JetPack--WorkManager_综合

WorkManager是用于后台执行任务的工具，相比于Service、JobSchedule等，它拥有很低的能耗，但是它不是立即执行任务的，对于一些不需要及时完成的任务，使用WorkManager是一个很好的选择

WorkManager内部使用了数据库，所以能保证任务一定会执行。WorkManager的兼容性也很好，最低支持api14，api23以前，WorkManager内部是使用了JobSchedule，23以后使用的是AlarmManager+BroadCastReceiver

使用WorkManager需要添加gradle依赖：

implementation 'androidx.work:work-runtime:2.5.0'

1.使用WorkManager

定义Work类，继承Worker，doWork方法需要返回一个Result的结果，有成功、重试、失败：

package com.aruba.workmanager;import android.content.Context;
import android.util.Log;import androidx.annotation.NonNull;
import androidx.work.Worker;
import androidx.work.WorkerParameters;/*** Created by aruba on 2021/9/15.*/
public class MyWork extends Worker {private static final String TAG = MyWork.class.getSimpleName();public MyWork(@NonNull Context context, @NonNull WorkerParameters workerParams) {super(context, workerParams);}@NonNull@Overridepublic Result doWork() {Log.i(TAG,"doWork");return Result.success();}
}

在适当的地方，将任务入队：

//设置条件Constraints constraints = new Constraints.Builder()//NetworkType.CONNECTED:需要有网络//NetworkType.NOT_REQUIRED:不需要网络//NetworkType.NOT_ROAMING:非漫游网络//NetworkType.METERED:计费网络下执行(流量)//NetworkType.UNMETERED:不计费网络(wifi).setRequiredNetworkType(NetworkType.NOT_REQUIRED)
//                .setRequiresBatteryNotLow(true)//不在低电量
//                .setRequiresCharging(true)//充电时执行
//                .setRequiresStorageNotLow(true)//不在低存储空间
//                .setRequiresDeviceIdle(true)//不在待机 api23.build();//配置任务OneTimeWorkRequest workRequest = new OneTimeWorkRequest.Builder(MyWork.class).setConstraints(constraints)//设置延迟.setInitialDelay(5, TimeUnit.SECONDS).build();//任务入队WorkManager.getInstance(this).enqueue(workRequest);

2.指数退避策略

我们也可以为任务配置指数退避策略，当任务需要retry时，它会根据给定的退避时间指数增长，列如：退避时间为2，重试的时间间隔为：2，4，8...

//配置任务OneTimeWorkRequest workRequest = new OneTimeWorkRequest.Builder(MyWork.class).setConstraints(constraints)//设置延迟.setInitialDelay(5, TimeUnit.SECONDS)//指数退避策略.setBackoffCriteria(BackoffPolicy.LINEAR,2,TimeUnit.SECONDS).build();

3.为任务配置TAG

//配置任务OneTimeWorkRequest workRequest = new OneTimeWorkRequest.Builder(MyWork.class).setConstraints(constraints)//设置延迟.setInitialDelay(5, TimeUnit.SECONDS)//指数退避策略.setBackoffCriteria(BackoffPolicy.LINEAR,2,TimeUnit.SECONDS)//设置tag.addTag("work1").build();

4.监听任务状态

使用workManager对任务状态进行监听

//添加任务监听workManager.getWorkInfoByIdLiveData(workRequest.getId()).observe(this, new Observer<WorkInfo>() {@Overridepublic void onChanged(WorkInfo workInfo) {Log.i("WorkInfo", workInfo.toString());}});

5.取消任务

//取消任务workManager.cancelWorkById(workRequest.getId());

6.参数传递

参数传递分成两方面，一个是创建任务时传入参数，一个是执行任务时传递参数
使用Data在创建任务时传入参数：

//传入参数Data data = new Data.Builder().putString("createTask", "createTask").build();//配置任务OneTimeWorkRequest workRequest = new OneTimeWorkRequest.Builder(MyWork.class).setConstraints(constraints)//设置延迟.setInitialDelay(5, TimeUnit.SECONDS)//指数退避策略.setBackoffCriteria(BackoffPolicy.LINEAR, 2, TimeUnit.SECONDS)//设置tag.addTag("work1")//传入参数.setInputData(data).build();

在我们自定义的Work中，doWork方法内可以获取到创建时传递的参数，并且传递新的参数

@NonNull@Overridepublic Result doWork() {Log.i(TAG,"doWork");//获取参数String createTask = getInputData().getString("createTask");Log.i(TAG,"createTask");//传递新参数Data data = new Data.Builder().putString("doWork", "doWork complete").build();return Result.success(data);}

可以在监听任务状态时，获取完成任务的参数：

//添加任务监听workManager.getWorkInfoByIdLiveData(workRequest.getId()).observe(this, new Observer<WorkInfo>() {@Overridepublic void onChanged(WorkInfo workInfo) {Log.i("WorkInfo", workInfo.toString());if (workInfo != null && workInfo.getState() == WorkInfo.State.SUCCEEDED) {String doWork = workInfo.getOutputData().getString("doWork");Log.i("WorkInfo", doWork);}}});

7.周期性任务

使用PeriodicWorkRequest对象，并且指定的时间不能低于15分钟

//周期性任务if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.O) {PeriodicWorkRequest periodicWorkRequest = new PeriodicWorkRequest.Builder(MyWork.class, Duration.ofMinutes(15)).build();}

8.任务链与任务组合

任务也是可以链式执行的：

OneTimeWorkRequest aWork = new OneTimeWorkRequest.Builder(AWork.class).build();OneTimeWorkRequest bWork = new OneTimeWorkRequest.Builder(BWork.class).build();//先执行A再执行BworkManager.beginWith(aWork).then(bWork).enqueue();

任务组合，使用WorkContinuation的combine方法来组合WorkContinuation集合执行，可以使用then方法指定延后执行的任务：

OneTimeWorkRequest aWork = new OneTimeWorkRequest.Builder(AWork.class).build();OneTimeWorkRequest bWork = new OneTimeWorkRequest.Builder(BWork.class).build();OneTimeWorkRequest cWork = new OneTimeWorkRequest.Builder(CWork.class).build();OneTimeWorkRequest dWork = new OneTimeWorkRequest.Builder(DWork.class).build();OneTimeWorkRequest eWork = new OneTimeWorkRequest.Builder(EWork.class).build();//先A再BWorkContinuation workContinuation1 = workManager.beginWith(aWork).then(bWork);//先C再DWorkContinuation workContinuation2 = workManager.beginWith(cWork).then(dWork);List<WorkContinuation> workContinuations = new ArrayList<>();workContinuations.add(workContinuation1);workContinuations.add(workContinuation2);//最后执行EWorkContinuation.combine(workContinuations).then(eWork).enqueue();

JetPack--WorkManager