【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Data
        Data 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>() {
            @Override
            public 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() {
            @Override
            public 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
    @Override
    public 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();
    }