android JobService相关源码分析

放入任务

1.1 getSystemService的过程
JobScheduler scheduler = (JobScheduler) this.getSystemService(Context.JOB_SCHEDULER_SERVICE);//这里的this是Activity
scheduler.schedule(jobInfo); //jobInfo持有JobService 的实现

frameworks/base/core/java/android/app/ContextImpl.java

public Object getSystemService(String name) {
return SystemServiceRegistry.getSystemService(this, name);
}

frameworks/base/core/java/android/app/SystemServiceRegistry.java

public Object getSystemService(String name) {
ServiceFetcher fetcher = SYSTEM_SERVICE_MAP.get(name);
return fetcher == null ? null : fetcher.getService(this);
}

public Object getService(ContextImpl ctx) {
service = createService(ctx); //如果cache里不存在，就调用createService来创建
}

registerService(JOB_SCHEDULER_SERVICE, new ServiceFetcher() {
public Object createService(ContextImpl ctx) {
IBinder b = ServiceManager.getService(JOB_SCHEDULER_SERVICE);  //b其实是mJobSchedulerStub
return new JobSchedulerImpl(IJobScheduler.Stub.asInterface(b)); //也就是说getSystemService获得的最终是JobSchedulerImpl
}
}

frameworks/base/core/java/android/app/JobSchedulerImpl.java

JobSchedulerImpl(IJobScheduler binder) {
mBinder = binder;
}

public int schedule(JobInfo job) {
try {
return mBinder.schedule(job); //也就是说通过JobScheduler调用schedule方法，其实就是调用mBinder的schedule方法
} catch (RemoteException e) {
return JobScheduler.RESULT_FAILURE;
}
}

1.2 ServiceManager.getService(JOB_SCHEDULER_SERVICE)过程解析

frameworks/base/core/java/android/os/ServiceManager.java

public static IBinder getService(String name) {
return getIServiceManager().getService(name); //如果cache中没有，就执行getIServiceManager().getService去获取
}

frameworks/base/services/core/java/com/android/server/job/JobSchedulerService.java

public void onStart() {
publishBinderService(Context.JOB_SCHEDULER_SERVICE, mJobSchedulerStub); //也就是说
//ServiceManager.getService(JOB_SCHEDULER_SERVICE)拿到的其实是mJobSchedulerStub                                                                                                                                                                              //拿到的其实是mJobSchedulerStub
}

frameworks/base/services/core/java/com/android/server/SystemService.java

protected final void publishBinderService(String name, IBinder service) {
publishBinderService(name, service, false);
}

protected final void publishBinderService(String name, IBinder service,boolean allowIsolated) {
ServiceManager.addService(name, service, allowIsolated);
}

frameworks/base/core/java/android/os/ServiceManager.java

try {
getIServiceManager().addService(name, service, allowIsolated);
} catch (RemoteException e) {
Log.e(TAG, "error in addService", e);
}

1.3 mJobSchedulerStub schedule方法

frameworks/base/services/core/java/com/android/server/job/JobSchedulerService.java

final class JobSchedulerStub extends IJobScheduler.Stub {
public int schedule(JobInfo job) throws RemoteException {
return JobSchedulerService.this.schedule(job, uid);  //调用JobSchedulerService的方法
}
}

public int schedule(JobInfo job, int uId) {
JobStatus jobStatus = new JobStatus(job, uId); //JobInfo 被封装成JobStatus
startTrackingJob(jobStatus);
}

private void startTrackingJob(JobStatus jobStatus) {
update = mJobs.add(jobStatus);
}

执行任务

2.1 JobService里面的onStartJob方法怎么被触发

frameworks/base/services/core/java/com/android/server/job/JobServiceContext.java
public class JobServiceContext extends IJobCallback.Stub implements ServiceConnection {
public void onServiceConnected(ComponentName name, IBinder service) {
this.service = IJobService.Stub.asInterface(service); //说明这个service就是JobService.java里面所提供的远端Service
mCallbackHandler.obtainMessage(MSG_SERVICE_BOUND).sendToTarget();
}
}

private class JobServiceHandler extends Handler {
public void handleMessage(Message message) {
switch (message.what) {
case MSG_SERVICE_BOUND:
handleServiceBoundH();
break;
}
}
private void handleServiceBoundH() {
service.startJob(mParams); //这里调用JobService.java里面的startJob
}
}

frameworks/base/core/java/android/app/job/JobService.java

IJobService mBinder = new IJobService.Stub() {   //IJobService.aidl的真正实现
@Override
public void startJob(JobParameters jobParams) {
ensureHandler();
Message m = Message.obtain(mHandler, MSG_EXECUTE_JOB, jobParams);
m.sendToTarget();
}

@Override
public void stopJob(JobParameters jobParams) {
ensureHandler();
Message m = Message.obtain(mHandler, MSG_STOP_JOB, jobParams);
m.sendToTarget();
}
};

        class JobHandler extends Handler {
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_EXECUTE_JOB:
try {
boolean workOngoing = JobService.this.onStartJob(params);
ackStartMessage(params, workOngoing);
} catch (Exception e) {
Log.e(TAG, "Error while executing job: " + params.getJobId());
throw new RuntimeException(e);
}
break;
}
}
}

    public abstract boolean onStartJob(JobParameters params); //abstract留给子类去覆盖，执行真正的动作 

    

    2.2 JobServiceContext 作为ServiceConnection怎么被使用

    frameworks/base/services/core/java/com/android/server/job/JobSchedulerService.java

public JobSchedulerService(Context context) {
mControllers.add(ConnectivityController.get(this)); //JobSchedulerService初始化时创建ConnectivityController
}

   

    frameworks/base/services/core/java/com/android/server/job/controllers/ConnectivityController.java

public static ConnectivityController get(JobSchedulerService jms) {
synchronized (sCreationLock) {
if (mSingleton == null) {
//创建ConnectivityController时会将参数JobSchedulerService作为mStateChangedListener而持有
mSingleton = new ConnectivityController(jms, jms.getContext());
}
return mSingleton;
}
}

    frameworks/base/services/core/java/com/android/server/job/controllers/ConnectivityController.java
public synchronized void onNetworkActive() { //网络可用时
mStateChangedListener.onRunJobNow(js);
}

    frameworks/base/services/core/java/com/android/server/job/JobSchedulerService.java

@Override
public void onRunJobNow(JobStatus jobStatus) {
mHandler.obtainMessage(MSG_JOB_EXPIRED, jobStatus).sendToTarget(); //JobHandler
}

private class JobHandler extends Handler {
@Override
public void handleMessage(Message message) {
maybeRunPendingJobsH();
}

private void maybeRunPendingJobsH() {
availableContext.executeRunnableJob(nextPending) //availableContext为JobServiceContext
}
}

    

    frameworks/base/services/core/java/com/android/server/job/JobServiceContext.java
boolean executeRunnableJob(JobStatus job) {
final Intent intent = new Intent().setComponent(job.getServiceComponent());//这里获得实现的JobService
//这里进行bindService的动作，而ServiceConnection就是JobServiceContext，这样上层实现的JobService就与JobServiceContext建立了联系
boolean binding = mContext.bindServiceAsUser(intent, this,Context.BIND_AUTO_CREATE | Context.BIND_NOT_FOREGROUND,new UserHandle(job.getUserId()));
}