主要對(duì)象介紹

• ActivityManagerService：負(fù)責(zé)系統(tǒng)中所有Activity的生命周期捂寿；
• ActivityThread：App的真正入口刹泄，當(dāng)App啟動(dòng)后诊胞，會(huì)調(diào)用其main方法開始執(zhí)行庸队，開啟消息循環(huán)隊(duì)列刁卜。是傳說中的UI線程软瞎，即主線程逢唤。與ActivityManagerService配合，一起完成Activity的管理工作涤浇；
• ApplicationThread：用來實(shí)現(xiàn)ActivityManagerService與ActivityThread之間的交互鳖藕。在ActivityManagerService需要管理相關(guān)Application中的Activity的生命周期，通過ApplicationThread的代理對(duì)象與ActivityThread通訊只锭；
• ApplictationThreadProxy：是ApplicationThread在服務(wù)端的代理對(duì)象著恩，負(fù)責(zé)和客戶端的ApplicationThread通訊。AMS就是通過這個(gè)代理對(duì)象與ActivityThread進(jìn)行通信的蜻展，Android 8.0上以刪除該類喉誊，采用AIDL接口的方式來進(jìn)行IPC，實(shí)現(xiàn)RPC操作纵顾；
• Instrumentation：每一個(gè)應(yīng)用程序都只有一個(gè)Instrumentation對(duì)象伍茄，每個(gè)Activity內(nèi)都有一個(gè)對(duì)該對(duì)象的引用。Instrumentation可以理解為應(yīng)用進(jìn)程的管家施逾，ActivityThread要?jiǎng)?chuàng)建或者打開某個(gè)Activity時(shí)敷矫，都需要通過Instrumentation來進(jìn)行具體的操作；
• ActvitityStack：Activity在AMS的棧管理汉额，用來記錄已經(jīng)啟動(dòng)的Activity的先后關(guān)系曹仗、狀態(tài)信息等。通過ActivityStack決定是否需要啟動(dòng)新的進(jìn)程蠕搜；
• ActivityRecord：ActivityStatck的管理對(duì)象怎茫，每個(gè)Activity在AMS對(duì)應(yīng)的一個(gè)ActivityRecord，來記錄Activity的狀態(tài)以及其他信息讥脐≡饩樱可以理解為Activity在服務(wù)端的Activity對(duì)象的映射；
• ActivityClientRecord：與ActivityRecord是在服務(wù)端（AMS）的記錄相對(duì)應(yīng)旬渠，是Activity在客戶端（ActivityThread）的記錄俱萍；
• TaskRecord：AMS抽象出來的任務(wù)棧的概念。一個(gè)TaskRecord包含若干個(gè)ActivityRecord告丢。ASM用它來確保Activity啟動(dòng)和退出順序枪蘑。它與Activity的啟動(dòng)模式直接相關(guān)。
• ActivityStarter：啟動(dòng)Activity的控制器，主要用于用來將Intent和flags轉(zhuǎn)換成activity和相關(guān)任務(wù)棧岳颇；
• ActivityStackSupervisor：主要管理著mHomeStack和mFocusedStack兩個(gè)ActivityStack等相關(guān)信息照捡；

Binder通信

• 在Android 8.0以前，Binder通信的流程如下：
  客戶端： ActivityManagerProxy -> Binder驅(qū)動(dòng) -> 服務(wù)端：ActivityManagerService
  服務(wù)端： ApplicationThreadProxy -> Binder驅(qū)動(dòng) -> 客戶端：ApplicationThread
• Android8.0開始话侧，刪除了ActivityManagerNative栗精，AMS的繼承類也發(fā)生了變化，繼承了IActivityManager.Stub接口類瞻鹏。了解Android的Binder機(jī)制應(yīng)該知道悲立，這里IActivityManager.aidl生成的接口類。Android8.0開始新博，把一些Binder代碼轉(zhuǎn)化為了AIDL模板方式：

public class ActivityManagerService extends IActivityManager.Stub
        implements Watchdog.Monitor, BatteryStatsImpl.BatteryCallback

