Android 11（platfrom 30）APP启动流程（含Activity）核心点记录

Posted 2021-06-28 安卓开发-顺

前言：边分析，边记录 不断更新

场景一、从桌面点击APP图标进行启动

涉及到的核心进程：

step 1：

解析androidManifest文件 组装Intent对象

--> Activity --- startActivity

--> Activity --- startActivityForResult

--> Instrumentation --- execStartActivity

      --- ActivityTaskManager.getService().startActivity 此处是通过Binder跨进程通信 去调用系统进         程SystemService 的ActivityMangerService 以下简称AMS

--> AMS --- startActivity

--> ActivityTaskManagerService --- startActivity  1043行

--> ActivityTaskManagerService --- startActivityAsUser  1068行

--> ActivityTaskManagerService --- startActivityAsUser  1077行

     --- getActivityStartController().obtainStarter  这里得到了一个 ActivityStarter对象

--> 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

这里是核心代码 是step 2 a 和 step 2 b的分支判断的地方

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 当前APP进程已经存在 直接启动对应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 当前APP进程不存在 调用 Zygote进程去fork APP进程
        mService.startProcessAsync(r, knownToBeDead, isTop, isTop ? "top-activity" : "activity");
    }

未完待续。。。