我正在写一篇关于JobScheduler的教程，我发现了一个奇怪的行为。我要求在1秒钟内安排3个不同的工作（.setOverrideDeadline（1000））但是它们都被提交并运行了两次... 所以代码在这里：
public class MyApplication extends Application {
private static final int JOB_ID_HanlderThread = 100;
private static final int JOB_ID_ExecutorService = 200;
private static final int JOB_ID_AsyncTask = 300;
JobScheduler mJobScheduler;
ExecutorService myExecutorServiceForJobs=null;
private static MyApplication INSTANCE;
public static MyApplication getInstance(){
return INSTANCE;
}
/**
* Called when the application is starting, before any activity, service,
* or receiver objects (excluding content providers) have been created.
* Implementations should be as quick as possible (for example using
* lazy initialization of state) since the time spent in this function
* directly impacts the performance of starting the first activity,
* service, or receiver in a process.
* If you override this method, be sure to call super.onCreate().
*/
@Override
public void onCreate() {
Log.e("MyApplication", "*********************** onCreate *****************************");
super.onCreate();
//use only for the ExceutorService case
INSTANCE=this;
//instanciate your JobScheduler
mJobScheduler= (JobScheduler) getSystemService(JOB_SCHEDULER_SERVICE);
Log.e("MyApplication", "onCreate: JobScheduler instanciate");
//this first example use the HandlerThread (no need of executor service)
//---------------------------------------------------------------------
//define your JobServices here
JobInfo.Builder builder = new JobInfo.Builder(JOB_ID_HanlderThread,
new ComponentName( getPackageName(),
MyJobServiceUsingHandlerThread.class.getName() ) );
//begin in one second
builder.setOverrideDeadline(1000);
int returnedValue;
//the return value is failure(0) or success(1) not the JobId if success (Javadoc wrong)
returnedValue=mJobScheduler.schedule( builder.build() );
//launch it
if( returnedValue <= 0 ) {
//If something goes wrong (manage exception/error is better than logging them)
Log.e("MyApplication", "onCreate: JobScheduler launch the task failure");
}else{
//nothing goes wrong
Log.e("MyApplication", "onCreate: JobScheduler launch the task suceess JOB_ID_HanlderThread "+returnedValue);
}
//this second example use ExecutorService
//---------------------------------------
//then again define your Job and launch it
JobInfo.Builder builder1 = new JobInfo.Builder(JOB_ID_ExecutorService,
new ComponentName( getPackageName(),
MyJobServiceUsingExecutor.class.getName() ) );
//begin in one second
builder1.setOverrideDeadline(1000);
//launch it
returnedValue=mJobScheduler.schedule( builder1.build() );
if( returnedValue <= 0 ) {
//If something goes wrong (manage exception/error is better than logging them)
Log.e("MyApplication", "onCreate: JobScheduler launch the task failure");
}else{
//nothing goes wrong
Log.e("MyApplication", "onCreate: JobScheduler launch the task suceess JOB_ID_ExecutorService "+returnedValue);
}
//this third example use AsyncTask
//--------------------------------
//then again define your Job and launch it
JobInfo.Builder builder2 = new JobInfo.Builder(JOB_ID_AsyncTask,
new ComponentName( getPackageName(),
MyJobServiceUsingAsyncTask.class.getName() ) );
//begin in one second
builder2.setOverrideDeadline(1000);
//launch it
returnedValue=mJobScheduler.schedule( builder2.build() );
if( returnedValue <= 0 ) {
//If something goes wrong (manage exception/error is better than logging them)
Log.e("MyApplication", "onCreate: JobScheduler launch the task failure");
}else{
//nothing goes wrong
Log.e("MyApplication", "onCreate: JobScheduler launch the task suceess JOB_ID_AsyncTask "+returnedValue);
}
}
使用此代码我希望我的作业运行一次，但如果我查看我获得的日志：
10-20 06:45:13.118 13041-13041/? E/MyApplication: *********************** onCreate *****************************
