开源鸿蒙 后台任务开发指导

  • 2022-08-09
  • 浏览 (824)

后台任务开发指导

场景介绍

应用或业务模块处于后台(无可见界面)时,如果有需要继续执行或者后续执行的业务,可基于业务类型,申请短时任务延迟挂起(Suspend)或者长时任务避免进入挂起状态。

短时任务

接口说明

表1 短时任务主要接口

接口名 描述
requestSuspendDelay(reason: string, callback: Callback<void>): DelaySuspendInfo 后台应用申请延迟挂起。
延迟挂起时间一般情况下默认值为180000,低电量时默认值为60000。
getRemainingDelayTime(requestId: number): Promise<number> 获取应用程序进入挂起状态前的剩余时间。
使用Promise形式返回。
cancelSuspendDelay(requestId: number): void 取消延迟挂起。

开发步骤

  1. 申请延迟挂起

    import backgroundTaskManager from '@ohos.backgroundTaskManager';
    
    
    let myReason = 'test requestSuspendDelay';
    let delayInfo = backgroundTaskManager.requestSuspendDelay(myReason, () => {
        console.info("Request suspension delay will time out.");
    });
    
    
    var id = delayInfo.requestId;
    console.info("requestId is: " + id);
    
  2. 获取进入挂起前的剩余时间

    backgroundTaskManager.getRemainingDelayTime(id).then( res => {
        console.log('promise => Operation getRemainingDelayTime succeeded. Data: ' + JSON.stringify(res));
    }).catch( err => {
        console.log('promise => Operation getRemainingDelayTime failed. Cause: ' + err.code);
    });
    
  3. 取消延迟挂起

    backgroundTaskManager.cancelSuspendDelay(id);
    

开发实例

import backgroundTaskManager from '@ohos.backgroundTaskManager';
let myReason = 'test requestSuspendDelay';

// 申请延迟挂起
let delayInfo = backgroundTaskManager.requestSuspendDelay(myReason, () => {
    console.info("Request suspension delay will time out.");
});

// 打印延迟挂起信息
var id = delayInfo.requestId;
var time = delayInfo.actualDelayTime;
console.info("The requestId is: " + id);
console.info("The actualDelayTime is: " + time);

// 获取应用程序进入挂起状态前的剩余时间
backgroundTaskManager.getRemainingDelayTime(id).then( res => {
    console.log('promise => Operation getRemainingDelayTime succeeded. Data: ' + JSON.stringify(res));
}).catch( err => {
    console.log('promise => Operation getRemainingDelayTime failed. Cause: ' + err.code);
});

// 取消延迟挂起
backgroundTaskManager.cancelSuspendDelay(id);

长时任务

权限

ohos.permission.KEEP_BACKGROUND_RUNNING

接口说明

表2 长时任务主要接口

接口名 描述
startBackgroundRunning(context: Context, bgMode: BackgroundMode, wantAgent: WantAgent): Promise<void> 服务启动后,向系统申请长时任务,使服务一直保持后台运行。
stopBackgroundRunning(context: Context): Promise<void> 停止后台长时任务的运行。

其中,wantAgent的信息详见(WantAgent

表3 后台模式类型

参数名 id值 描述 配置项
DATA_TRANSFER 1 数据传输 dataTransfer
AUDIO_PLAYBACK 2 音频播放 audioPlayback
AUDIO_RECORDING 3 录音 audioRecording
LOCATION 4 定位导航 location
BLUETOOTH_INTERACTION 5 蓝牙相关 bluetoothInteraction
MULTI_DEVICE_CONNECTION 6 多设备互联 multiDeviceConnection
WIFI_INTERACTION 7 WLAN相关(系统保留) wifiInteraction
VOIP 8 音视频通话(系统保留) voip
TASK_KEEPING 9 计算任务(仅供特定设备使用) taskKeeping

开发步骤

基于FA模型:

