【Android 启动过程】Activity 启动源码分析 ( ActivityThread 流程分析 二 )

public class ActivityManagerService extends IActivityManager.Stub
        implements Watchdog.Monitor, BatteryStatsImpl.BatteryCallback {
  // 为 ActivityThread 绑定 ApplicationThread 主方法
    private final boolean attachApplicationLocked(IApplicationThread thread,
            int pid) {
        try {
            checkTime(startTime, "attachApplicationLocked: immediately before bindApplication");
            mStackSupervisor.mActivityMetricsLogger.notifyBindApplication(app);
    // 在此处为 ActivityThread 绑定 ApplicationThread , 此时又回到 ActivityThread
            if (app.instr != null) {
                thread.bindApplication(processName, appInfo, providers,
                        app.instr.mClass,
                        profilerInfo, app.instr.mArguments,
                        app.instr.mWatcher,
                        app.instr.mUiAutomationConnection, testMode,
                        mBinderTransactionTrackingEnabled, enableTrackAllocation,
                        isRestrictedBackupMode || !normalMode, app.persistent,
                        new Configuration(getGlobalConfiguration()), app.compat,
                        getCommonServicesLocked(app.isolated),
                        mCoreSettingsObserver.getCoreSettingsLocked(),
                        buildSerial);
            } else {
                thread.bindApplication(processName, appInfo, providers, null, profilerInfo,
                        null, null, null, testMode,
                        mBinderTransactionTrackingEnabled, enableTrackAllocation,
                        isRestrictedBackupMode || !normalMode, app.persistent,
                        new Configuration(getGlobalConfiguration()), app.compat,
                        getCommonServicesLocked(app.isolated),
                        mCoreSettingsObserver.getCoreSettingsLocked(),
                        buildSerial);
            }
        } catch (Exception e) {
        }
        // 查看顶部可见 Activity 是否正在等待在此进程中运行
        if (normalMode) {
            try {
                if (mStackSupervisor.attachApplicationLocked(app)) {
                    didSomething = true;
                }
            } catch (Exception e) {
                Slog.wtf(TAG, "Exception thrown launching activities in " + app, e);
                badApp = true;
            }
        }
        return true;
    }
}

public class ActivityStackSupervisor extends ConfigurationContainer implements DisplayListener,
        RecentTasks.Callbacks {
    boolean attachApplicationLocked(ProcessRecord app) throws RemoteException {
          // 省略其它代码 , 在此处调用了 realStartActivityLocked 方法 
                            if (realStartActivityLocked(activity, app,
                                    top == activity /* andResume */, true /* checkConfig */)) {
                                didSomething = true;
                            }
        return didSomething;
    }
}

public class ActivityStackSupervisor extends ConfigurationContainer implements DisplayListener,
        RecentTasks.Callbacks {
    final boolean realStartActivityLocked(ActivityRecord r, ProcessRecord app,
                                          boolean andResume, boolean checkConfig) throws RemoteException {
        if (!allPausedActivitiesComplete()) {
            // 当有活动暂停时，我们将跳过开始任何新活动，直到暂停完成。
            // 注意：对于在暂停状态下启动的活动，我们也会这样做，因为它们将首先恢复，然后在客户端暂停。
            if (DEBUG_SWITCH || DEBUG_PAUSE || DEBUG_STATES) Slog.v(TAG_PAUSE,
                    "realStartActivityLocked: Skipping start of r=" + r
                            + " some activities pausing...");
            return false;
        }
        final TaskRecord task = r.getTask();
        final ActivityStack stack = task.getStack();
        beginDeferResume();
        try {
            r.startFreezingScreenLocked(app, 0);
            // 安排启动时间以收集有关慢速应用程序的信息。
            r.startLaunchTickingLocked();
            r.setProcess(app);
            if (getKeyguardController().isKeyguardLocked()) {
                r.notifyUnknownVisibilityLaunched();
            }
            // 让窗口管理器根据新的活动顺序重新评估屏幕方向。
            // 注意，这样做的结果是，它可以使用新的方向调用activity manager。
            // 我们不关心这一点，因为活动当前未运行，所以我们只是重新启动它。
            if (checkConfig) {
                // 推迟恢复，因为我们将很快启动新活动。
                // 我们不希望在确保配置和尝试恢复重点堆栈的顶级活动的同时，重复启动同一记录。
                ensureVisibilityAndConfig(r, r.getDisplayId(),
                        false /* markFrozenIfConfigChanged */, true /* deferResume */);
            }
            if (r.getStack().checkKeyguardVisibility(r, true /* shouldBeVisible */,
                    true /* isTop */)) {
                // 仅当基于keyguard状态允许活动可见时，我们才将可见性设置为true。
                // 这样可以避免在窗口管理器中将此设置为运动状态，
                // 而由于以后的调用而取消该设置，以确保将可见性设置回false的可见活动。
                r.setVisibility(true);
            }
            try {
                // 下面的代码是启动 Activity 的核心代码
                // Create activity launch transaction.
                final ClientTransaction clientTransaction = ClientTransaction.obtain(app.thread,
                        r.appToken);
                clientTransaction.addCallback(LaunchActivityItem.obtain(new Intent(r.intent),
                        System.identityHashCode(r), r.info,
                        // TODO: Have this take the merged configuration instead of separate global
                        // and override configs.
                        mergedConfiguration.getGlobalConfiguration(),
                        mergedConfiguration.getOverrideConfiguration(), r.compat,
                        r.launchedFromPackage, task.voiceInteractor, app.repProcState, r.icicle,
                        r.persistentState, results, newIntents, mService.isNextTransitionForward(),
                        profilerInfo));
                // 设置所需的最终状态。配置生命周期
                final ActivityLifecycleItem lifecycleItem;
                if (andResume) {
                    // 开启新的 Activity
                    lifecycleItem = ResumeActivityItem.obtain(mService.isNextTransitionForward());
                } else {
                    // 终止 Activity
                    lifecycleItem = PauseActivityItem.obtain();
                }
                clientTransaction.setLifecycleStateRequest(lifecycleItem);
                // 安排事务。
                mService.getLifecycleManager().scheduleTransaction(clientTransaction);
                // 上面的代码是启动 Activity 的核心代码
            } catch (RemoteException e) {
            }
        } finally {
            endDeferResume();
        }
        return true;
    }
}