Android P ActivityManagerService（五） startActivity的第三小部分

最新推荐文章于 2022-08-22 09:14:33 发布

三三不尽

最新推荐文章于 2022-08-22 09:14:33 发布

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分类专栏： Android

本文链接：https://blog.youkuaiyun.com/weixin_39821531/article/details/89450444

本文详细剖析了Android P中ActivityManagerService的startActivity方法，涉及300行代码的逻辑，包括错误处理、Bundle操作、ProcessRecord获取、权限检查、ActivityRecord构建等多个环节。通过层层安检，最终生成ActivityRecord并准备启动Activity。

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ActivityStarter中的startActivity方法；这是一个有300行长度方法；总体是这样的；

private int startActivity(IApplicationThread caller, Intent intent, Intent ephemeralIntent,
        String resolvedType, ActivityInfo aInfo, ResolveInfo rInfo,
        IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
        IBinder resultTo, String resultWho, int requestCode, int callingPid, int callingUid,
        String callingPackage, int realCallingPid, int realCallingUid, int startFlags,
        SafeActivityOptions options,
        boolean ignoreTargetSecurity, boolean componentSpecified, ActivityRecord[] outActivity,
        TaskRecord inTask, boolean allowPendingRemoteAnimationRegistryLookup) {
    int err = ActivityManager.START_SUCCESS;
    // Pull the optional Ephemeral Installer-only bundle out of the options early.
    final Bundle verificationBundle
            = options != null ? options.popAppVerificationBundle() : null;

    ProcessRecord callerApp = null;
    if (caller != null) {
        callerApp = mService.getRecordForAppLocked(caller);
        if (callerApp != null) {
            callingPid = callerApp.pid;
            callingUid = callerApp.info.uid;
        } else {
            Slog.w(TAG, "Unable to find app for caller " + caller
                    + " (pid=" + callingPid + ") when starting: "
                    + intent.toString());
            err = ActivityManager.START_PERMISSION_DENIED;
        }
    }

    final int userId = aInfo != null && aInfo.applicationInfo != null
            ? UserHandle.getUserId(aInfo.applicationInfo.uid) : 0;

    if (err == ActivityManager.START_SUCCESS) {
        Slog.i(TAG, "START u" + userId + " {" + intent.toShortString(true, true, true, false)
                + "} from uid " + callingUid);
    }

    ActivityRecord sourceRecord = null;
    ActivityRecord resultRecord = null;
    if (resultTo != null) {
        sourceRecord = mSupervisor.isInAnyStackLocked(resultTo);
        if (DEBUG_RESULTS) Slog.v(TAG_RESULTS,
                "Will send result to " + resultTo + " " + sourceRecord);
        if (sourceRecord != null) {
            if (requestCode >= 0 && !sourceRecord.finishing) {
                resultRecord = sourceRecord;
            }
        }
    }

    final int launchFlags = intent.getFlags();

    if ((launchFlags & Intent.FLAG_ACTIVITY_FORWARD_RESULT) != 0 && sourceRecord != null) {
        // Transfer the result target from the source activity to the new
        // one being started, including any failures.
        if (requestCode >= 0) {
            SafeActivityOptions.abort(options);
            return ActivityManager.START_FORWARD_AND_REQUEST_CONFLICT;
        }
        resultRecord = sourceRecord.resultTo;
        if (resultRecord != null && !resultRecord.isInStackLocked()) {
            resultRecord = null;
        }
        resultWho = sourceRecord.resultWho;
        requestCode = sourceRecord.requestCode;
        sourceRecord.resultTo = null;
        if (resultRecord != null) {
            resultRecord.removeResultsLocked(sourceRecord, resultWho, requestCode);
        }
        if (sourceRecord.launchedFromUid == callingUid) {
            // The new activity is being launched from the same uid as the previous
            // activity in the flow, and asking to forward its result back to the
            // previous.  In this case the activity is serving as a trampoline between
            // the two, so we also want to update its launchedFromPackage to be the
            // same as the previous activity.  Note that this is safe, since we know
            // these two packages come from the same uid; the caller could just as
            // well have supplied that same package name itself.  This specifially
            // deals with the case of an intent picker/chooser being launched in the app
            // flow to redirect to an activity picked by the user, where we want the final
            // activity to consider it to have been launched by the previous app activity.
            callingPackage = sourceRecord.launchedFromPackage;
        }
    }

    if (err == ActivityManager.START_SUCCESS && intent.getComponent() == null) {
        // We couldn't find a class that can handle the given Intent.
        // That's the end of that!
        err = ActivityManager.START_INTENT_NOT_RESOLVED;
    }

    if (err == ActivityManager.START_SUCCESS && aInfo == null) {
        // We couldn't find the specific class specified in the Intent.
        // Also the end of the line.
        err = ActivityManager.START_CLASS_NOT_FOUND;
    }

    if (err == ActivityManager.START_SUCCESS && sourceRecord != null
            && sourceRecord.getTask().voiceSession != null) {
        // If this activity is being launched as part of a voice session, we need
        // to ensure that it is safe to do so.  If the upcoming activity will also
        // be part of the voice session, we can only launch it if it has explicitly
        // said it supports the VOICE category, or it is a part of the calling app.
        if ((launchFlags & FLAG_ACTIVITY_NEW_TASK) == 0
                && sourceRecord.info.applicationInfo.uid != aInfo.applicationInfo.uid) {
            try {
                intent.addCategory(Intent.CATEGORY_VOICE);
                if (!mService.getPackageManager().activitySupportsIntent(
                        intent.getComponent(), intent, resolvedType)) {
                    Slog.w(TAG,
                            "Activity being started in current voice task does not support voice: "
                                    + intent);
                    err = ActivityManager.START_NOT_VOICE_COMPATIBLE;
                }
            } catch (RemoteException e) {
                Slog.w(TAG, "Failure checking voice capabilities", e);
                err = ActivityManager.START_NOT_VOICE_COMPATIBLE;
            }
        }
    }

    if (err == ActivityManager.START_SUCCESS && voiceSession != null) {
        // If the caller is starting a new voice session, just make sure the target
        // is actually allowing it to run this way.
        try {
            if (!mService.getPackageManager().activitySupportsIntent(intent.getComponent(),
                    intent, resolvedType)) {
                Slog.w(TAG,
                        "Activity being started in new voice task does not support: "
                                + intent);
                err = ActivityManager.START_NOT_VOICE_COMPATIBLE;
            }
        } catch (RemoteException e) {
            Slog.w(TAG, "Failure checking voice capabilities", e);
            err = ActivityManager.START_NOT_VOICE_COMPATIBLE;
        }
    }

    final ActivitySta