  1. 新建Api Version 8的工程后,在工程目录中右键选择“new” -> “Ability” -> “Service Ability” 快速创建Service Ability组件。并在config.json文件中配置长时任务权限、后台模式类型,其中Ability类型为“service”。

    "module": {
      "package": "com.example.myapplication",
      "abilities": [
        {
          "backgroundModes": [
            "dataTransfer",
            "location"
          ], // 后台模式类型
          "type": "service"  // ability类型为service
        }
      ],
      "reqPermissions": [
        {
          "name": "ohos.permission.KEEP_BACKGROUND_RUNNING"  // 长时任务权限
        }
      ]
    }
    
  2. 申请长时任务。

    import backgroundTaskManager from '@ohos.backgroundTaskManager';
    import featureAbility from '@ohos.ability.featureAbility';
    import wantAgent from '@ohos.wantAgent';
    
    
    let wantAgentInfo = {
        wants: [
            {
                bundleName: "com.example.myapplication",
                abilityName: "com.example.myapplication.MainAbility"
            }
        ],
        operationType: wantAgent.OperationType.START_ABILITY,
        requestCode: 0,
        wantAgentFlags: [wantAgent.WantAgentFlags.UPDATE_PRESENT_FLAG]
    };
    
    
    // 通过wantAgent模块的getWantAgent方法获取WantAgent对象
    wantAgent.getWantAgent(wantAgentInfo).then((wantAgentObj) => {
        backgroundTaskManager.startBackgroundRunning(featureAbility.getContext(),
            backgroundTaskManager.BackgroundMode.DATA_TRANSFER, wantAgentObj).then(() => {
            console.info("Operation startBackgroundRunning succeeded");
        }).catch((err) => {
            console.error("Operation startBackgroundRunning failed Cause: " + err);
        });
    });
    
  3. 停止长时任务。

    import backgroundTaskManager from '@ohos.backgroundTaskManager';
    import featureAbility from '@ohos.ability.featureAbility';
    
    
    backgroundTaskManager.stopBackgroundRunning(featureAbility.getContext()).then(() => {
        console.info("Operation stopBackgroundRunning succeeded");
    }).catch((err) => {
        console.error("Operation stopBackgroundRunning failed Cause: " + err);
    });
    
    
    

基于Stage模型:

  1. 新建Api Version 9的工程后,在工程目录中右键选择“New” -> “Ability” 快速创建Ability组件。并在module.json5文件中配置长时任务权限、后台模式类型。

    "module": {
      "abilities": [
        {
          "backgroundModes": [
            "dataTransfer",
            "location"
          ], // 后台模式类型
        }
      ],
      "requestPermissions": [
        {
          "name": "ohos.permission.KEEP_BACKGROUND_RUNNING"  // 长时任务权限
        }
      ]
    }
    
  2. 申请长时任务。

    import backgroundTaskManager from '@ohos.backgroundTaskManager';
    import wantAgent from '@ohos.wantAgent';
    
    
    let wantAgentInfo = {
        wants: [
            {
                bundleName: "com.example.myapplication",
                abilityName: "com.example.myapplication.MainAbility"
            }
        ],
        operationType: wantAgent.OperationType.START_ABILITY,
        requestCode: 0,
        wantAgentFlags: [wantAgent.WantAgentFlags.UPDATE_PRESENT_FLAG]
    };
    
    
    // 通过wantAgent模块的getWantAgent方法获取WantAgent对象
    wantAgent.getWantAgent(wantAgentInfo).then((wantAgentObj) => {
        backgroundTaskManager.startBackgroundRunning(this.context,
            backgroundTaskManager.BackgroundMode.DATA_TRANSFER, wantAgentObj).then(() => {
            console.info("Operation startBackgroundRunning succeeded");
        }).catch((err) => {
            console.error("Operation startBackgroundRunning failed Cause: " + err);
        });
    });
    
