返回 Binder 對象：

IBinder iBinder = ServiceManager.getService(Context.NOTIFICATION_SERVICE)

返回 Binder 接口對象（即Service接口）：

• 一般獲取方式：

INotificationManager sINM = INotificationManager.Stub.asInterface(ServiceManager.getService(Context.NOTIFICATION_SERVICE));

• 有些 XxxManager 中有 getService() 方法，也可以獲取到 Binder 接口對象：
• android.app.ActivityManager

    public static IActivityManager getService() {
        return (IActivityManager)IActivityManagerSingleton.get();
    }

返回 封裝的 XxxManager 對象：

ActivityManager mActivityManager = (ActivityManager) mContext.getSystemService(Context.ACTIVITY_SERVICE);

StorageManager mStorageManager = mContext.getSystemService(StorageManager.class);

• 有些通過 XxxManager from( ) 的方式：

StorageManager storageManager = StorageManager.from(mContext);

public static StorageManager from(Context context) {
    return context.getSystemService(StorageManager.class);
}