import { BusinessError } from '@ohos.base';

const TAG: string = '[Page_CollaborateAbility]';
const DOMAIN_NUMBER: number = 0xFF00;
let dmClass: deviceManager.DeviceManager;

function getRemoteDeviceId(): string | undefined {
  if (typeof dmClass === 'object' && dmClass !== null) {
    let list = dmClass.getAvailableDeviceListSync();
    hilog.info(DOMAIN_NUMBER, TAG, JSON.stringify(dmClass), JSON.stringify(list));
    if (typeof (list) === 'undefined' || typeof (list.length) === 'undefined') {
      hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: list is null');
      return;
    }
    if (list.length === 0) {
      hilog.info(DOMAIN_NUMBER, TAG, `getRemoteDeviceId err: list is empty`);
      return;
    }
    return list[0].networkId;
  } else {
    hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: dmClass is null');
    return;
  }
};

@Entry
@Component
struct PageName {
  private context = getContext(this) as common.UIAbilityContext;

  build() {
    // ...
    Button('多端协同有返回数据')
      .onClick(() => {
        let want: Want = {
          deviceId: getRemoteDeviceId(),
          bundleName: 'com.samples.stagemodelabilityinteraction',
          abilityName: 'CollaborateAbility',
          moduleName: 'entry' // moduleName非必选
        };
        const RESULT_CODE: number = 1001;
        // ...
        // context为调用方UIAbility的UIAbilityContext
        this.context.startAbilityForResult(want).then((data) => {
          if (data?.resultCode === RESULT_CODE) {
            // 解析目标端UIAbility返回的信息
            let info = data.want?.parameters?.info;
            // ...
          }
        }).catch((error: BusinessError) => {
          // ...
        })
      }
      )
  }
}

通过跨设备连接ServiceExtensionAbility组件实现多端协同

系统应用可以通过connectServiceExtensionAbility()跨设备连接一个服务，实现跨设备远程调用。比如：分布式游戏场景，平板作为遥控器，智慧屏作为显示器。

接口说明

表3 跨设备连接API接口功能介绍

接口名 描述
connectServiceExtensionAbility(want: Want, options: ConnectOptions): number; 连接ServiceExtensionAbility。
disconnectServiceExtensionAbility(connection: number, callback:AsyncCallback<void>): void; 断开连接（callback形式）。
disconnectServiceExtensionAbility(connection: number): Promise<void>; 断开连接（promise形式）。

开发步骤

  1. 需要申请ohos.permission.DISTRIBUTED_DATASYNC权限，配置方式请参见配置文件权限声明。

  2. 同时需要在应用首次启动时弹窗向用户申请授权，使用方式请参见向用户申请授权。

  3. 如果已有后台服务，请直接进入下一步；如果没有，则实现一个后台服务（仅对系统应用开放）。

  4. 连接一个后台服务。

    • 实现IAbilityConnection接口。IAbilityConnection提供了以下方法供开发者实现：onConnect()是用来处理连接Service成功的回调，onDisconnect()是用来处理Service异常终止的回调，onFailed()是用来处理连接Service失败的回调。

    • 设置目标组件参数，包括目标设备ID、Bundle名称、Ability名称。

    • 调用connectServiceExtensionAbility发起连接。

    • 连接成功，收到目标设备返回的服务句柄。

    • 进行跨设备调用，获得目标端服务返回的结果。

      import common from '@ohos.app.ability.common';
import deviceManager from '@ohos.distributedDeviceManager';
import hilog from '@ohos.hilog';
import rpc from '@ohos.rpc';
import Want from '@ohos.app.ability.Want';
import { BusinessError } from '@ohos.base';