ActivityManager中的代碼：

    public static IActivityManager getService() {
        return IActivityManagerSingleton.get();
    }

    private static final Singleton<IActivityManager> IActivityManagerSingleton =
            new Singleton<IActivityManager>() {
                @Override
                protected IActivityManager create() {
                    final IBinder b = ServiceManager.getService(Context.ACTIVITY_SERVICE);
                    final IActivityManager am = IActivityManager.Stub.asInterface(b);
                    return am;
                }
            };

• 而在Android7.0及其以前的版本上,則是客戶端通過ActivityManaagerProxy與服務(wù)端的ActivityManager進(jìn)行通信的
  ActivityManagerNative:

**
*獲得IActivityManager類
*/
static public IActivityManager getDefault() {
        return gDefault.get();
    }

static public IActivityManager asInterface(IBinder obj) {
        if (obj == null) {
            return null;
        }
        IActivityManager in =
            (IActivityManager)obj.queryLocalInterface(descriptor);
        if (in != null) {
            return in;
        }
 
        return new ActivityManagerProxy(obj);

}

ActivityManager:

private static final Singleton<IActivityManager> gDefault = new Singleton<IActivityManager>() {
        protected IActivityManager create() {
            IBinder b = ServiceManager.getService("activity");
            if (false) {
                Log.v("ActivityManager", "default service binder = " + b);
            }
            IActivityManager am = asInterface(b);//注意這一行
            if (false) {
                Log.v("ActivityManager", "default service = " + am);
            }
            return am;
        }
};

可以看出來薪夕，兩個(gè)寫法不一樣，本質(zhì)上都是一樣的赫悄，Android 8.0可能使用了AIDL方式進(jìn)行ipc原献。

• 同理，ApplicationThread同上述一樣做了更改：

 private class ApplicationThread extends IApplicationThread.Stub {
    ...
 }

所以在Android 8.0上不存在ActivityManagerProxy和ApplicationThreadProxy埂淮，而是采用了AIDL接口的方式來進(jìn)行通信的姑隅。

源碼調(diào)用棧(基于Android 8.0)

按照自上而下的調(diào)用棧的順序進(jìn)行調(diào)用，以類文件為單位來計(jì)步同诫，方便大家去了解調(diào)用流程粤策，主要涉及的幾個(gè)源文件：Instumentation,ActivityMangerService,ActivityStack,ActivityStarter,ActivityStackSupervisor,ActivityThread,Activity等。

1. Activity

public void startActivity(Intent intent)
    
public void startActivity(Intent intent, @Nullable Bundle options)

public void startActivityForResult(@RequiresPermission Intent intent, int requestCode,
            @Nullable Bundle options)

2. Intrumentation

public ActivityResult execStartActivity(
    Context who, IBinder contextThread, IBinder token, Activity target,
    Intent intent, int requestCode, Bundle options){
    ...
    int result = ActivityManager.getService()
        .startActivity(whoThread, who.getBasePackageName(), intent,
            intent.resolveTypeIfNeeded(who.getContentResolver()),
            token, target != null ? target.mEmbeddedID : null,
            requestCode, 0, null, options);
    ...
}

3. ActivityManagerService

public final int startActivity(IApplicationThread caller, String callingPackage,
    Intent intent, String resolvedType, IBinder resultTo, String resultWho, int requestCode,
    int startFlags, ProfilerInfo profilerInfo, Bundle bOptions) {
    ...
    return startActivityAsUser(caller, callingPackage, intent, resolvedType, resultTo,
                resultWho, requestCode, startFlags, profilerInfo, bOptions,
                UserHandle.getCallingUserId());
}
     
            
public final int startActivityAsUser(IApplicationThread caller, String callingPackage,
    Intent intent, String resolvedType, IBinder resultTo, String resultWho, int requestCode,
            int startFlags, ProfilerInfo profilerInfo, Bundle bOptions, int userId) {
    ...
    return mActivityStarter.startActivityMayWait(caller, -1, callingPackage, intent,
                resolvedType, null, null, resultTo, resultWho, requestCode, startFlags,
                profilerInfo, null, null, bOptions, false, userId, null, "startActivityAsUser");
}

