Android 11（platfrom 30）APP啟動流程（含Activity）核心點記錄-有解無憂

前言：邊分析，邊記錄不斷更新

場景一、從桌面點擊APP圖示進行啟動

涉及到的核心行程：

step 1：

決議AndroidManifest檔案組裝Intent物件

--> Activity --- startActivity

--> Activity --- startActivityForResult

--> Instrumentation --- execStartActivity

--- ActivityTaskManager.getService().startActivity 此處是通過Binder跨行程通信去呼叫系統進程SystemService 的ActivityMangerService 以下簡稱AMS

--> AMS --- startActivity

--> ActivityTaskManagerService --- startActivity 1043行

--> ActivityTaskManagerService --- startActivityAsUser 1068行

--> ActivityTaskManagerService --- startActivityAsUser 1077行

--- getActivityStartController().obtainStarter 這里得到了一個 ActivityStarter物件

--> ActivityStarter --- execute 628行

--> ActivityStarter --- executeRequest 835行 --- 1186行 startActivityUnchecked

--> ActivityStarter --- startActivityUnchecked 1512行

--> ActivityStarter --- startActivityInner 1587行

--> ActivityStarter --- startActivityInner 1587行 1731行

--> RootWindowContainer --- resumeFocusedStacksTopActivities 2285行

--> RootWindowContainer --- resumeFocusedStacksTopActivities 2289行 2299行

--> ActivityStack --- resumeTopActivityUncheckedLocked 1501行

--> ActivityStack --- resumeTopActivityInnerLocked 1532行 1961行

--> ActivityStackSupervisor --- startSpecificActivity 1961行

這里是核心代碼是step 2 a 和 step 2 b的分支判斷的地方

void startSpecificActivity(ActivityRecord r, boolean andResume, boolean checkConfig) {
        // Is this activity's application already running?
        final WindowProcessController wpc =
                mService.getProcessController(r.processName, r.info.applicationInfo.uid);

        boolean knownToBeDead = false;
        if (wpc != null && wpc.hasThread()) {
            //step 2 b 當前APP行程已經存在 直接啟動對應Activity
            try {
                realStartActivityLocked(r, wpc, andResume, checkConfig);
                return;
            } catch (RemoteException e) {
                Slog.w(TAG, "Exception when starting activity "
                        + r.intent.getComponent().flattenToShortString(), e);
            }

            // If a dead object exception was thrown -- fall through to
            // restart the application.
            knownToBeDead = true;
        }

        r.notifyUnknownVisibilityLaunchedForKeyguardTransition();

        final boolean isTop = andResume && r.isTopRunningActivity();
        //step 2 a 當前APP行程不存在 呼叫 Zygote行程去fork APP行程
        mService.startProcessAsync(r, knownToBeDead, isTop, isTop ? "top-activity" : "activity");
    }

未完待續，，，

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