const TAG: string = '[Page_CollaborateAbility]';
const DOMAIN_NUMBER: number = 0xFF00;
const REQUEST_CODE = 1;
let dmClass: deviceManager.DeviceManager;
let connectionId: number;
let options: common.ConnectOptions = {
  onConnect(elementName, remote) {
    hilog.info(DOMAIN_NUMBER, TAG, 'onConnect callback');
    if (remote === null) {
      hilog.info(DOMAIN_NUMBER, TAG, `onConnect remote is null`);
      return;
    }
    let option = new rpc.MessageOption();
    let data = new rpc.MessageSequence();
    let reply = new rpc.MessageSequence();
    data.writeInt(99); // 开发者可发送data到目标端应用进行相应操作
    // @param code 表示客户端发送的服务请求代码。
    // @param data 表示客户端发送的{@link MessageSequence}对象。
    // @param reply 表示远程服务发送的响应消息对象。
    // @param options 指示操作是同步的还是异步的。
    //
    // @return 如果操作成功返回{@code true}； 否则返回 {@code false}。
    remote.sendMessageRequest(REQUEST_CODE, data, reply, option).then((ret: rpc.RequestResult) => {
      let errCode = reply.readInt(); // 在成功连接的情况下，会收到来自目标端返回的信息（100）
      let msg: number = 0;
      if (errCode === 0) {
        msg = reply.readInt();
      }
  // 成功连接后台服务
      hilog.info(DOMAIN_NUMBER, TAG, `sendRequest msg:${msg}`);
    }).catch((error: BusinessError) => {
      hilog.info(DOMAIN_NUMBER, TAG, `sendRequest failed, ${JSON.stringify(error)}`);
    });
  },
  onDisconnect(elementName) {
    hilog.info(DOMAIN_NUMBER, TAG, 'onDisconnect callback');
  },
  onFailed(code) {
    hilog.info(DOMAIN_NUMBER, TAG, 'onFailed callback');
  }
};

function getRemoteDeviceId(): string | undefined {
  if (typeof dmClass === 'object' && dmClass !== null) {
    let list = dmClass.getAvailableDeviceListSync();
    hilog.info(DOMAIN_NUMBER, TAG, JSON.stringify(dmClass), JSON.stringify(list));
    if (typeof (list) === 'undefined' || typeof (list.length) === 'undefined') {
      hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: list is null');
      return;
    }
    if (list.length === 0) {
      hilog.info(DOMAIN_NUMBER, TAG, `getRemoteDeviceId err: list is empty`);
      return;
    }
    return list[0].networkId;
  } else {
    hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: dmClass is null');
    return;
  }
}

@Entry
@Component
struct PageName {
  private context = getContext(this) as common.UIAbilityContext;
  build() {
    // ...
    Button('connectServiceExtensionAbility')
      .onClick(()=>{
        let want: Want = {
          'deviceId': getRemoteDeviceId(),
          'bundleName': 'com.samples.stagemodelabilityinteraction',
          'abilityName': 'ServiceExtAbility'
        };
        // 建立连接后返回的Id需要保存下来，在解绑服务时需要作为参数传入
        connectionId = this.context.connectServiceExtensionAbility(want, options);
      })
  }
}

      getRemoteDeviceId方法参照通过跨设备启动uiability和serviceextensionability组件实现多端协同无返回数据。

  5. 断开连接。调用disconnectServiceExtensionAbility()断开与后台服务的连接。

    import common from '@ohos.app.ability.common';
import { BusinessError } from '@ohos.base';
import hilog from '@ohos.hilog';
import Want from '@ohos.app.ability.Want';
import rpc from '@ohos.rpc';
import IdlServiceExtProxy from '../IdlServiceExt/idl_service_ext_proxy';

let connectionId: number;
const TAG: string = '[Page_ServiceExtensionAbility]';
const DOMAIN_NUMBER: number = 0xFF00;
let want: Want = {
  deviceId: '',
  bundleName: 'com.samples.stagemodelabilitydevelop',
  abilityName: 'ServiceExtAbility'
};