4. ActivityStarter

final int startActivityMayWait(IApplicationThread caller, int callingUid,
    String callingPackage, Intent intent, String resolvedType,
    IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
    IBinder resultTo, String resultWho, int requestCode, int startFlags,
    ProfilerInfo profilerInfo, WaitResult outResult,
    Configuration globalConfig, Bundle bOptions, boolean ignoreTargetSecurity, 
    int userId,askRecord inTask, String reason) { 
    ...
    int res = startActivityLocked(caller, intent, ephemeralIntent, resolvedType,
        aInfo, rInfo, voiceSession, voiceInteractor,
        resultTo, resultWho, requestCode, callingPid,
        callingUid, callingPackage, realCallingPid, realCallingUid, startFlags,
        options, ignoreTargetSecurity, componentSpecified, outRecord, inTask,
        reason);
    ...
}
        

int startActivityLocked(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,
    ActivityOptions options, boolean ignoreTargetSecurity, boolean componentSpecified,
    ActivityRecord[] outActivity, TaskRecord inTask, String reason) {
    ...
    mLastStartActivityResult = startActivity(caller, intent, ephemeralIntent, resolvedType,
    aInfo, rInfo, voiceSession, voiceInteractor, resultTo, resultWho, requestCode,
    callingPid, callingUid, callingPackage, realCallingPid, realCallingUid, startFlags,
    options, ignoreTargetSecurity, componentSpecified, mLastStartActivityRecord,
            inTask);
    ...
}
            
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,
    ActivityOptions options, boolean ignoreTargetSecurity, boolean componentSpecified,
    ActivityRecord[] outActivity, TaskRecord inTask) {
    ...
    doPendingActivityLaunchesLocked(false);
    return startActivity(r, sourceRecord, voiceSession, voiceInteractor, startFlags, true,
    options, inTask, outActivity);
}
            

private int startActivity(final ActivityRecord r, ActivityRecord sourceRecord,
    IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
    int startFlags, boolean doResume, ActivityOptions options, TaskRecord inTask,
    ActivityRecord[] outActivity) {
    ...
    result = startActivityUnchecked(r, sourceRecord, voiceSession, voiceInteractor,
        startFlags, doResume, options, inTask, outActivity);
    ...
}  
            
private int startActivityUnchecked(final ActivityRecord r, ActivityRecord sourceRecord,
    IVoiceInteractionSession voiceSession, IVoiceInteractor voiceInteractor,
    int startFlags, boolean doResume, ActivityOptions options, TaskRecord inTask,
    ActivityRecord[] outActivity) {
    ...
    if (mDoResume) {
        mSupervisor.resumeFocusedStackTopActivityLocked();
    }
    ...
}

5. ActivityStackSupervisor

boolean resumeFocusedStackTopActivityLocked() {
    return resumeFocusedStackTopActivityLocked(null, null, null);
}
    
boolean resumeFocusedStackTopActivityLocked(
    ActivityStack targetStack, ActivityRecord target, ActivityOptions targetOptions) {
    ...
    if (r == null || r.state != RESUMED) {
        mFocusedStack.resumeTopActivityUncheckedLocked(null, null);
    } 
    ...
}

7. ActivityStack

boolean resumeTopActivityUncheckedLocked(ActivityRecord prev, ActivityOptions options) {
    ...
    result = resumeTopActivityInnerLocked(prev, options);
    ...
}

private boolean resumeTopActivityInnerLocked(ActivityRecord prev, ActivityOptions options) { 
   ....
    if (mResumedActivity != null) {
        //同步等待pause當(dāng)前Activity的結(jié)果
        pausing |= startPausingLocked(userLeaving, false, next, false);
    }
    ....
      //開始啟動(dòng)下一個(gè)Activity
      mStackSupervisor.startSpecificActivityLocked(next, true, false);
    ....
}


final boolean startPausingLocked(boolean userLeaving, boolean uiSleeping, ActivityRecord resuming, boolean pauseImmediately) {
    ....
    //去當(dāng)前Activity所在應(yīng)用進(jìn)程暫停當(dāng)前activity
     prev.app.thread.schedulePauseActivity(prev.appToken, prev.finishing,
            userLeaving, prev.configChangeFlags, pauseImmediately);
    ....
}
       

