Android -- AMS總結

一、 AcitivityManager getRunningAppProcesses過程:

二、 AMS的Binder結構

三、 相關文件：
android.app.IActivityManager.java
android.app.ActivityManager.aidl
android.app.ActivityManager.java
android.app.ActivityManagerInternal.java
android.app.ActivityManagerNative.java
android.app.ActivityThread.java
com.android.server.am.ActivityManagerService.java
com.android.server.am.ActivityRecord.java
四、 分析

1. zygote entry :
   /**

   • The main entry point from zygote.
     */
     public static void main(String[] args) {
     new SystemServer().run();
     }

2. factory check ：
   public SystemServer() {
   // Check for factory test mode.
   private final int mFactoryTestMode = FactoryTest.getMode();
   }

3. 在systemserver主線程中設置系統屬性、加載android_servers庫、啓動各種java服務
   private void run() {
   // Prepare the main looper thread (this thread).
   Looper.prepareMainLooper();

   // Initialize native services.
   System.loadLibrary("android_servers");
   
   // Initialize the system context.
   createSystemContext();
   /*初始化系統上下文對象mSystemContext，並設置默認的主題,mSystemContext實際上是一個ContextImpl對象。
   *調用ActivityThread.systemMain()的時候，會調用ActivityThread.attach(true)，而在attach()裏面，
   *則創建了Application對象，並調用了Application.onCreate()。
   */
   private void createSystemContext() {
   ActivityThread activityThread = ActivityThread.systemMain();
   mSystemContext = activityThread.getSystemContext();
   mSystemContext.setTheme(android.R.style.Theme_DeviceDefault_Light_DarkActionBar);
   }
   
   // Create the system service manager.
   mSystemServiceManager = new SystemServiceManager(mSystemContext);
   LocalServices.addService(SystemServiceManager.class, mSystemServiceManager);
   
   // Start services.
   try {
       startBootstrapServices();
       startCoreServices();
       startOtherServices();
   } catch (Throwable ex) {
       Slog.e("System", "******************************************");
       Slog.e("System", "************ Failure starting system services", ex);
       throw ex;
   }
   
   // Loop forever.
   Looper.loop();
   throw new RuntimeException("Main thread loop unexpectedly exited");
   

   }

4. 啓動AMS
   /**
   * Starts the small tangle of critical services that are needed to get
   * the system off the ground. These services have complex mutual dependencies
   * which is why we initialize them all in one place here. Unless your service
   * is also entwined in these dependencies, it should be initialized in one of
   * the other functions.
   */
   private void startBootstrapServices() {
   // Wait for installd to finish starting up so that it has a chance to
   // create critical directories such as /data/user with the appropriate
   // permissions. We need this to complete before we initialize other services.
   Installer installer = mSystemServiceManager.startService(Installer.class);

   // Activity manager runs the show.
   private ActivityManagerService mActivityManagerService = mSystemServiceManager.startService(
           ActivityManagerService.Lifecycle.class).getService();
           {
               public static final class Lifecycle extends SystemService {
                   private final ActivityManagerService mService;
   
                   public Lifecycle(Context context) {
                       super(context);
                       mService = new ActivityManagerService(context);
                   }
   
                   @Override
                   public void onStart() {
                       mService.start();
                           private void start() {
                               Process.removeAllProcessGroups();
                               mProcessCpuThread.start();
   
                               mBatteryStatsService.publish(mContext);
                               mAppOpsService.publish(mContext);
                               Slog.d("AppOps", "AppOpsService published");
                               LocalServices.addService(ActivityManagerInternal.class, new LocalService());
                           }
   
                   }
   
                   public ActivityManagerService getService() {
                       return mService;
                   }
               }
           }
   mActivityManagerService.setSystemServiceManager(mSystemServiceManager);
   mActivityManagerService.setInstaller(installer);    
   
   // Now that the power manager has been started, let the activity manager
   // initialize power management features.
   mActivityManagerService.initPowerManagement();  
   
   // Set up the Application instance for the system process and get started.
   mActivityManagerService.setSystemProcess();
   

   }

   /**

   • Starts some essential services that are not tangled up in the bootstrap process.
     */
     private void startCoreServices() {
     mActivityManagerService.setUsageStatsManager(
     LocalServices.getService(UsageStatsManagerInternal.class));
     }

   /**

   • Starts a miscellaneous grab bag of stuff that has yet to be refactored

   • and organized.
     */
     private void startOtherServices() {

     Slog.i(TAG, "System Content Providers");
     mActivityManagerService.installSystemProviders();   
     
     Slog.i(TAG, "Init Watchdog");
     final Watchdog watchdog = Watchdog.getInstance();
     watchdog.init(context, mActivityManagerService);
     
     Slog.i(TAG, "Window Manager");
     wm = WindowManagerService.main(context, inputManager,
             mFactoryTestMode != FactoryTest.FACTORY_TEST_LOW_LEVEL,
             !mFirstBoot, mOnlyCore);
     ServiceManager.addService(Context.WINDOW_SERVICE, wm);
     ServiceManager.addService(Context.INPUT_SERVICE, inputManager);
     
     mActivityManagerService.setWindowManager(wm);
     
     mActivityManagerService.systemReady(new Runnable() {
         try {
             startSystemUi(context);
                 static final void startSystemUi(Context context) {
                     Intent intent = new Intent();
                     intent.setComponent(new ComponentName("com.android.systemui",
                                 "com.android.systemui.SystemUIService"));
                     //Slog.d(TAG, "Starting service: " + intent);
                     context.startServiceAsUser(intent, UserHandle.OWNER);
                 }
         } catch (Throwable e) {
             reportWtf("starting System UI", e);
         }
     }
     

     }