let options: common.ConnectOptions = {
  onConnect(elementName, remote: rpc.IRemoteObject): void {
    hilog.info(DOMAIN_NUMBER, TAG, 'onConnect callback');
    if (remote === null) {
      hilog.info(DOMAIN_NUMBER, TAG, 'onConnect remote is null');
      return;
    }
    let serviceExtProxy: IdlServiceExtProxy = new IdlServiceExtProxy(remote);
    // 通过接口调用的方式进行通信，屏蔽了RPC通信的细节，简洁明了
    serviceExtProxy.processData(1, (errorCode: number, retVal: number) => {
      hilog.info(DOMAIN_NUMBER, TAG, `processData, errorCode: ${errorCode}, retVal: ${retVal}`);
    });
    serviceExtProxy.insertDataToMap('theKey', 1, (errorCode: number) => {
      hilog.info(DOMAIN_NUMBER, TAG, `insertDataToMap, errorCode: ${errorCode}`);
    })
  },
  onDisconnect(elementName): void {
    hilog.info(DOMAIN_NUMBER, TAG, 'onDisconnect callback');
  },
  onFailed(code: number): void {
    hilog.info(DOMAIN_NUMBER, TAG, 'onFailed callback', JSON.stringify(code));
  }
};

@Entry
@Component
struct PageName {
  private context = getContext(this) as common.UIAbilityContext;

  build() {
    // ...
    Button('disconnectServiceExtensionAbility')
      .onClick(() => {
        this.context.disconnectServiceExtensionAbility(connectionId).then(() => {
          connectionId = this.context.connectServiceExtensionAbility(want, options);
          hilog.info(DOMAIN_NUMBER, TAG, 'disconnectServiceExtensionAbility success');
          // 成功断连后台服务
        }).catch((error: BusinessError) => {
          hilog.error(DOMAIN_NUMBER, TAG, 'disconnectServiceExtensionAbility failed');
        })
      })
  }
}

通过跨设备Call调用实现多端协同

跨设备Call调用的基本原理与设备内Call调用相同，请参见通过Call调用实现UIAbility交互（仅对系统应用开放）。

下面介绍跨设备Call调用实现多端协同的方法。

接口说明

表4 Call API接口功能介绍

接口名 描述
startAbilityByCall(want: Want): Promise<Caller>; 启动指定UIAbility至前台或后台，同时获取其Caller通信接口，调用方可使用Caller与被启动的Ability进行通信。
on(method: string, callback: CalleeCallBack): void 通用组件Callee注册method对应的callback方法。
off(method: string): void 通用组件Callee解注册method的callback方法。
call(method: string, data: rpc.Parcelable): Promise<void> 向通用组件Callee发送约定序列化数据。
callWithResult(method: string, data: rpc.Parcelable): Promise<rpc.MessageSequence> 向通用组件Callee发送约定序列化数据, 并将Callee返回的约定序列化数据带回。
release(): void 释放通用组件的Caller通信接口。
on(type: "release", callback: OnReleaseCallback): void 注册通用组件通信断开监听通知。

开发步骤

  1. 需要申请ohos.permission.DISTRIBUTED_DATASYNC权限，配置方式请参见配置文件权限声明。

  2. 同时需要在应用首次启动时弹窗向用户申请授权，使用方式请参见向用户申请授权。

  3. 创建被调用端UIAbility。 被调用端UIAbility需要实现指定方法的数据接收回调函数、数据的序列化及反序列化方法。在需要接收数据期间，通过on接口注册监听，无需接收数据时通过off接口解除监听。

    1. 配置UIAbility的启动模式。 配置module.json5，将CalleeAbility配置为单实例"singleton"。
Json字段 字段说明
“launchType” Ability的启动模式，设置为"singleton"类型。 
     UIAbility配置标签示例如下：