8. ActivityThread$ApplicationThread

public final void schedulePauseActivity(IBinder token, boolean finished, boolean userLeaving, int configChanges, boolean dontReport) {
    ...
    sendMessage(finished ? H.PAUSE_ACTIVITY_FINISHING: H.PAUSE_ACTIVITY, token,
    (userLeaving ? USER_LEAVING: 0) | (dontReport ? DONT_REPORT: 0), configChanges, seq);
    ...
}

9. ActivityThread

private void sendMessage(int what, Object obj, int arg1, int arg2, int seq) {
    Message msg = Message.obtain();
    ....
    mH.sendMessage(msg);
}

10. ActivityThread$H

public void handleMessage(Message msg) {
   ...
    switch (msg.what) {
    case PAUSE_ACTIVITY:
        {
            SomeArgs args = (SomeArgs) msg.obj;
            handlePauseActivity((IBinder) args.arg1, false, (args.argi1 & USER_LEAVING) != 0,
            args.argi2, (args.argi1 & DONT_REPORT) != 0, args.argi3);
        }
        break;
    }
    ...
}

11. ActivityThread

private void handlePauseActivity(IBinder token, boolean finished, 
    boolean userLeaving, int configChanges, boolean dontReport, int seq) {
    ...
    performPauseActivity(token, finished, r.isPreHoneycomb(), "handlePauseActivity");
    ...
    //執(zhí)行完后通知AMS當(dāng)前Activity已經(jīng)pause
    ActivityManager.getService().activityPaused(token);
    ...
}

final Bundle performPauseActivity(ActivityClientRecord r, boolean finished,
     boolean saveState, String reason) {
         ...
         performPauseActivityIfNeeded(r, reason);
         ...
}


private void performPauseActivityIfNeeded(ActivityClientRecord r, String reason) {
    ...
     mInstrumentation.callActivityOnPause(r.activity);
    ...
}

12. Instrumentation

public void callActivityOnPause(Activity activity) {
    activity.performPause();
}

13. Activity

final void performPause() {
    ...
    onPause();
    ...
}

由于在ActivityThread中handlePauseActivity的方法里误窖，在pause成功后，需要通知AMS已經(jīng)pause成功秩贰，所以接著分析ActivityManagerService.activityPaused方法霹俺。

14. ActivityManagerService

public final void activityPaused(IBinder token) {
    final long origId = Binder.clearCallingIdentity();
    synchronized(this) {
        ActivityStack stack = ActivityRecord.getStackLocked(token);
        if (stack != null) {
            stack.activityPausedLocked(token, false);
        }
    }
    Binder.restoreCallingIdentity(origId);
}

15. ActivityStack

final void activityPausedLocked(IBinder token, boolean timeout) {
    ...
    mHandler.removeMessages(PAUSE_TIMEOUT_MSG, r);
    ...
    completePauseLocked(true /* resumeNext */, null /* resumingActivity */);
    ...
}

private void completePauseLocked(boolean resumeNext, ActivityRecord resuming) {
    ...
    mStackSupervisor.resumeFocusedStackTopActivityLocked(topStack, prev, null);
    ...
}

16. ActivityStackSupervisor

boolean resumeFocusedStackTopActivityLocked(ActivityStack targetStack, ActivityRecord target, ActivityOptions targetOptions) {
    //如果啟動(dòng)Activity和要啟動(dòng)的Activity在同一個(gè)ActivityStack中，調(diào)用targetStack對(duì)象的方法
    if (targetStack != null && isFocusedStack(targetStack)) {
        return targetStack.resumeTopActivityUncheckedLocked(target, targetOptions);
    }
    //如果不在同一個(gè)ActivityStack中毒费，則調(diào)用mFocusStack對(duì)象的方法
    if (r == null || r.state != RESUMED) {
        mFocusedStack.resumeTopActivityUncheckedLocked(null, null);
    }

