本文主要從3個方面來介紹這ActivityDisplay/ActivityStack/TaskRecord/ActivityRecord的關(guān)系幾個類之間的關(guān)系，先從整體關(guān)系圖，對4個類的關(guān)系有個大概的了解，然后通過dumpsys命令，來驗(yàn)證這種關(guān)系；然后從類定義的角度來看，4個類是如何互相包含的；最后從Activity啟動的流程過程來看4個類是如何關(guān)聯(lián)上來的。

通過閱讀本文，能對ActivityDisplay/ActivityStack/TaskRecord/ActivityRecord的關(guān)系有個整體的認(rèn)識和理解

1.整體關(guān)系圖如下

image.png

說明：
1.在#0的ActivityDisplay上，總共有2個Stack，代表2個應(yīng)用
2.在Stack #4里面，有一個TaskRecord，Task id #87
3.在TaskRecord里面，Activities列表里面只有一個ActivityRecord

ACTIVITY MANAGER ACTIVITIES (dumpsys activity activities)
Display #0 (activities from top to bottom):

  Stack #4: type=standard mode=fullscreen
  isSleeping=false
  mBounds=Rect(0, 0 - 0, 0)
    Task id #87
    * TaskRecord{3a93f6f #87 A=com.android.deskclock U=0 StackId=4 sz=1}
      userId=0 effectiveUid=u0a93 mCallingUid=u0a81 mUserSetupComplete=true mCallingPackage=com.android.launcher3
      intent={act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.android.deskclock/.DeskClock}
      Activities=[ActivityRecord{ed5f802 u0 com.android.deskclock/.DeskClock t87}]
      mRootProcess=ProcessRecord{64a3d2f 4887:com.android.deskclock/u0a93}
      stackId=4
      hasBeenVisible=true mResizeMode=RESIZE_MODE_RESIZEABLE_VIA_SDK_VERSION mSupportsPictureInPicture=false isResizeable=true lastActiveTime=223590378 (inactive for 50s)
      * Hist #0: ActivityRecord{ed5f802 u0 com.android.deskclock/.DeskClock t87}
          app=ProcessRecord{64a3d2f 4887:com.android.deskclock/u0a93}
          Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10200000 cmp=com.android.deskclock/.DeskClock bnds=[35,503][237,780] }    
          state=RESUMED stopped=false delayedResume=false finishing=false
    Running activities (most recent first):
      TaskRecord{3a93f6f #87 A=com.android.deskclock U=0 StackId=4 sz=1}
        Run #0: ActivityRecord{ed5f802 u0 com.android.deskclock/.DeskClock t87}
    mResumedActivity: ActivityRecord{ed5f802 u0 com.android.deskclock/.DeskClock t87}
    mLastPausedActivity: ActivityRecord{ed5f802 u0 com.android.deskclock/.DeskClock t87}

  Stack #0: type=home mode=fullscreen
  isSleeping=false
  mBounds=Rect(0, 0 - 0, 0)
    Task id #83
    mBounds=Rect(0, 0 - 0, 0)
    mMinWidth=-1
    mMinHeight=-1
    mLastNonFullscreenBounds=null
    * TaskRecord{6dee666 #83 ?? U=0 StackId=0 sz=1}
      userId=0 effectiveUid=u0a81 mCallingUid=u0a81 mUserSetupComplete=true mCallingPackage=com.android.launcher3
      intent={act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10000100 cmp=com.android.launcher3/.Launcher}
      Activities=[ActivityRecord{3e98fcb u0 com.android.launcher3/.Launcher t83}]
      mRootProcess=ProcessRecord{d9a8f3c 2055:com.android.launcher3/u0a81}
      stackId=0
      hasBeenVisible=true mResizeMode=RESIZE_MODE_RESIZEABLE mSupportsPictureInPicture=false isResizeable=true lastActiveTime=223589976 (inactive for 50s)
      * Hist #0: ActivityRecord{3e98fcb u0 com.android.launcher3/.Launcher t83}        
          app=ProcessRecord{d9a8f3c 2055:com.android.launcher3/u0a81}
          Intent { act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10000100 cmp=com.android.launcher3/.Launcher }
          state=STOPPED stopped=true delayedResume=false finishing=false
    Running activities (most recent first):
      TaskRecord{6dee666 #83 ?? U=0 StackId=0 sz=1}
        Run #0: ActivityRecord{3e98fcb u0 com.android.launcher3/.Launcher t83}
    mLastPausedActivity: ActivityRecord{3e98fcb u0 com.android.launcher3/.Launcher t83}
 ResumedActivity:ActivityRecord{ed5f802 u0 com.android.deskclock/.DeskClock t87}
  ResumedActivity: ActivityRecord{ed5f802 u0 com.android.deskclock/.DeskClock t87}