     
     ```json
     "abilities":[{
         "name": ".CalleeAbility",
         "srcEntry": "./ets/CalleeAbility/CalleeAbility.ts",
         "launchType": "singleton",
         "description": "$string:CalleeAbility_desc",
         "icon": "$media:icon",
         "label": "$string:CalleeAbility_label",
         "exported": true
     }]
     ```
 2. 导入UIAbility模块。
    
     ```ts
     import UIAbility from '@ohos.app.ability.UIAbility';
     ```
 3. 定义约定的序列化数据。
     调用端及被调用端发送接收的数据格式需协商一致，如下示例约定数据由number和string组成。

     
     ```ts
     import rpc from '@ohos.rpc'
     class MyParcelable {
       num: number = 0;
       str: string = '';
     
       constructor(num: number, string: string) {
         this.num = num;
         this.str = string;
       }
     
       mySequenceable(num: number, string: string): void {
         this.num = num;
         this.str = string;
       }
     
       marshalling(messageSequence: rpc.MessageSequence): boolean {
         messageSequence.writeInt(this.num);
         messageSequence.writeString(this.str);
         return true;
       };
     
       unmarshalling(messageSequence: rpc.MessageSequence): boolean {
         this.num = messageSequence.readInt();
         this.str = messageSequence.readString();
         return true;
       };
     };
     ```
 4. 实现Callee.on监听及Callee.off解除监听。
       如下示例在Ability的onCreate注册MSG_SEND_METHOD监听，在onDestroy取消监听，收到序列化数据后作相应处理并返回。应用开发者根据实际业务需要做相应处理。
       
     ```ts
     import type AbilityConstant from '@ohos.app.ability.AbilityConstant';
     import UIAbility from '@ohos.app.ability.UIAbility';
     import type Want from '@ohos.app.ability.Want';
     import hilog from '@ohos.hilog';
     import type rpc from '@ohos.rpc';
     import type { Caller } from '@ohos.app.ability.UIAbility';
	 
     const TAG: string = '[CalleeAbility]';
     const MSG_SEND_METHOD: string = 'CallSendMsg';
     const DOMAIN_NUMBER: number = 0xFF00;
	 
     class MyParcelable {
       num: number = 0;
       str: string = '';
	 
       constructor(num: number, string: string) {
         this.num = num;
         this.str = string;
       };
	 
       mySequenceable(num: number, string: string): void {
         this.num = num;
         this.str = string;
       };
	 
       marshalling(messageSequence: rpc.MessageSequence): boolean {
         messageSequence.writeInt(this.num);
         messageSequence.writeString(this.str);
         return true;
       };
	 
       unmarshalling(messageSequence: rpc.MessageSequence): boolean {
         this.num = messageSequence.readInt();
         this.str = messageSequence.readString();
         return true;
       };
     };
	 
     function sendMsgCallback(data: rpc.MessageSequence): rpc.Parcelable {
       hilog.info(DOMAIN_NUMBER, TAG, '%{public}s', 'CalleeSortFunc called');
	 
       // 获取Caller发送的序列化数据
       let receivedData: MyParcelable = new MyParcelable(0, '');
       data.readParcelable(receivedData);
       hilog.info(DOMAIN_NUMBER, TAG, '%{public}s', `receiveData[${receivedData.num}, ${receivedData.str}]`);
       let num: number = receivedData.num;
	 
       // 作相应处理
       // 返回序列化数据result给Caller
       return new MyParcelable(num + 1, `send ${receivedData.str} succeed`) as rpc.Parcelable;
     }
	 
     export default class CalleeAbility extends UIAbility {
       caller: Caller | undefined;
	 
       onCreate(want: Want, launchParam: AbilityConstant.LaunchParam): void {
         try {
           this.callee.on(MSG_SEND_METHOD, sendMsgCallback);
         } catch (error) {
           hilog.error(DOMAIN_NUMBER, TAG, '%{public}s', `Failed to register. Error is ${error}`)
         };
       }
	 
       onDestroy(): void {
         try {
           this.callee.off(MSG_SEND_METHOD);
           hilog.info(DOMAIN_NUMBER, TAG, '%{public}s', 'Callee OnDestroy');
           this.releaseCall();
         } catch (error) {
           hilog.error(DOMAIN_NUMBER, TAG, '%{public}s', `Failed to register. Error is ${error}`)
         };
       }
     }
     ```