    return false;
}

17. ActivityStatck

boolean resumeTopActivityUncheckedLocked(ActivityRecord prev, ActivityOptions options) {
    ...
    result = resumeTopActivityInnerLocked(prev, options);
    ...
}

private boolean resumeTopActivityInnerLocked(ActivityRecord prev, ActivityOptions options) { 
   ...
    if (mResumedActivity != null) {
        //同步等待pause當(dāng)前Activity的結(jié)果,但在pause時(shí)丙唧，已經(jīng)把mResumedActivity置為了null，所以不走這里
        pausing |= startPausingLocked(userLeaving, false, next, false);
        ...
    }
    ...
    return true;
    ...
      //開始啟動(dòng)下一個(gè)Activity
      mStackSupervisor.startSpecificActivityLocked(next, true, false);
    ...
}

18. ActivityStackSupervisor

void startSpecificActivityLocked(ActivityRecord r,
    boolean andResume, boolean checkConfig) { 
    if (app != null && app.thread != null) { 
        ...
        realStartActivityLocked(r, app, andResume, checkConfig);
        return;
    }
    ...
    //啟動(dòng)跨進(jìn)程的Activity需要先開啟新的應(yīng)用進(jìn)程
    mService.startProcessLocked(r.processName, r.info.applicationInfo, true, 0,
        "activity", r.intent.getComponent(), false, false, true);
}

final boolean realStartActivityLocked(ActivityRecord r, ProcessRecord app,
    boolean andResume, boolean checkConfig) throws RemoteException { 
    ...
    app.thread.scheduleLaunchActivity(new Intent(r.intent), r.appToken,
        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, !andResume,
        mService.isNextTransitionForward(), profilerInfo);
    ...
}

19. ActivityThread$ApplicationThread

public final void scheduleLaunchActivity(Intent intent, IBinder token, int ident,
    ActivityInfo info, Configuration curConfig, Configuration overrideConfig,
    CompatibilityInfo compatInfo, String referrer, IVoiceInteractor voiceInteractor,
    int procState, Bundle state, PersistableBundle persistentState,
    List<ResultInfo> pendingResults, List<ReferrerIntent> pendingNewIntents,
    boolean notResumed, boolean isForward, ProfilerInfo profilerInfo) {
    ...
    sendMessage(H.LAUNCH_ACTIVITY, r);
}

20. ActivityThread

private void sendMessage(int what, Object obj) {
    sendMessage(what, obj, 0, 0, false);
}
 
 
private void sendMessage(int what, Object obj, int arg1, int arg2, boolean async) {
    ...
    mH.sendMessage(msg);
} 
 

21. ActivityThread$H

public void handleMessage(Message msg) {
    ...
    switch (msg.what) {
    case LAUNCH_ACTIVITY:
        {
            ....
            handleLaunchActivity(r, null, "LAUNCH_ACTIVITY");
            ....
        }
        break;
        ...
    }
}

22. ActivityThread

private void handleLaunchActivity(ActivityClientRecord r, Intent customIntent, String reason) {
    ...
    Activity a = performLaunchActivity(r, customIntent);
}

private Activity performLaunchActivity(ActivityClientRecord r, Intent customIntent){ 
    ...
    if (r.isPersistable()) {
        mInstrumentation.callActivityOnCreate(activity, r.state, r.persistentState);
    } else {
        mInstrumentation.callActivityOnCreate(activity, r.state);
    }
    ...
}

23. Instumentation

public void callActivityOnCreate(Activity activity, Bundle icicle) {
    prePerformCreate(activity);
    activity.performCreate(icicle);
    postPerformCreate(activity);
}

24. Activity

final void performCreate(Bundle icicle) {
    performCreate(icicle, null);
}

final void performCreate(Bundle icicle, PersistableBundle persistentState) {
    ...
    if (persistentState != null) {
        onCreate(icicle, persistentState);
    } else {
        onCreate(icicle);
    }
   ...
}

