Activity啟動流程【從Launcher點選圖示】和【在Activity中呼叫startActivity()】
阿新 • • 發佈：2019-01-26
從Launch程序啟動Application及Activity Android系統是基於Linux的，所以它的所有應用也是基於Linux的Init程序創建出來的， 首先Init程序啟動Zygote（受精卵）程序，然後再fork出其他程序（包括SystemServer），最後開啟各種應用程序 Zygote孵化的第一個程序是system_server程序，而且孵化的第一個App程序是Launcher，也就是桌面App。 當點選桌面App的時候，發起程序就是Launcher所在的程序，啟動遠端程序，利用Binder傳送訊息給system_server程序； 在system_server程序中啟動了N多服務，例如ActiivityManagerService，WindowManagerService等。 啟動程序的操作會先呼叫AMS.startProcessLocked方法，內部呼叫 Process.start(android.app.ActivityThread); 而後通過socket通訊告知Zygote程序fork子程序，即app程序。程序建立後將ActivityThread載入進去， 執行ActivityThread.main()方法，如下： 一、ActivityThread.main() 1.初始化主執行緒 Looper.prepareMainLooper(); 2.ActivityThread thread = new ActivityThread(); thread.attach(false); 3.判斷當前主執行緒的Handler是否為空 if (sMainThreadHandler == null) { sMainThreadHandler = thread.getHandler(); } 4.Looper.loop(); 5.attach(false) IActivityManager mgr = ActivityManagerNative.getDefault(); mgr.attachApplication(mAppThread);//mAppThread--ApplicationThread 二、ActivityManagerNative 6.getDefault()---gDefault.get() IBinder b = ServiceManager.getService("activity"); IActivityManager am = asInterface(b); return am; 7.getService("activity"); ServiceManager這裡是getService，ActivityManagerService.setSystemProcess()中有個ServiceManager.addService(); //ActivityManagerNative.ActivityManagerProxy 8.asInterface(b)---new ActivityManagerProxy(obj);//"回到6" mRemote = remote;//IBinder 9.mgr.attachApplication(mAppThread)在ActivityManagerNative中//將thread資訊AMS//"回到5" mRemote.transact(ATTACH_APPLICATION_TRANSACTION, data, reply, 0);//在system_server程序中，AMS會呼叫ActivityManagerNative.onTransact()//通過Binder程序間通訊進入到ActivityManagerService中 三、ActivityManagerService 10.attachApplication(mAppThread)在ActivityManagerService中//"回到5" attachApplicationLocked(thread, callingPid);//真正的邏輯部分 11.attachApplicationLocked(thread, callingPid)//thread--IApplicationThread thread.bindApplication(); mStackSupervisor.attachApplicationLocked(app)//app--ProcessRecord 四、ActivityThread 12.bindApplication(); sendMessage(H.BIND_APPLICATION, data); 13.handleBindApplication(data); final ContextImpl instrContext = ContextImpl.createAppContext(this, pi); final ClassLoader cl = instrContext.getClassLoader(); Instrumentation mInstrumentation = (Instrumentation) cl.loadClass(data.instrumentationName.getClassName()).newInstance(); Application app = data.info.makeApplication(data.restrictedBackupMode, null); mInstrumentation.callApplicationOnCreate(app);//---app.onCreate(); 五、LoadedApk 14.makeApplication(data.restrictedBackupMode, null); String appClass = mApplicationInfo.className; if (forceDefaultAppClass || (appClass == null)) appClass = "android.app.Application"; ContextImpl appContext = ContextImpl.createAppContext(mActivityThread, this); Application app = mActivityThread.mInstrumentation.newApplication(cl, appClass, appContext);//cl--getClassLoader() 六、Instrumentation---管家的角色 15.newApplication(cl, appClass, appContext); newApplication(cl.loadClass(className), context) Application app = (Application)clazz.newInstance();//反射建立，呼叫簡單粗暴,native方法 app.attach(context);//Application被建立後第一個呼叫的方法，目的是為了繫結Context 七、ActivityStackSupervisor 16.attachApplicationLocked(app)//"回到11"(***************************) realStartActivityLocked(hr, app, true, true) app.thread.scheduleLaunchActivity(); 八、ActivityThread 17.scheduleLaunchActivity();//--ApplicationThread sendMessage(H.LAUNCH_ACTIVITY, r);//傳送建立Activity的訊息 18.handleLaunchActivity(r, null, "LAUNCH_ACTIVITY");//處理訊息 Activity a = performLaunchActivity(r, customIntent);//建立並呼叫onCreate(),onStart() handleResumeActivity(r.token, false, r.isForward, !r.activity.mFinished && !r.startsNotResumed, r.lastProcessedSeq, reason);//呼叫onResume 19.performLaunchActivity(r, customIntent);//建立並呼叫onCreate(),onStart() java.lang.ClassLoader cl = r.packageInfo.getClassLoader(); Activity activity = mInstrumentation.newActivity(cl, component.getClassName(), r.intent);//建立Activity 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); if (r.isPersistable()) {//根據是否可持久化選擇callActivityOnCreate()方法。 mInstrumentation.callActivityOnCreate(activity, r.state, r.persistentState);//可獲得持久化資料; } else { mInstrumentation.callActivityOnCreate(activity, r.state); } if (!r.activity.mFinished) { activity.performStart();//呼叫onStart r.stopped = false; } if (!r.activity.mFinished) { if (r.isPersistable()) {//根據是否可持久化選擇callActivityOnRestoreInstanceState()方法。 