【JetPack】WorkManager笔记

WorkManager简介：
WorkManager 是 Android Jetpack 库中的一个重要组件。它用于处理那些需要在后台可靠执行的任务，这些任务可以是一次性的，也可以是周期性的，甚至是需要满足特定条件才执行的任务。例如，它可以用于在后台上传文件、下载更新、清理缓存等操作。
与传统的后台处理方式相比，WorkManager 具有很多优势。它可以根据设备的状态（如网络可用性、电量等）智能地调度任务，确保任务能够在合适的时机执行。即使应用程序进程被杀死，它依然能够保证任务的执行，这对于一些重要的后台任务来说是非常关键的。

		// 创建DataData data = new Data.Builder().putString("inputData", "Jay").build();

		// 创建触发条件 (触发条件满足，不会立刻执行）Constraints constraints = new Constraints.Builder().setRequiredNetworkType(NetworkType.NOT_REQUIRED).build();

		// 创建一次性执行的任务OneTimeWorkRequest workRequest1 = null;if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {workRequest1 = new OneTimeWorkRequest.Builder(MyWork.class)// 设置触发条件.setConstraints(constraints)// 设置延迟执行.setInitialDelay(5, TimeUnit.SECONDS)// 指数退避策略，如果返回结果是retry，那么按线性2s，重复执行，大概就是2，4，8.setBackoffCriteria(BackoffPolicy.LINEAR, Duration.ofSeconds(2))// 设置标签.addTag("workRequest1")// 参数传递.setInputData(data).build();}

 		// 任务提交给系统WorkManager workManager = WorkManager.getInstance(this);// 将任务加入workManager队列workManager.enqueue(workRequest1);

 		// 观察任务状态workManager.getWorkInfoByIdLiveData(workRequest1.getId()).observe(this, new Observer<WorkInfo>() {@Overridepublic void onChanged(WorkInfo workInfo) {Log.d("test", workInfo.toString());if (workInfo != null) {String outString = workInfo.getOutputData().getString("key");Log.d("test", "outString = " + outString);}}});

		// 取消任务OneTimeWorkRequest finalWorkRequest = workRequest1;new Timer().schedule(new TimerTask() {@Overridepublic void run() {workManager.cancelWorkById(finalWorkRequest.getId());}}, 2000);

 		// 创建周期性任务 (周期不可少于15min）if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.O) {PeriodicWorkRequest periodicWorkRequest = new PeriodicWorkRequest.Builder(MyWork.class, Duration.ofMinutes(15)).build();workManager.enqueue(periodicWorkRequest);}

MyWork继承Worker类，在满足条件时执行Work

public class MyWork extends Worker {public MyWork(@NonNull Context context, @NonNull WorkerParameters workerParams) {super(context, workerParams);}@NonNull@Overridepublic Result doWork() {
//        SystemClock.sleep(2000);String inputData = getInputData().getString("inputData");Log.d("test","MyWork doWork " + inputData);// 将参数传递回去Data data = new Data.Builder().putString("key", "执行成功").build();return Result.success(data);}
}

任务组合

public void addWork(View view) {OneTimeWorkRequest workRequest1 = new OneTimeWorkRequest.Builder(AWorker.class).build();OneTimeWorkRequest workRequest2 = new OneTimeWorkRequest.Builder(BWorker.class).build();OneTimeWorkRequest workRequest3 = new OneTimeWorkRequest.Builder(CWorker.class).build();OneTimeWorkRequest workRequest4 = new OneTimeWorkRequest.Builder(DWorker.class).build();OneTimeWorkRequest workRequest5 = new OneTimeWorkRequest.Builder(EWorker.class).build();// 任务组合WorkContinuation workContinuation1 = WorkManager.getInstance(this).beginWith(workRequest3).then(workRequest4);WorkContinuation workContinuation2 = WorkManager.getInstance(this).beginWith(workRequest1).then(workRequest2);List<WorkContinuation> list = new ArrayList<>();list.add(workContinuation1);list.add(workContinuation2);WorkContinuation.combine(list).then(workRequest5).enqueue();}