  3. 停止长时任务。

    import backgroundTaskManager from '@ohos.backgroundTaskManager';
    
    
    backgroundTaskManager.stopBackgroundRunning(this.context).then(() => {
        console.info("Operation stopBackgroundRunning succeeded");
    }).catch((err) => {
        console.error("Operation stopBackgroundRunning failed Cause: " + err);
    });
    
    
    

开发实例

基于FA模型:

基于FA的Service Ability使用,参考ServiceAbility开发指导

当不需要与后台执行的长时任务交互时,可以采用startAbility()方法启动Service Ability。并在Service Ability的onStart回调方法中,调用长时任务的申请接口,声明此服务需要在后台长时运行。当任务执行完,再调用长时任务取消接口,及时释放资源。

当需要与后台执行的长时任务交互时(如播放音乐等)。可以采用connectAbility()方法启动并连接Service Ability。在获取到服务的代理对象后,与服务进行通信,控制长时任务的申请和取消。

import backgroundTaskManager from '@ohos.backgroundTaskManager';
import featureAbility from '@ohos.ability.featureAbility';
import wantAgent from '@ohos.wantAgent';
import rpc from "@ohos.rpc";

function startBackgroundRunning() {
    let wantAgentInfo = {
        // 点击通知后,将要执行的动作列表
        wants: [
            {
                bundleName: "com.example.myapplication",
                abilityName: "com.example.myapplication.MainAbility"
            }
        ],
        // 点击通知后,动作类型
        operationType: wantAgent.OperationType.START_ABILITY,
        // 使用者自定义的一个私有值
        requestCode: 0,
        // 点击通知后,动作执行属性
        wantAgentFlags: [wantAgent.WantAgentFlags.UPDATE_PRESENT_FLAG]
    };

    // 通过wantAgent模块的getWantAgent方法获取WantAgent对象
    wantAgent.getWantAgent(wantAgentInfo).then((wantAgentObj) => {
        backgroundTaskManager.startBackgroundRunning(featureAbility.getContext(),
            backgroundTaskManager.BackgroundMode.DATA_TRANSFER, wantAgentObj).then(() => {
            console.info("Operation startBackgroundRunning succeeded");
        }).catch((err) => {
            console.error("Operation startBackgroundRunning failed Cause: " + err);
        });
    });
}

function stopBackgroundRunning() {
    backgroundTaskManager.stopBackgroundRunning(featureAbility.getContext()).then(() => {
        console.info("Operation stopBackgroundRunning succeeded");
    }).catch((err) => {
        console.error("Operation stopBackgroundRunning failed Cause: " + err);
    });
}

let mMyStub;

class MyStub extends rpc.RemoteObject {
    constructor(des) {
        if (typeof des === 'string') {
            super(des);
        } else {
            return null;
        }
    }
    onRemoteRequest(code, data, reply, option) {
        console.log('ServiceAbility onRemoteRequest called');
        // code 的具体含义用户自定义
        if (code === 1) {
            // 接收到申请长时任务的请求码
            startContinuousTask();
            // 此处执行具体长时任务
        } else if (code === 2) {
            // 接收到取消长时任务的请求码
            stopContinuousTask();
        } else {
            console.log('ServiceAbility unknown request code');
        }
        return true;
    }
}

export default {
    onStart(want) {
        console.info('ServiceAbility onStart');
        mMyStub = new MyStub("ServiceAbility-test");
        startBackgroundRunning();
        // 此处执行后台具体的长时任务。
        stopBackgroundRunning();
    },
    onStop() {
        console.info('ServiceAbility onStop');
    },
    onConnect(want) {
        console.info('ServiceAbility onConnect');
        return mMyStub;
    },
    onReconnect(want) {
        console.info('ServiceAbility onReconnect');
    },
    onDisconnect() {
        console.info('ServiceAbility onDisconnect');
    },
    onCommand(want, restart, startId) {
        console.info('ServiceAbility onCommand');
    }
};

基于Stage模型:

