我使用以下代码来安排每15分钟执行一次后台作业。
WorkManager workManager = WorkManager.getInstance();
PeriodicWorkRequest ulpBackup;
ulpBackup = new PeriodicWorkRequest
.Builder(Ulp.class, 15, TimeUnit.MINUTES)
.addTag(activity.getString(R.string.job_tag))
.build();
workManager.enqueue(ulpBackup);
这是UlpBackup.class
public class UlpBackup extends Worker {
private Integer responseCounter = 0;
public UlpBackup() {}
@NonNull
@Override
public Result doWork() {
Log.d(logTag, "Starting periodic backup job";
final CountDownLatch countDownLatch = new CountDownLatch(1);
/** Read from local database and upload to firestore **/
localdb.setAPIListener(new APIListener() {
@Override
public void OnSuccess() {
responseCounter++;
if (responseCounter == 5) {
countDownLatch.countDown();
}
}
@Override
public void OnFailure() {
responseCounter++;
if (responseCounter == 5) {
countDownLatch.countDown();
}
}
});
localdb.sync();
try {
countDownLatch.await(300, TimeUnit.SECONDS);
} catch (Exception exception) {
Log.e(logTag, "Error in user list backup job " + exception.getMessage());
return Result.FAILURE;
}
Log.e(logTag, "Ulp backup completed");
return Result.SUCCESS;
}
上面的代码工作正常,工作大致每15分钟发生一次。我唯一不理解的是每次工作多次执行时,有人可以解释为什么以及如何避免它?
从日志中:
09-15 23:33:37.514 8190-8410: Starting periodic backup job
09-15 23:33:37.520 8190-8414: Starting periodic backup job
09-15 23:33:37.561 8190-8412: Starting periodic backup job
09-15 23:33:37.568 8190-8413: Starting periodic backup job
...
...
09-15 23:33:38.183 8190-8414: Ulp backup completed
09-15 23:33:39.164 8190-8412: Ulp backup completed
09-15 23:33:39.580 8190-8413: Ulp backup completed
09-15 23:38:37.517 8190-8410: Ulp backup completed
你可以使用以下方法:enqueueUniquePeriodicWork()
,并实现如下:
WorkManager.getInstance().enqueueUniquePeriodicWork("YOUR_TAG", ExistingPeriodicWorkPolicy.KEEP, workRequest);
请注意第二个参数是关键。枚举可以是KEEP
或REPLACE
我想我回答这个问题的时间已经很晚了,你也可能已经调整过了..但我还是试着帮助..
我唯一不理解的是,每次工作多次执行时,
can someone explain
为什么以及如何避免它?
如果我说的话,每个人都会感到震惊:
哦,我的上帝..如果我正在做任何数据库操作那将导致
data-loss
.. !! ??
是的,它导致数据丢失很多次..
Android和开发人员有什么工作吗?
是的,更喜欢使用IntentService
。
IntentService
有什么特别之处?
如果intentservice
已经运行,即使thousands
有时被调用...那么在那种情况下...所有的调用都保存在queue
由android和处理one by one
和one after another
后一个是finished
然后只有另一个等待awakes
和开始执行它
希望能帮助到你。