2.類定義相關(guān)介紹

整體類圖如下：

image.png

2.1 ActivityDisplay

ActivityDisplay 類有如下關(guān)鍵變量

    DisplayContent mDisplayContent;  // 對應(yīng)WindowManagerService的顯示
    /** Actual Display this object tracks. */
    int mDisplayId;  // id

    /**
     * All of the stacks on this display. Order matters, topmost stack is in front of all other
     * stacks, bottommost behind. Accessed directly by ActivityManager package classes. Any calls
     * changing the list should also call {@link #onStackOrderChanged()}.
     */
     // 當(dāng)前顯示屏上的所有ActivityStack
    private final ArrayList<ActivityStack> mStacks = new ArrayList<>();

2.2 ActivityStack

ActivityStack類有如下關(guān)鍵變量

    final int mStackId;  // 唯一ID
    /** The attached Display's unique identifier, or -1 if detached */
    int mDisplayId;  // 所處的顯示屏id,如果detach則為-1
    /**
     * The back history of all previous (and possibly still
     * running) activities.  It contains #TaskRecord objects.
     */
    // ActivityStack里面所包含的所有TaskRecord對象
    private final ArrayList<TaskRecord> mTaskHistory = new ArrayList<>();

    TaskStack mTaskStack;  // 對應(yīng)WindowManagerService里面的

      /**
     * Current activity that is resumed, or null if there is none.
     */
    ActivityRecord mResumedActivity = null; // 當(dāng)前resume狀態(tài)的Activity

2.3 TaskRecord

TaskRecord 類有如下關(guān)鍵變量

    final int taskId;       // Unique identifier for this task.

     /** List of all activities in the task arranged in history order */
    final ArrayList<ActivityRecord> mActivities; // 當(dāng)前Task里面所包含的所有Activity對象

    /** Current stack. Setter must always be used to update the value. */
    private ActivityStack mStack;  // 所屬的ActivityStack

    Task mTask; // 對應(yīng)WindowManagerService里面的

2.4 ActivityRecord

ActivityRecord 類有如下關(guān)鍵變量

   
    final IApplicationToken.Stub appToken; // window manager token
    // TODO: Remove after unification
    AppWindowToken mAppWindowToken; // 繼承自WindowToken,代表一種window類型，為應(yīng)用窗口
    // activity相關(guān)的信息
    final ActivityInfo info; // all about me
    
    private TaskRecord task;        // the task this is in.
    // ActivityRecord在初始化的時候會創(chuàng)建Token對象，作為服務(wù)端
   static class Token extends IApplicationToken.Stub

3.ActivityDisplay/ActivityStack/TaskRecord/ActivityRecord如何關(guān)聯(lián)

詳細(xì)流程可以閱讀Activity 啟動流程log分析

3.1 ActivityRecord創(chuàng)建

在startActivity的過程中，會先new ActivityRecord

08-23 17:30:21.261  1314  4528 V ActivityTaskManager: java.lang.Throwable
08-23 17:30:21.261  1314  4528 V ActivityTaskManager:   at com.android.server.wm.ActivityRecord.setState(ActivityRecord.java:1857)
08-23 17:30:21.261  1314  4528 V ActivityTaskManager:   at com.android.server.wm.ActivityRecord.<init>(ActivityRecord.java:964)
08-23 17:30:21.261  1314  4528 V ActivityTaskManager:   at com.android.server.wm.ActivityStarter.startActivity(ActivityStarter.java:902)

3.2 ActivityStack創(chuàng)建以及和ActivityDisplay的關(guān)聯(lián)

ActivityStack也在是startActivity的過程中創(chuàng)建的

08-23 17:30:21.285  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityStack.<init>(ActivityStack.java:511)
08-23 17:30:21.285  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityDisplay.createStackUnchecked(ActivityDisplay.java:465)
08-23 17:30:21.285  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityDisplay.createStack(ActivityDisplay.java:455)
08-23 17:30:21.285  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityDisplay.getOrCreateStack(ActivityDisplay.java:383)
08-23 17:30:21.285  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityDisplay.getOrCreateStack(ActivityDisplay.java:401)
08-23 17:30:21.285  1314  4528 D ActivityTaskManager:   at com.android.server.wm.RootActivityContainer.getLaunchStack(RootActivityContainer.java:1737)
08-23 17:30:21.285  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityStarter.getLaunchStack(ActivityStarter.java:2704)
08-23 17:30:21.285  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityStarter.computeStackFocus(ActivityStarter.java:2612)
08-23 17:30:21.285  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityStarter.setTaskFromReuseOrCreateNewTask(ActivityStarter.java:2323)
08-23 17:30:21.285  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityStarter.startActivityUnchecked(ActivityStarter.java:1688)
08-23 17:30:21.285  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityStarter.startActivity(ActivityStarter.java:1404)

