源码基于API26
在上一篇中，讲到由ActivityThread启动activity了
ActivityThread即我们平时提到的主线程，上一篇中AMS处理启动activity的task和record信息后通过binder跨进程到应用当前线程继续启动activity
现在看ActivityThread的scheduleLaunchActivity()
@Overridepublic final void scheduleLaunchActivity(Intent intent, IBinder token, int ident,ActivityInfo info, Configuration curConfig, Configuration overrideConfig,CompatibilityInfo compatInfo, String referrer, IVoiceInteractor voiceInteractor,int procState, Bundle state, PersistableBundle persistentState,List<ResultInfo> pendingResults, List<ReferrerIntent> pendingNewIntents,boolean notResumed, boolean isForward, ProfilerInfo profilerInfo) {//更新进程状态updateProcessState(procState, false);//创建ActivityClientRecord并赋值ActivityClientRecord r = new ActivityClientRecord();r.token = token;r.ident = ident;r.intent = intent;r.referrer = referrer;r.voiceInteractor = voiceInteractor;r.activityInfo = info;r.compatInfo = compatInfo;r.state = state;r.persistentState = persistentState;r.pendingResults = pendingResults;r.pendingIntents = pendingNewIntents;r.startsNotResumed = notResumed;r.isForward = isForward;r.profilerInfo = profilerInfo;r.overrideConfig = overrideConfig;updatePendingConfiguration(curConfig);//带着ActivityClientRecord由Handler启动ActivitysendMessage(H.LAUNCH_ACTIVITY, r);}复制代码接着看Handler
public void handleMessage(Message msg) {...switch (msg.what) {case LAUNCH_ACTIVITY: {Trace.traceBegin(Trace.TRACE_TAG_ACTIVITY_MANAGER, "activityStart");//handler传递过来的ActivityClientRecordfinal ActivityClientRecord r = (ActivityClientRecord) msg.obj;//赋值LoadedApkr.packageInfo = getPackageInfoNoCheck(r.activityInfo.applicationInfo, r.compatInfo);//继续启动activityhandleLaunchActivity(r, null, "LAUNCH_ACTIVITY");Trace.traceEnd(Trace.TRACE_TAG_ACTIVITY_MANAGER);} break;复制代码接着handleLaunchActivity()
private void handleLaunchActivity(ActivityClientRecord r, Intent customIntent, String reason) {//跳过后台执行gcunscheduleGcIdler();mSomeActivitiesChanged = true;if (r.profilerInfo != null) {mProfiler.setProfiler(r.profilerInfo);mProfiler.startProfiling();}// 确保执行最新的配置handleConfigurationChanged(null, null);if (localLOGV) Slog.v(TAG, "Handling launch of " + r);// 创建activity之前初始化WindowManagerGlobal,获取IWindowMangerWindowManagerGlobal.initialize();//启动activityActivity a = performLaunchActivity(r, customIntent);//activity不为nullif (a != null) {r.createdConfig = new Configuration(mConfiguration);reportSizeConfigurations(r);Bundle oldState = r.state;//恢复activityhandleResumeActivity(r.token, false, r.isForward,!r.activity.mFinished && !r.startsNotResumed, r.lastProcessedSeq, reason);if (!r.activity.mFinished && r.startsNotResumed) {performPauseActivityIfNeeded(r, reason);//pre-Honeycomb apps需要保存初始状态以便再次创建if (r.isPreHoneycomb()) {r.state = oldState;}}} else {//不管什么原因出错调用AMS销毁activitytry {ActivityManager.getService().finishActivity(r.token, Activity.RESULT_CANCELED, null,Activity.DONT_FINISH_TASK_WITH_ACTIVITY);} catch (RemoteException ex) {throw ex.rethrowFromSystemServer();}}
}复制代码接着performLaunchActivity()
private Activity performLaunchActivity(ActivityClientRecord r, Intent customIntent) {//LoadedApk检验ActivityInfo aInfo = r.activityInfo;if (r.packageInfo == null) {r.packageInfo = getPackageInfo(aInfo.applicationInfo, r.compatInfo,Context.CONTEXT_INCLUDE_CODE);}//component检验ComponentName component = r.intent.getComponent();if (component == null) {component = r.intent.resolveActivity(mInitialApplication.getPackageManager());r.intent.setComponent(component);}//原activity不为空可新建componentif (r.activityInfo.targetActivity != null) {component = new ComponentName(r.activityInfo.packageName,r.activityInfo.targetActivity);}//创建contextImplContextImpl appContext = createBaseContextForActivity(r);Activity activity = null;try {java.lang.ClassLoader cl = appContext.getClassLoader();//通过Instrumentation创建activity实例activity = mInstrumentation.newActivity(cl, component.getClassName(), r.intent);StrictMode.incrementExpectedActivityCount(activity.getClass());r.intent.setExtrasClassLoader(cl);r.intent.prepareToEnterProcess();if (r.state != null) {r.state.setClassLoader(cl);}} catch (Exception e) {if (!mInstrumentation.onException(activity, e)) {throw new RuntimeException("Unable to instantiate activity " + component+ ": " + e.toString(), e);}}try {//创建我们亲爱的applicationApplication app = r.packageInfo.makeApplication(false, mInstrumentation);if (localLOGV) Slog.v(TAG, "Performing launch of " + r);if (localLOGV) Slog.v(TAG, r + ": app=" + app+ ", appName=" + app.getPackageName()+ ", pkg=" + r.packageInfo.getPackageName()+ ", comp=" + r.intent.getComponent().toShortString()+ ", dir=" + r.packageInfo.getAppDir());if (activity != null) {//加载labelCharSequence title = r.activityInfo.loadLabel(appContext.getPackageManager());Configuration config = new Configuration(mCompatConfiguration);if (r.overrideConfig != null) {config.updateFrom(r.overrideConfig);}if (DEBUG_CONFIGURATION) Slog.v(TAG, "Launching activity "+ r.activityInfo.name + " with config " + config);Window window = null;if (r.mPendingRemoveWindow != null && r.mPreserveWindow) {window = r.mPendingRemoveWindow;r.mPendingRemoveWindow = null;r.mPendingRemoveWindowManager = null;}//context表示为activityappContext.setOuterContext(activity);//准备好了吗我们的activity来了activity.attach(appContext, this, getInstrumentation(), r.token,r.ident, app, r.intent, r.activityInfo, title, r.parent,r.embeddedID, r.lastNonConfigurationInstances, config,r.referrer, r.voiceInteractor, window, r.configCallback);if (customIntent != null) {activity.mIntent = customIntent;}r.lastNonConfigurationInstances = null;checkAndBlockForNetworkAccess();activity.mStartedActivity = false;int theme = r.activityInfo.getThemeResource();//设置主题if (theme != 0) {activity.setTheme(theme);}activity.mCalled = false;//activity已启动执行onCreate()了if (r.isPersistable()) {mInstrumentation.callActivityOnCreate(activity, r.state, r.persistentState);} else {mInstrumentation.callActivityOnCreate(activity, r.state);}if (!activity.mCalled) {throw new SuperNotCalledException("Activity " + r.intent.getComponent().toShortString() +" did not call through to super.onCreate()");}r.activity = activity;r.stopped = true;//没有关闭就要执行onStart()了if (!r.activity.mFinished) {activity.performStart();r.stopped = false;}if (!r.activity.mFinished) {//执行onRestoreInstanceState()if (r.isPersistable()) {if (r.state != null || r.persistentState != null) {mInstrumentation.callActivityOnRestoreInstanceState(activity, r.state,r.persistentState);}} else if (r.state != null) {mInstrumentation.callActivityOnRestoreInstanceState(activity, r.state);}}//没有finish()执行onPostCreate()if (!r.activity.mFinished) {activity.mCalled = false;if (r.isPersistable()) {mInstrumentation.callActivityOnPostCreate(activity, r.state,r.persistentState);} else {mInstrumentation.callActivityOnPostCreate(activity, r.state);}if (!activity.mCalled) {throw new SuperNotCalledException("Activity " + r.intent.getComponent().toShortString() +" did not call through to super.onPostCreate()");}}}r.paused = true;mActivities.put(r.token, r);} catch (SuperNotCalledException e) {throw e;} catch (Exception e) {if (!mInstrumentation.onException(activity, e)) {throw new RuntimeException("Unable to start activity " + component+ ": " + e.toString(), e);}}return activity;
}复制代码系不系上面这个方法有点长了，但是很显然是我们开发平时接触很近的方法了
再看看attach()
//主要是给我们activity赋一大堆值
final void attach(Context context, ActivityThread aThread,Instrumentation instr, IBinder token, int ident,Application application, Intent intent, ActivityInfo info,CharSequence title, Activity parent, String id,NonConfigurationInstances lastNonConfigurationInstances,Configuration config, String referrer, IVoiceInteractor voiceInteractor,Window window, ActivityConfigCallback activityConfigCallback) {attachBaseContext(context);mFragments.attachHost(null /*parent*/);//window创建并赋值mWindow = new PhoneWindow(this, window, activityConfigCallback);mWindow.setWindowControllerCallback(this);mWindow.setCallback(this);mWindow.setOnWindowDismissedCallback(this);mWindow.getLayoutInflater().setPrivateFactory(this);if (info.softInputMode != WindowManager.LayoutParams.SOFT_INPUT_STATE_UNSPECIFIED) {mWindow.setSoftInputMode(info.softInputMode);}if (info.uiOptions != 0) {mWindow.setUiOptions(info.uiOptions);}//看见没这就是uiThreadmUiThread = Thread.currentThread();//主线程为ActivityThreadmMainThread = aThread;//原来这货再这赋值的每一个activity都有这个监控类mInstrumentation = instr;mToken = token;mIdent = ident;mApplication = application;mIntent = intent;mReferrer = referrer;mComponent = intent.getComponent();mActivityInfo = info;mTitle = title;mParent = parent;mEmbeddedID = id;mLastNonConfigurationInstances = lastNonConfigurationInstances;if (voiceInteractor != null) {if (lastNonConfigurationInstances != null) {mVoiceInteractor = lastNonConfigurationInstances.voiceInteractor;} else {mVoiceInteractor = new VoiceInteractor(voiceInteractor, this, this,Looper.myLooper());}}mWindow.setWindowManager((WindowManager)context.getSystemService(Context.WINDOW_SERVICE),mToken, mComponent.flattenToString(),(info.flags & ActivityInfo.FLAG_HARDWARE_ACCELERATED) != 0);if (mParent != null) {mWindow.setContainer(mParent.getWindow());}mWindowManager = mWindow.getWindowManager();mCurrentConfig = config;mWindow.setColorMode(info.colorMode);
}复制代码还要问我activity启动了没有吗，我说没有
scheduleLaunchActivity()、handleLaunchActivity()、performLaunchActivity()
将activity的相关信息淋漓尽致的展现，没事多看看，我还没专研细致的方法呢。