  1. 获取Caller接口，访问被调用端UIAbility。

    1. 导入UIAbility模块。

      import UIAbility from '@ohos.app.ability.UIAbility';

    2. 获取Caller通信接口。 Ability的context属性实现了startAbilityByCall方法，用于获取指定通用组件的Caller通信接口。如下示例通过this.context获取Ability实例的context属性，使用startAbilityByCall拉起Callee被调用端并获取Caller通信接口，注册Caller的onRelease和onRemoteStateChange监听。应用开发者根据实际业务需要做相应处理。

      import { Caller } from '@ohos.app.ability.UIAbility';
import { BusinessError } from '@ohos.base';
import common from '@ohos.app.ability.common';
import deviceManager from '@ohos.distributedDeviceManager';
import hilog from '@ohos.hilog';
   
const TAG: string = '[Page_CollaborateAbility]';
const DOMAIN_NUMBER: number = 0xFF00;
let caller: Caller | undefined;
let dmClass: deviceManager.DeviceManager;
   
function getRemoteDeviceId(): string | undefined {
  if (typeof dmClass === 'object' && dmClass !== null) {
    let list = dmClass.getAvailableDeviceListSync();
    hilog.info(DOMAIN_NUMBER, TAG, JSON.stringify(dmClass), JSON.stringify(list));
    if (typeof (list) === 'undefined' || typeof (list.length) === 'undefined') {
      hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: list is null');
      return;
    }
    if (list.length === 0) {
      hilog.info(DOMAIN_NUMBER, TAG, `getRemoteDeviceId err: list is empty`);
      return;
    }
    return list[0].networkId;
  } else {
    hilog.info(DOMAIN_NUMBER, TAG, 'getRemoteDeviceId err: dmClass is null');
    return;
  }
}
   
@Entry
@Component
struct Page_CollaborateAbility {
  private context = getContext(this) as common.UIAbilityContext;
   
  build() {
    // ...
    Button('多端协同有返回数据')
      .onClick(() => {
        this.context.startAbilityByCall({
          deviceId: getRemoteDeviceId(),
          bundleName: 'com.samples.stagemodelabilityinteraction',
          abilityName: 'CalleeAbility'
        }).then((data) => {
          if (data !== null) {
            caller = data;
            hilog.info(DOMAIN_NUMBER, TAG, 'get remote caller success');
            // 注册caller的release监听
            caller.onRelease((msg) => {
              hilog.info(DOMAIN_NUMBER, TAG, `remote caller onRelease is called ${msg}`);
            })
            hilog.info(DOMAIN_NUMBER, TAG, 'remote caller register OnRelease succeed');
            // 注册caller的协同场景下跨设备组件状态变化监听通知
            try {
              caller.onRemoteStateChange((str) => {
                hilog.info(DOMAIN_NUMBER, TAG, 'Remote state changed ' + str);
              });
            } catch (error) {
              hilog.info(DOMAIN_NUMBER, TAG, `Caller.onRemoteStateChange catch error, error.code: ${JSON.stringify(error.code)}, error.message: ${JSON.stringify(error.message)}`);
            };
          }
        }).catch((error: BusinessError) => {
          hilog.error(DOMAIN_NUMBER, TAG, `get remote caller failed with ${error}`);
        });
      }
      )
  }
}

      getRemoteDeviceId方法参照通过跨设备启动uiability和serviceextensionability组件实现多端协同无返回数据。

  2. 向被调用端UIAbility发送约定序列化数据。

    1. 向被调用端发送Parcelable数据有两种方式，一种是不带返回值，一种是获取被调用端返回的数据，method以及序列化数据需要与被调用端协商一致。如下示例调用Call接口，向Callee被调用端发送数据。