Activity啟動(dòng)流程

為了敘述方便觅玻，我們假設(shè)Activity A要啟動(dòng)Activity B想际。

1. Activity A向AMS發(fā)送一個(gè)啟動(dòng)Activity B的進(jìn)程間通信請(qǐng)求；
2. AMS會(huì)將要啟動(dòng)的Activity B的組件信息保存下來溪厘，然后通過Binder通信（ApplicationThread及其接口定義語言）胡本，讓Activity A執(zhí)行pause操作；
3. Activity B完成pause操作后畸悬，通過Binder通信（ActivityManagerService及其接口定義語言）通知AMS侧甫，可以執(zhí)行啟動(dòng)Activity B的操作了（要啟動(dòng)的activity信息保存在了棧頂）；
4. 在啟動(dòng)之前，如果發(fā)現(xiàn)Activity B的應(yīng)用程序進(jìn)程不存在披粟，會(huì)先啟動(dòng)一個(gè)新的進(jìn)程（上述調(diào)用棧沒涉及咒锻，同學(xué)們可自行查看源碼）；
5. AMS執(zhí)行一系列啟動(dòng)Activity B的操作守屉，并通過Binder通信（ApplicationThread及其接口定義語言）進(jìn)行跨進(jìn)程調(diào)用惑艇，將Activity B啟動(dòng)起來；

關(guān)于AMS

• AMS的啟動(dòng)是在SystemServer（系統(tǒng)進(jìn)程）中啟動(dòng)的拇泛，同其他Android應(yīng)用一樣敦捧，也是由Zygote進(jìn)程fork出來的：

public final class SystemServer {

    /**
     * The main entry point from zygote.
     * 注釋寫的很清楚了，SystemServer進(jìn)程是有Zygote進(jìn)程fork出來的
     */
    public static void main(String[] args) {
        new SystemServer().run();
    }    
    
    private void run() {
        ...
         startBootstrapServices();
        ...
    }
    
    private void startBootstrapServices() {
        ...
        // Activity manager runs the show.
        traceBeginAndSlog("StartActivityManager");
        //開啟ActivityManagerService進(jìn)程
        mActivityManagerService = mSystemServiceManager.startService(
                ActivityManagerService.Lifecycle.class).getService();
        mActivityManagerService.setSystemServiceManager(mSystemServiceManager);
        mActivityManagerService.setInstaller(installer);
        traceEnd();        
        ...
    }    
}

• AMS與APP進(jìn)程的通信：

1. APP進(jìn)程通過IActivityManager.aidl接口向AMS進(jìn)程進(jìn)行通信碰镜。
   ActivityManager.getService()獲得AMS的Binder接口兢卵，再通過Stub.asInterface的方式，轉(zhuǎn)成IActivityManager的接口绪颖，通過IActivityManager與AMS進(jìn)行通信秽荤，實(shí)現(xiàn)RPC遠(yuǎn)程跨進(jìn)程調(diào)用；
   Instrumentation

int result = ActivityManager.getService()
                .startActivity(whoThread, who.getBasePackageName(), intent,
                        intent.resolveTypeIfNeeded(who.getContentResolver()),
                        token, target, requestCode, 0, null, options);

ActivityManager

public static IActivityManager getService() {
        return IActivityManagerSingleton.get();
}
 
private static final Singleton<IActivityManager> IActivityManagerSingleton =
    new Singleton<IActivityManager>() {
        @Override
        protected IActivityManager create() {
            final IBinder b = ServiceManager.getService(Context.ACTIVITY_SERVICE);
            final IActivityManager am = IActivityManager.Stub.asInterface(b);
            return am;
        }
};

2. AMS進(jìn)程通過IApplication.aidl接口向APP進(jìn)程進(jìn)行通信柠横。
   在AMS內(nèi)部持有每個(gè)ActivityThread的IApplicatinThread接口實(shí)例窃款，用時(shí)可以直接調(diào)用。同IActivityManager,也是通過Binder進(jìn)行進(jìn)程間通信牍氛。

參考鏈接
【凱子哥帶你學(xué)Framework】Activity啟動(dòng)過程全解析
Activity啟動(dòng)流程簡直喪心病狂晨继！