10-20 06:45:13.122 13041-13041/? E/MyApplication: onCreate: JobScheduler instanciate
10-20 06:45:13.126 13041-13041/? E/MyApplication: onCreate: JobScheduler launch the task suceess JOB_ID_HanlderThread 1
10-20 06:45:13.127 13041-13041/? E/MyApplication: onCreate: JobScheduler launch the task suceess JOB_ID_ExecutorService 1
10-20 06:45:13.130 13041-13041/? E/MyApplication: onCreate: JobScheduler launch the task suceess JOB_ID_AsyncTask 1
10-20 06:45:13.559 13041-13041/? E/MyJobServiceHandler: onStartJob called <--------------------------------
10-20 06:45:13.572 13041-13041/? E/MyJobServiceExecutor: onStartJob called <--------------------------------
10-20 06:45:14.133 13041-13041/? E/MyJobServiceAsync: onStartJob called <--------------------------------
10-20 06:45:14.141 13041-13041/? E/MyJobServiceAsync: onStartJob called <--------------------------------
10-20 06:45:18.571 13041-13066/? E/MyHandler: The work is done in a separate thread called MyJobServiceUsingHandlerThread
10-20 06:45:18.573 13041-13041/? E/MyJobServiceHandler: onDestroy called, Looper is dead <******************************************
10-20 06:45:18.574 13041-13041/? E/MyJobServiceHandler: onStartJob called <--------------------------------
10-20 06:45:18.576 13041-13067/? E/MyRunnable: The work is done in a separate thread called MyJobServiceUsingExecutorService
10-20 06:45:18.577 13041-13041/? E/MyJobServiceExecutor: onDestroy called, executor service is dead <******************************************
10-20 06:45:18.577 13041-13041/? E/MyApplication: killMyExecutorServiceForJob called
10-20 06:45:18.577 13041-13041/? E/MyApplication: myExecutorServiceForJobs isShutDown
10-20 06:45:18.580 13041-13041/? E/MyJobServiceExecutor: onStartJob called <--------------------------------
10-20 06:45:19.145 13041-13070/? E/MyAsyncTask: The work is done in a separate thread called AsyncTask #1
10-20 06:45:19.145 13041-13041/? E/MyAsyncTask: The work is finished <******************************************
10-20 06:45:23.576 13041-13075/? E/MyHandler: The work is done in a separate thread called MyJobServiceUsingHandlerThread
10-20 06:45:23.577 13041-13041/? E/MyJobServiceHandler: onDestroy called, Looper is dead <******************************************
10-20 06:45:23.582 13041-13076/? E/MyRunnable: The work is done in a separate thread called MyJobServiceUsingExecutorService
10-20 06:45:23.584 13041-13041/? E/MyJobServiceExecutor: onDestroy called, executor service is dead <******************************************
10-20 06:45:23.584 13041-13041/? E/MyApplication: killMyExecutorServiceForJob called
10-20 06:45:23.584 13041-13041/? E/MyApplication: myExecutorServiceForJobs isShutDown
10-20 06:45:24.147 13041-13077/? E/MyAsyncTask: The work is done in a separate thread called AsyncTask #2
10-20 06:45:24.148 13041-13041/? E/MyAsyncTask: The work is finished <******************************************
我在教程中做的是使用HandlerThread运行一个Job，另一个使用ExecutorService运行，最后一个使用AsyncTask来解释如何在后台线程中完成工作。我展示了这种不同的技术，因为可能存在你想要在同一个线程（HandlerThread）中排队你的作业或管理一个Thread（ExecutorService）池或只使用非托管线程（AsyncTask）的用例。
我定义了Jobs并在MyApplication：onCreate方法中安排它们。 为了更深入地了解代码，我将它放在GitHub上：https://github.com/MathiasSeguy-Android2EE/JobSchedulerForGitHub
答案 0 :(得分：21)
谢谢你 - 我参与了JobScheduler。根据你的应用程序（谢谢！）我设法很容易地重复这个并找出错误的原因。
tl; dr，这是一个在教程应用程序之外不会经常发生的情况。要在教程中解决此问题，请将作业的截止日期增加到大于每个后台线程运行的时间。
正在发生的事情是你连续安排你的工作，而JobScheduler在安排工作时会立即运行它们。 然而，一秒钟之后（一秒钟是“真实”应用程序不会发生的部分）覆盖截止日期警报触发，而jobcheduler非常积极地决定任何截止日期已过期的作业需要再次运行（API合同规定“截止日期到期”胜过所有其他考虑因素），因此它将其置于待处理队列中。 一旦执行完作业，就会检查待处理队列，并且那里有一个工作，所以它就会运行。
因此，如果截止日期在作业运行时到期，则作业将激活2倍。确保截止日期在作业运行之前（导致作业运行）或之后（警报实际上不会使作业已经完成），并且一切都按预期运行。
我已经在Android N中解决了这个问题（不幸的是M已经发货），并添加了一个CTS测试以确保它保持不变。 感谢您引起我们的注意