Question

我正在实施Firebase Jobdispatcher，触发时间指定在10到20秒之间。这是我安排工作的代码：

public static void scheduleCompatibleJob(Context context) {
    FirebaseJobDispatcher dispatcher = new FirebaseJobDispatcher(new GooglePlayDriver(context));
    Job myJob = dispatcher.newJobBuilder()
            .setService(DataTrackerJobService.class) // the JobService that will be called
            .setTag("api_trigger")
            .setRecurring(true)
            .setLifetime(Lifetime.FOREVER)
            .setTrigger(Trigger.executionWindow(10, 20)) // 10 to 20 seconds
            .setReplaceCurrent(true)
            .setRetryStrategy(RetryStrategy.DEFAULT_LINEAR)
            .setConstraints(Constraint.ON_ANY_NETWORK)
            .build();

    dispatcher.mustSchedule(myJob);
}

服务类：

public class DataTrackerJobService extends JobService {
@Override
public boolean onStartJob(final JobParameters job) {
    Log.e("start job", "started " + job);
    (new Handler()).postDelayed(new Runnable() {
        @Override
        public void run() {
            Log.e("handler", "run");
            jobFinished(job, true);
        }
    }, 2000);
    return true;
}

@Override
public boolean onStopJob(JobParameters job) {
    Log.e("stop job", "stopped " + job);
    return false;
}

}

作业调度程序正在运行，但logcat中的时间不正确。随着工作的每次重新安排，时间差距不断增加，并且从未在10到20秒之间。

06-07 11：19：16.429 26174-26174 / com.example.jobdispatcher E / start job：start com.firebase.jobdispatcher.JobInvocation@f4250de4 06-07 11：19：18.432 26174-26174 / com.example.jobdispatcher E / handler：run 06-07 11：20：16.436 26174-26174 / com.example.jobdispatcher E / start job：start com.firebase.jobdispatcher.JobInvocation@f16ceb31 06-07 11：20：18.438 26174-26174 / com.example.jobdispatcher E / handler：run 06-07 11：21：58.519 26174-26174 / com.example.jobdispatcher E / start job：start com.firebase.jobdispatcher.JobInvocation@f4c635cd 06-07 11：22：00.520 26174-26174 / com.example.jobdispatcher E / handler：run 06-07 11：23：40.602 26174-26174 / com.example.jobdispatcher E / start job：start com.firebase.jobdispatcher.JobInvocation@f15f8e29 06-07 11：23：42.605 26174-26174 / com.example.jobdispatcher E / handler：run 06-07 11：25：52.642 26174-26174 / com.example.jobdispatcher E / start job：start com.firebase.jobdispatcher.JobInvocation@f48c1045 06-07 11:25:54.644 26174-26174 / com.example.jobdispatcher E / handler：run 06-07 11：28：52.652 26174-26174 / com.example.jobdispatcher E / start job：start com.firebase.jobdispatcher.JobInvocation@f3b49821 06-07 11：28：54.655 26174-26174 / com.example.jobdispatcher E / handler：run 06-07 11：32：04.688 26174-26174 / com.example.jobdispatcher E / start job：start com.firebase.jobdispatcher.JobInvocation@e7f3c1bd 06-07 11：32：06.690 26174-26174 / com.example.jobdispatcher E / handler：run

请在logcat中查看时间。指导我在哪里出错，或者它应该只以这种方式工作？基本上我想实现它24小时的时间间隔，但我想知道这是否正常工作，然后在触发时间指定的时间加倍后，将调用作业。

Answer 1

如果您查看触发器类的来源，您会注意到您无法确定您的作业是否会在给定时间运行。

/**
 * Creates a new ExecutionWindow based on the provided time interval.
 *
 * @param windowStart The earliest time (in seconds) the job should be
 *                    considered eligible to run. Calculated from when the
 *                    job was scheduled (for new jobs) or last run (for
 *                    recurring jobs).
 * @param windowEnd   The latest time (in seconds) the job should be run in
 *                    an ideal world. Calculated in the same way as
 *                    {@code windowStart}.
 * @throws IllegalArgumentException if the provided parameters are too
 *                                  restrictive.
 */
public static JobTrigger.ExecutionWindowTrigger executionWindow(int windowStart, int windowEnd) {
    if (windowStart < 0) {
        throw new IllegalArgumentException("Window start can't be less than 0");
    } else if (windowEnd < windowStart) {
        throw new IllegalArgumentException("Window end can't be less than window start");
    }

    return new JobTrigger.ExecutionWindowTrigger(windowStart, windowEnd);
}

您还应注意，下一次重复性工作仅在前一次重复工作结束时才开始。因此，当您的工作耗时且昂贵时，下一个执行时间可能会出乎意料。对于耗时的工作，您应该扩展SimpleJobService。

为了创建重复的任务，我正在使用我的util方法创建一个合适的Trigger：

public class JobDispatcherUtils {
    public static JobTrigger periodicTrigger(int frequency, int tolerance) {
        return Trigger.executionWindow(frequency - tolerance, frequency);
    }
}

用法：

class DataTrackerJobService extends SimpleJobService {
    // ...
}

public static void scheduleCompatibleJob(Context context) {
    FirebaseJobDispatcher dispatcher = new FirebaseJobDispatcher(new GooglePlayDriver(context));
    Job myJob = dispatcher.newJobBuilder()
            .setService(DataTrackerJobService.class) // the JobService that will be called
            .setTag("api_trigger")
            .setRecurring(true)
            .setLifetime(Lifetime.FOREVER)
            .setTrigger(JobDispatcherUtils.periodicTrigger(20, 1)) // repeated every 20 seconds with 1 second of tollerance
            .setReplaceCurrent(true)
            .setRetryStrategy(RetryStrategy.DEFAULT_LINEAR)
            .setConstraints(Constraint.ON_ANY_NETWORK)
            .build();

    dispatcher.mustSchedule(myJob);
}

Firebase jobdispatcher未在指定窗口

1 个答案: