ActivityManagerService和ActivityTaskManagerService详解—Android 12（二）

详解—Android 12（二）"/>

ActivityManagerService和ActivityTaskManagerService详解—Android 12（二）

接上一篇博客ActivityManagerService和ActivityTaskManagerService启动详解—Android 12（一），介绍了SystemServer.starBootstrapServices()中启动AMS和ATMS所做的工作，这一节介绍在SystemServer.startCoreServices()中关于AMS和ATMS设置UsageStateManagerInternal服务来跟踪application使用状态的业务。

目录

1. AMS和ATMS设置UsageStateManagerInternal服务

1.1 AMS.setUsageStatsManager() 

1.2 ATMS.setUsageStatsManager() 

1.3 UsageStatsManagerInternal 

1.4 UsageStatsService

1.4.1 UsageStatsService.onStart()

1.4.2 UsageStatsService的内部类BinderService

1.4.3 UsageStatsService的内部类LocalServicce 

2. 创建系统服务的步骤

1. AMS和ATMS设置UsageStateManagerInternal服务

// /frameworks/base/services/java/com/android/server/SystemServer.java
public final class SystemServer implements Dumpable {private void startCoreServices(@NonNull TimingsTraceAndSlog t) {// Tracks application usage stats.t.traceBegin("StartUsageService");mSystemServiceManager.startService(UsageStatsService.class);mActivityManagerService.setUsageStatsManager(LocalServices.getService(UsageStatsManagerInternal.class));t.traceEnd();}   
} 

1.1 AMS.setUsageStatsManager() 

// /frameworks/base/services/core/java/com/android/server/am/ActivityManagerService.java
public class ActivityManagerService extends IActivityManager.Stubimplements Watchdog.Monitor, BatteryStatsImpl.BatteryCallback, ActivityManagerGlobalLock {   public void setUsageStatsManager(@NonNull UsageStatsManagerInternal usageStatsManager)             {mUsageStatsService = usageStatsManager;mActivityTaskManager.setUsageStatsManager(usageStatsManager);}
}

1.2 ATMS.setUsageStatsManager() 

// /frameworks/base/services/core/java/com/android/server/wm/ActivityTaskManagerService.java
public class ActivityTaskManagerService extends IActivityTaskManager.Stub {public void setUsageStatsManager(UsageStatsManagerInternal usageStatsManager) {synchronized (mGlobalLock) {mUsageStatsInternal = usageStatsManager;}}
}

1.3 UsageStatsManagerInternal 

它是UsageStatsService的本地系统服务接口，源码参考地址：UsageStatsManagerInternal.java - OpenGrok cross reference for /frameworks/base/services/core/java/android/app/usage/UsageStatsManagerInternal.java

// /frameworks/base/services/core/java/android/app/usage/UsageStatsManagerInternal.java
public abstract class UsageStatsManagerInternal {public abstract void reportEvent(ComponentName component, @UserIdInt int userId, int eventType,int instanceId, ComponentName taskRoot);public abstract void reportEvent(String packageName, @UserIdInt int userId, int eventType);public abstract void reportConfigurationChange(Configuration config, @UserIdInt int userId);public abstract void reportContentProviderUsage(String name, String pkgName,@UserIdInt int userId);public abstract void reportLocusUpdate(@NonNull ComponentName activity, @UserIdInt int userId,@Nullable LocusId locusId, @NonNull IBinder appToken);/*** Prepares the UsageStatsService for shutdown.*/public abstract void prepareShutdown();/*** When the device power button is long pressed for 3.5 seconds, prepareForPossibleShutdown()* is called.*/public abstract void prepareForPossibleShutdown();public abstract List<UsageStats> queryUsageStatsForUser(@UserIdInt int userId, int interval,long beginTime, long endTime, boolean obfuscateInstantApps);public abstract void reportAppJobState(String packageName, @UserIdInt int userId,int numDeferredJobs, long timeSinceLastJobRun);public abstract void reportSyncScheduled(String packageName, @UserIdInt int userId,boolean exempted);public abstract AppUsageLimitData getAppUsageLimit(String packageName, UserHandle user);public interface UsageEventListener {/** Callback to inform listeners of a new usage event. */void onUsageEvent(@UserIdInt int userId, @NonNull UsageEvents.Event event);}public abstract void registerListener(@NonNull UsageEventListener listener);public abstract void unregisterListener(@NonNull UsageEventListener listener);
}

该本地服务是SSM.startService()时在UsageStatsService.onStart()中注册到LocalServices中的。

1.4 UsageStatsService

该系统服务主要负责收集、聚合和持久化application使用数据。这些数据可以被AppOps授权的应用查询。它的持久化数据保存路径为data/system/usagestats。

1.4.1 UsageStatsService.onStart()

•  把UsageStatsManagerInternal服务和对应的实例注册LocalServices中；
• 把BinderServce以name=usagestats注册到servicemanager中。