Stage模型的相关信息参考Stage模型综述。 当应用需要在后台执行长时任务时,可以通过Call的方式在后台创建并运行Ability。使用方式参考Call调用开发指导

import Ability from '@ohos.application.Ability'
import backgroundTaskManager from '@ohos.backgroundTaskManager';
import wantAgent from '@ohos.wantAgent';

let mContext = null;

function startContinuousTask() {
    let wantAgentInfo = {
        // 点击通知后,将要执行的动作列表
        wants: [
            {
                bundleName: "com.example.myapplication",
                abilityName: "com.example.myapplication.MainAbility"
            }
        ],
        // 点击通知后,动作类型
        operationType: wantAgent.OperationType.START_ABILITY,
        // 使用者自定义的一个私有值
        requestCode: 0,
        // 点击通知后,动作执行属性
        wantAgentFlags: [wantAgent.WantAgentFlags.UPDATE_PRESENT_FLAG]
    };

    // 通过wantAgent模块的getWantAgent方法获取WantAgent对象
    wantAgent.getWantAgent(wantAgentInfo).then((wantAgentObj) => {
        backgroundTaskManager.startBackgroundRunning(mContext,
            backgroundTaskManager.BackgroundMode.DATA_TRANSFER, wantAgentObj).then(() => {
            console.info("Operation startBackgroundRunning succeeded");
        }).catch((err) => {
            console.error("Operation startBackgroundRunning failed Cause: " + err);
        });
    });
}

function stopContinuousTask() {
    backgroundTaskManager.stopBackgroundRunning(mContext).then(() => {
        console.info("Operation stopBackgroundRunning succeeded");
    }).catch((err) => {
        console.error("Operation stopBackgroundRunning failed Cause: " + err);
    });
}

class MySequenceable {
    num: number = 0;
    str: String = "";

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

    marshalling(messageParcel) {
        messageParcel.writeInt(this.num);
        messageParcel.writeString(this.str);
        return true;
    }

    unmarshalling(messageParcel) {
        this.num = messageParcel.readInt();
        this.str = messageParcel.readString();
        return true;
    }
}

function sendMsgCallback(data) {
    console.info('BgTaskAbility funcCallBack is called ' + data)
    let receivedData = new Mysequenceable(0, "")
    data.readSequenceable(receivedData)
    console.info(`receiveData[${receivedData.num}, ${receivedData.str}]`)
    if (receivedData.str === 'start_bgtask') {
        startContinuousTask()
    } else if (receivedData.str === 'stop_bgtask') {
        stopContinuousTask();
    }
    return new Mysequenceable(10, "Callee test");
}

export default class BgTaskAbility extends Ability {
    onCreate(want, launchParam) {
        console.info("[Demo] BgTaskAbility onCreate")
        this.callee.on("test", sendMsgCallback);

        try {
            this.callee.on(MSG_SEND_METHOD, sendMsgCallback)
        } catch (error) {
            console.error(`${MSG_SEND_METHOD} register failed with error ${JSON.stringify(error)}`)
        }
        mContext = this.context;
    }

    onDestroy() {
        console.info("[Demo] BgTaskAbility onDestroy")
    }

    onWindowStageCreate(windowStage) {
        console.info("[Demo] BgTaskAbility onWindowStageCreate")

        windowStage.loadContent("pages/second").then((data)=> {
            console.info(`load content succeed with data ${JSON.stringify(data)}`)
        }).catch((error)=>{
            console.error(`load content failed with error ${JSON.stringify(error)}`)
        })
    }

    onWindowStageDestroy() {
        console.info("[Demo] BgTaskAbility onWindowStageDestroy")
    }

    onForeground() {
        console.info("[Demo] BgTaskAbility onForeground")
    }

    onBackground() {
        console.info("[Demo] BgTaskAbility onBackground")
    }
};

相关实例

基于后台任务管理,有以下相关实例可供参考:

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