      import UIAbility, { Caller } from '@ohos.app.ability.UIAbility';
import type rpc from '@ohos.rpc';
   
const MSG_SEND_METHOD: string = 'CallSendMsg';
class MyParcelable {
  num: number = 0;
  str: string = '';
   
  constructor(num: number, string: string) {
    this.num = num;
    this.str = string;
  };
   
  mySequenceable(num: number, string: string): void {
    this.num = num;
    this.str = string;
  };
   
  marshalling(messageSequence: rpc.MessageSequence): boolean {
    messageSequence.writeInt(this.num);
    messageSequence.writeString(this.str);
    return true;
  };
   
  unmarshalling(messageSequence: rpc.MessageSequence): boolean {
    this.num = messageSequence.readInt();
    this.str = messageSequence.readString();
    return true;
  };
};
   
export default class EntryAbility extends UIAbility {
  // ...
  caller: Caller | undefined;
  async onButtonCall(): Promise<void> {
    try {
      let msg: MyParcelable = new MyParcelable(1, 'origin_Msg');
      if (this.caller) {
        await this.caller.call(MSG_SEND_METHOD, msg);
      }
    } catch (error) {
      hilog.info(DOMAIN_NUMBER, TAG, `caller call failed with ${error}`);
    };
  }
  // ...
}

    2. 如下示例调用CallWithResult接口，向Callee被调用端发送待处理的数据originMsg，并将’CallSendMsg’方法处理完毕的数据赋值给backMsg。

      import UIAbility, { Caller } from '@ohos.app.ability.UIAbility';
import rpc from '@ohos.rpc';

const MSG_SEND_METHOD: string = 'CallSendMsg';
let originMsg: string = '';
let backMsg: string = '';

class MyParcelable {
  num: number = 0;
  str: string = '';

  constructor(num: number, string: string) {
    this.num = num;
    this.str = string;
  };

  mySequenceable(num: number, string: string): void {
    this.num = num;
    this.str = string;
  };

  marshalling(messageSequence: rpc.MessageSequence): boolean {
    messageSequence.writeInt(this.num);
    messageSequence.writeString(this.str);
    return true;
  };

  unmarshalling(messageSequence: rpc.MessageSequence): boolean {
    this.num = messageSequence.readInt();
    this.str = messageSequence.readString();
    return true;
  };
};

export default class EntryAbility extends UIAbility {
  // ...
  caller: Caller | undefined;
  async onButtonCallWithResult(originMsg: string, backMsg: string): Promise<void> {
    try {
      let msg: MyParcelable = new MyParcelable(1, originMsg);
      if (this.caller) {
        const data = await this.caller.callWithResult(MSG_SEND_METHOD, msg);
        hilog.info(DOMAIN_NUMBER, TAG, 'caller callWithResult succeed');
        let result: MyParcelable = new MyParcelable(0, '');
        data.readParcelable(result);
        backMsg = result.str;
        hilog.info(DOMAIN_NUMBER, TAG, `caller result is [${result.num}, ${result.str}]`);
      }
    } catch (error) {
      hilog.info(DOMAIN_NUMBER, TAG, `caller callWithResult failed with ${error}`);
    };
  }
  // ...
}

  3. 释放Caller通信接口。 Caller不再使用后，应用开发者可以通过release接口释放Caller。

    import UIAbility, { Caller } from '@ohos.app.ability.UIAbility';

export default class EntryAbility extends UIAbility {
  caller: Caller | undefined;
  releaseCall(): void {
    try {
      if (this.caller) {
        this.caller.release();
        this.caller = undefined;
      }
      hilog.info(DOMAIN_NUMBER, TAG, 'caller release succeed');
    } catch (error) {
      hilog.info(DOMAIN_NUMBER, TAG, `caller release failed with ${error}`);
    };
  }
}