// /frameworks/base/services/usage/java/com/android/server/usage/UsageStatsService.java
public class UsageStatsService extends SystemService implementsUserUsageStatsService.StatsUpdatedListener {public UsageStatsService(Context context) {this(context, new Injector());}@Overridepublic void onStart() {mAppOps = (AppOpsManager) getContext().getSystemService(Context.APP_OPS_SERVICE);mUserManager = (UserManager) getContext().getSystemService(Context.USER_SERVICE);mPackageManager = getContext().getPackageManager();mPackageManagerInternal = LocalServices.getService(PackageManagerInternal.class);mHandler = new H(BackgroundThread.get().getLooper());...//把UsageStasManagerInternal服务注册到LocalServices中publishLocalService(UsageStatsManagerInternal.class, new LocalService());publishLocalService(AppStandbyInternal.class, mAppStandby);//把UsageStatsService以name=usagestats注册到servicemanager中publishBinderServices();}void publishBinderServices() {publishBinderService(Context.USAGE_STATS_SERVICE, new BinderService());}
}

1.4.2 UsageStatsService的内部类BinderService

// /frameworks/base/services/usage/java/com/android/server/usage/UsageStatsService.java
public class UsageStatsService extends SystemService implementsUserUsageStatsService.StatsUpdatedListener {@Overridepublic void onStart() {...//把UsageStatsService以name=usagestats注册到servicemanager中publishBinderServices();}void publishBinderServices() {publishBinderService(Context.USAGE_STATS_SERVICE, new BinderService());}//由于UsageStatsService继承了SystemService, 所以内部类BinderService extends//IUsageStatsManager.Stub, 作为服务端，这样同样实现了使用AIDL与其他app交互。private final class BinderService extends IUsageStatsManager.Stub {private boolean hasPermissions(String callingPackage, String... permissions) {final int callingUid = Binder.getCallingUid();if (callingUid == Process.SYSTEM_UID) {// Caller is the system, so proceed.return true;}boolean hasPermissions = true;final Context context = getContext();for (int i = 0; i < permissions.length; i++) {hasPermissions = hasPermissions && (context.checkCallingPermission(permissions[i])== PackageManager.PERMISSION_GRANTED);}return hasPermissions;}@Overridepublic ParceledListSlice<UsageStats> queryUsageStats(int bucketType, long beginTime,long endTime, String callingPackage, int userId) {if (!hasPermission(callingPackage)) {return null;}    ...}}    
}

1.4.3 UsageStatsService的内部类LocalServicce 

该LocalServicce继承了UsageStatsManagerInternal,该本地服务主要供AMS使用。AMS会持有am锁来调用LocalService中的方法，所以在这些方法中不应有IO操作或者其他耗时任务。

// /frameworks/base/services/usage/java/com/android/server/usage/UsageStatsService.java
public class UsageStatsService extends SystemService implementsUserUsageStatsService.StatsUpdatedListener {@Overridepublic void onStart() {...//把UsageStasManagerInternal服务注册到LocalServices中publishLocalService(UsageStatsManagerInternal.class, new LocalService());}//该LocalServicce继承了UsageStatsManagerInternal,该本地服务主要供AMS使用,//AMS会持有am锁来调用LocalService中的方法,所以在这些方法中不应有IO操作或者其他耗时任务private final class LocalService extends UsageStatsManagerInternal {@Overridepublic void reportEvent(ComponentName component, int userId, int eventType,int instanceId, ComponentName taskRoot) {if (component == null) {Slog.w(TAG, "Event reported without a component name");return;}Event event = new Event(eventType, SystemClock.elapsedRealtime());event.mPackage = component.getPackageName();event.mClass = component.getClassName();event.mInstanceId = instanceId;if (taskRoot == null) {event.mTaskRootPackage = null;event.mTaskRootClass = null;} else {event.mTaskRootPackage = taskRoot.getPackageName();event.mTaskRootClass = taskRoot.getClassName();}reportEventOrAddToQueue(userId, event);}@Overridepublic void reportEvent(String packageName, int userId, int eventType) {if (packageName == null) {Slog.w(TAG, "Event reported without a package name, eventType:" + eventType);return;}Event event = new Event(eventType, SystemClock.elapsedRealtime());event.mPackage = packageName;reportEventOrAddToQueue(userId, event);}...}
}

2. 创建系统服务的步骤

UsageStatsService的代码让我发现创建系统服务的另一种形式，创建需要和application等其他进程通过AIDL通信的步骤：

(1). 创建新的系统服务类直接继承SystemService，重写onStart()。

(2). 创建内部类，继承ICustomizeManager.stub

(3). 在onStart()中调用publishBinderService(String name, IBinder service)注册到servicemanager中。      

//第一步
public CustomizeSystemService extends SystemService {@Overridepublic void onStart() {//第三步：把CustomizeBinderService注册到servicemanager中publishBinderService(Context.CUSTOMIZE_SERVICE, new CustomizeBinderService());        }//第二步private final class CustomizeBinderService extends ICustomizeManager.Stub {//重写AIDL文件中的方法}
}

使用最多的形式参考 请参考Framework层添加SystemService和Manager的超详细步骤