android JobService相关源码分析

1. 放入任务
   1.1 getSystemService的过程
   

   JobScheduler scheduler = (JobScheduler) this.getSystemService(Context.JOB_SCHEDULER_SERVICE);//这里的this是Activityscheduler.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);}

   
   

2. 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()));     }