if (r.state != null || r.persistentState != null) { mInstrumentation.callActivityOnRestoreInstanceState(activity, r.state, r.persistentState);//可獲得持久化資料; } } else if (r.state != null) { mInstrumentation.callActivityOnRestoreInstanceState(activity, r.state); } } if (!r.activity.mFinished) { activity.mCalled = false; if (r.isPersistable()) {//根據是否可持久化選擇callActivityOnCreate()方法。 mInstrumentation.callActivityOnPostCreate(activity, r.state, r.persistentState);//可獲得持久化資料; } else { mInstrumentation.callActivityOnPostCreate(activity, r.state); } ... } 九、Instrumentation 20.newActivity(cl, component.getClassName(), r.intent);//建立Activity (Activity)cl.loadClass(className).newInstance();//反射建立，呼叫native方法 21.callActivityOnCreate(); activity.performCreate(icicle);/activity.performCreate(icicle, persistentState); onCreate(icicle)//平時重寫的最多的;/onCreate(icicle, persistentState)//可獲得持久化資料; 22.callActivityOnRestoreInstanceState(); activity.performRestoreInstanceState(savedInstanceState);/activity.performRestoreInstanceState(savedInstanceState, persistentState); 23.callActivityOnPostCreate(); activity.onPostCreate(icicle);/activity.onPostCreate(icicle, persistentState); 十、Activity 24.performRestoreInstanceState(); onRestoreInstanceState(savedInstanceState);/onRestoreInstanceState(savedInstanceState, persistentState); 25.onPostCreate(); onPostCreate(savedInstanceState); if (!isChild()) { mTitleReady = true; onTitleChanged(getTitle(), getTitleColor()); } mCalled = true; 26.performStart();//呼叫onStart mInstrumentation.callActivityOnStart(this);---activity.onStart(); 十一、ActivityThread 27.handleResumeActivity();“回到18” r = performResumeActivity(token, clearHide, reason); r.activity.performResume(); 十二、Activity 28.performResume();//呼叫onResume mInstrumentation.callActivityOnResume(this);---activity.onResume();
在Activity中呼叫startActivity(); 一、Activity 1.startActivity() Instrumentation.ActivityResult ar = mInstrumentation.execStartActivity( this, mMainThread.getApplicationThread(), mToken, this, intent, requestCode, options); 二、Instrumentation 2.execStartActivity(); int result = ActivityManagerNative.getDefault().startActivity(whoThread, who.getBasePackageName(), intent, intent.resolveTypeIfNeeded(who.getContentResolver()), token, target != null ? target.mEmbeddedID : null, requestCode, 0, null, options); ActivityManagerProxy.startActivity(); BinderProxy.transact(); //Binder驅動將處理邏輯從Activity所在程序切換到ActivityManagerService所在程序 三、ActivityManagerService 3.startActivity(); startActivityAsUser(caller, callingPackage, intent, resolvedType, resultTo, resultWho, requestCode, startFlags, profilerInfo, options, UserHandle.getCallingUserId()); mStackSupervisor.startActivityMayWait(caller, -1, callingPackage, intent, resolvedType, null, null, resultTo, resultWho, requestCode, startFlags, profilerInfo, null, null, options, false, userId, null, null); 四、ActivityStackSupervisor 4.startActivityMayWait(); int res = startActivityLocked(caller, intent, resolvedType, aInfo, voiceSession, voiceInteractor, resultTo, resultWho, requestCode, callingPid, callingUid, callingPackage, realCallingPid, realCallingUid, startFlags, options, ignoreTargetSecurity, componentSpecified, null, container, inTask); int err = startActivityUncheckedLocked(r, sourceRecord, voiceSession, voiceInteractor, startFlags, true, options, inTask); targetStack.resumeTopActivityLocked(null, options);//啟動新的Activity之前，棧頂的Activity需要先onPause targetStack.startActivityLocked(r, newTask, doResume, keepCurTransition, options);//啟動Activity 五、ActivityStack 5.resumeTopActivityLocked(); result = resumeTopActivityInnerLocked(prev, options); 6.resumeTopActivityInnerLocked(); // We need to start pausing the current activity so the top one can be resumed... // 我們需要暫停當前的活動，這樣可以恢復最新的活動。 boolean dontWaitForPause = (next.info.flags& ActivityInfo.FLAG_RESUME_WHILE_PAUSING) != 0; boolean pausing = mStackSupervisor.pauseBackStacks(userLeaving, true, dontWaitForPause);//暫停所有的Activity if (mResumedActivity != null) { ... pausing |= startPausingLocked(userLeaving, false, true, dontWaitForPause);//暫停當前的Activity } 5.startActivityLocked();//啟動Activity task.addActivityToTop(r);//將Activity新增至棧頂 task.setFrontOfTask();//設定Activity為棧內前天 ensureActivitiesVisibleLocked(null, 0);//確保Activity使用者可見，啟動Activity 6.ensureActivitiesVisibleLocked(null, 0);//啟動Activity mStackSupervisor.startSpecificActivityLocked(r, noStackActivityResumed, false); 六、ActivityStackSupervisor 7.startSpecificActivityLocked(); realStartActivityLocked(r, app, andResume, checkConfig); app.thread.scheduleLaunchActivity();//接下來同“從Launch程序啟動Application及Activity---七-16 加***處”
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