在ActivityStack的構(gòu)造方法中，會調(diào)用ActivityDisplay的addChild方法，

display.addChild(this, onTop ? POSITION_TOP : POSITION_BOTTOM);

將自己加入到ActivityDisplay的mStack里面，mStack定義如下

ArrayList<ActivityStack> mStacks

此時，ActivityDisplay和ActivityStack關(guān)聯(lián)起來

3.3 TaskRecord創(chuàng)建以及和ActivityStack的關(guān)聯(lián)

TaskRecord也在是startActivity的過程中創(chuàng)建的

08-23 17:30:21.292  1314  4528 D ActivityTaskManager:   at com.android.server.wm.TaskRecord.create(TaskRecord.java:2704)
08-23 17:30:21.292  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityStack.createTaskRecord(ActivityStack.java:5515)
08-23 17:30:21.292  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityStarter.setTaskFromReuseOrCreateNewTask(ActivityStarter.java:2330)
08-23 17:30:21.292  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityStarter.startActivityUnchecked(ActivityStarter.java:1688)

在ActivityStack.createTaskRecord方法里面，調(diào)用addTask將TaskRecord和ActivityStack關(guān)聯(lián)起來

addTask(task, toTop, "createTaskRecord");

將task加入 mTaskHistory，其定義如下

private final ArrayList<TaskRecord> mTaskHistory = new ArrayList<>();

3.4 TaskRecord和ActivityRecord的關(guān)聯(lián)
在3.1 和3.3節(jié)分別創(chuàng)建了ActivityRecord和TaskRecord對象，

08-23 17:30:21.296  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityStarter.addOrReparentStartingActivity(ActivityStarter.java:2574)
08-23 17:30:21.296  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityStarter.setTaskFromReuseOrCreateNewTask(ActivityStarter.java:2335)
08-23 17:30:21.296  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityStarter.startActivityUnchecked(ActivityStarter.java:1688)
08-23 17:30:21.296  1314  4528 D ActivityTaskManager:   at com.android.server.wm.ActivityStarter.startActivity(ActivityStarter.java:1404)

在setTaskFromReuseOrCreateNewTask方法里面，先調(diào)用createTaskRecord來創(chuàng)建TaskRecord，然后調(diào)用addOrReparentStartingActivity來設(shè)置Activity與TaskRecord的關(guān)系

setTaskFromReuseOrCreateNewTask () {
     .....
     final TaskRecord task = mTargetStack.createTaskRecord(
                    mSupervisor.getNextTaskIdForUserLocked(mStartActivity.mUserId),
                    mNewTaskInfo != null ? mNewTaskInfo : mStartActivity.info,
                    mNewTaskIntent != null ? mNewTaskIntent : mIntent, mVoiceSession,
                    mVoiceInteractor, toTop, mStartActivity, mSourceRecord, mOptions);
     addOrReparentStartingActivity(task, "setTaskFromReuseOrCreateNewTask - mReuseTask");
     .....
}

private void addOrReparentStartingActivity(TaskRecord parent, String reason) {
        Slog.d(TAG,"addOrReparentStartingActivity",new Throwable());
        // 如果當(dāng)前ActivityRecord沒有設(shè)置TaskRecord或者已經(jīng)設(shè)置過就是給定的parent,則添加到mActivities列表里面
        if (mStartActivity.getTaskRecord() == null || mStartActivity.getTaskRecord() == parent) {
            parent.addActivityToTop(mStartActivity); // 會調(diào)用r.setTask(this)設(shè)置關(guān)聯(lián)關(guān)系
        } else {
            // 將當(dāng)前要啟動的Activity重新關(guān)聯(lián)到給定的parent 上
            mStartActivity.reparent(parent, parent.mActivities.size() /* top */, reason);
        }
 }

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版權(quán)聲明：本文為CSDN博主「chadm」的原創(chuàng)文章，遵循CC 4.0 BY-SA版權(quán)協(xié)議，轉(zhuǎn)載請附上原文出處鏈接及本聲明。
原文鏈接：https://blog.csdn.net/weixin_42695485/article/details/108680240