anroid SystemServer启动中调用ActivityManagerService.main(int factoryTest)流程

[1]android系统启动第一次调用ActivityManagerService中main方法设置系统上下环境,

并保存在 mContext成员变量中

SystemServer启动后会调用ActivityManagerService中的main函数:

frameworks/base/services/java/com/android/server/am/ActivityManagerService.java

    publicstatic final Context main(int factoryTest){

        AThread thr=new AThread();//new了一个ActivityManagerService类保存在成员变量mService中

        thr.start();

 

        synchronized(thr){

            while(thr.mService== null){

                try{

                    thr.wait();

                }catch(InterruptedException e){

                }

            }

        }

 

        ActivityManagerService m= thr.mService;//将AThread中的成员变量mService给ActivityManagerServer成员变量m

        mSelf = m; //将ActivityManagerServer对象m附值给成员变量mSelf

        ActivityThread at= ActivityThread.systemMain();//启动一个systemMain ActivityThread

        mSystemThread= at;

        Context context= at.getSystemContext(); //将systemMain的上下环境给context变量,之后再传给ActivityManagerServer成员变量mContext

        m.mContext= context; //附值给mContext

        m.mFactoryTest= factoryTest;

        m.mMainStack=new ActivityStack(m, context,true);

 

        m.mBatteryStatsService.publish(context);

        m.mUsageStatsService.publish(context);

 

        synchronized(thr){

            thr.mReady=true;

            thr.notifyAll();

        }

 

        m.startRunning(null, null, null, null);

 

        return context;

    }

 

[2] ActivityThread.systemMain:

framework/base/core/java/android/app/ActivityThread.java

publicstatic final ActivityThread systemMain(){

    ActivityThread thread= new ActivityThread();//调用一个空的构造函数,生成对象,系统线程,此线程在Home Activity创建之前生成.

    thread.attach(true);//

    return thread;

}

[3]执行attach初始化context

 

    private finalvoid attach(boolean system){

        sThreadLocal.set(this);

        mSystemThread= system;

        if(!system){

            ViewRoot.addFirstDrawHandler(new Runnable(){

                publicvoid run(){

                    ensureJitEnabled();

                }

            });

            android.ddm.DdmHandleAppName.setAppName("<pre-initialized>");

            RuntimeInit.setApplicationObject(mAppThread.asBinder());

            IActivityManager mgr= ActivityManagerNative.getDefault();

            try{

                mgr.attachApplication(mAppThread);

            }catch(RemoteException ex){

            }

        }else{

            // Don't set application object here -- if the system crashes,

            // we can't display an alert, we just want to die die die.

            android.ddm.DdmHandleAppName.setAppName("system_process");

            try{

                mInstrumentation =new Instrumentation();

                ContextImpl context =new ContextImpl();

                context.init(getSystemContext().mPackageInfo, null, this);

                Application app = Instrumentation.newApplication(Application.class, context);

                mAllApplications.add(app);

                mInitialApplication = app;

                app.onCreate();//启动app

            }catch(Exception e){

                thrownew RuntimeException(

                       "Unable to instantiate Application():"+ e.toString(), e);

            }

        }

 

        ViewRoot.addConfigCallback(new ComponentCallbacks(){

            publicvoid onConfigurationChanged(Configuration newConfig){

                synchronized (mPackages){

                    // We need to apply this change to the resources

                    // immediately, because upon returning the view

                    // hierarchy will be informed about it.

                    if(applyConfigurationToResourcesLocked(newConfig)){

                       // This actually changed the resources! Tell

                       // everyone about it.

                       if(mPendingConfiguration== null||

                               mPendingConfiguration.isOtherSeqNewer(newConfig)){

                           mPendingConfiguration = newConfig;

 

                           queueOrSendMessage(H.CONFIGURATION_CHANGED, newConfig);

                       }

                    }

                }

            }

            publicvoid onLowMemory(){

            }

        });

    }

 

[4]接着看getSystemContext:

    public ContextImpl getSystemContext(){

        synchronized(this){

            if(mSystemContext== null){

                ContextImpl context =ContextImpl.createSystemContext(this);

//调用ContextImpl静态方法,生成当前对象的上下环境对象

                LoadedApk info = new LoadedApk(this, "android", context, null);

                context.init(info, null,this);

                context.getResources().updateConfiguration(

                       getConfiguration(), getDisplayMetricsLocked(false));

                mSystemContext = context;

                //Slog.i(TAG, "Created system resources " + context.getResources()

                //        + ": " + context.getResources().getConfiguration());

            }

        }

        return mSystemContext;

    }