实习笔记-20

App真正的入口

ActivityThread 中的main方法，一个应用程序对应一个ActivityThread对象，Zygote孵化出一个进程后，就会执行main方法

• 准备Looper和消息队列
• thread.attach()方法绑定到ActivityManagerService中

attach方法

private void attach(boolean system, long startSeq) {
    sCurrentActivityThread = this;
    mConfigurationController = new ConfigurationController(this);
    mSystemThread = system;
    if (!system) {
        android.ddm.DdmHandleAppName.setAppName("<pre-initialized>",
                                                UserHandle.myUserId());
        RuntimeInit.setApplicationObject(mAppThread.asBinder());
        final IActivityManager mgr = ActivityManager.getService();
        try {
            mgr.attachApplication(mAppThread, startSeq);
            //
        } catch (RemoteException ex) {
            throw ex.rethrowFromSystemServer();
        }
        // Watch for getting close to heap limit.
        BinderInternal.addGcWatcher(new Runnable() {
            @Override public void run() {
                if (!mSomeActivitiesChanged) {
                    return;
                }
                Runtime runtime = Runtime.getRuntime();
                long dalvikMax = runtime.maxMemory();
                long dalvikUsed = runtime.totalMemory() - runtime.freeMemory();
                if (dalvikUsed > ((3*dalvikMax)/4)) {
                    if (DEBUG_MEMORY_TRIM) Slog.d(TAG, "Dalvik max=" + (dalvikMax/1024)
                            + " total=" + (runtime.totalMemory()/1024)
                            + " used=" + (dalvikUsed/1024));
                    mSomeActivitiesChanged = false;
                    try {
                        ActivityTaskManager.getService().releaseSomeActivities(mAppThread);
                    } catch (RemoteException e) {
                        throw e.rethrowFromSystemServer();
                    }
                }
            }
        });
    } 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",
                UserHandle.myUserId());
        try {
            mInstrumentation = new Instrumentation();
            mInstrumentation.basicInit(this);
            ContextImpl context = ContextImpl.createAppContext(
                    this, getSystemContext().mPackageInfo);
            mInitialApplication = context.mPackageInfo.makeApplication(true, null);
            mInitialApplication.onCreate();
        } catch (Exception e) {
            throw new RuntimeException(
                    "Unable to instantiate Application():" + e.toString(), e);
        }
    }

    ViewRootImpl.ConfigChangedCallback configChangedCallback = (Configuration globalConfig) -> {
        synchronized (mResourcesManager) {
            // TODO (b/135719017): Temporary log for debugging IME service.
            if (Build.IS_DEBUGGABLE && mHasImeComponent) {
                Log.d(TAG, "ViewRootImpl.ConfigChangedCallback for IME, "
                        + "config=" + globalConfig);
            }

            // We need to apply this change to the resources immediately, because upon returning
            // the view hierarchy will be informed about it.
            if (mResourcesManager.applyConfigurationToResources(globalConfig,
                    null /* compat */,
                    mInitialApplication.getResources().getDisplayAdjustments())) {
                mConfigurationController.updateLocaleListFromAppContext(
                        mInitialApplication.getApplicationContext());

                // This actually changed the resources! Tell everyone about it.
                final Configuration updatedConfig =
                        mConfigurationController.updatePendingConfiguration(globalConfig);
                if (updatedConfig != null) {
                    sendMessage(H.CONFIGURATION_CHANGED, globalConfig);
                    mPendingConfiguration = updatedConfig;
                }
            }
        }
    };
    ViewRootImpl.addConfigCallback(configChangedCallback);
}