使用adb shell dumpsys檢測Android的Activity任務棧

談起Android程序開發,就須要瞭解其四個主要的部件ActivityServiceContentProvider、 BroadcastReceiver。而其中Activity是惟一直接控制程序界面呈現,直面用戶操做的部件(固然BrowadCastReceiver也能經過桌面控件(App Widgets)來呈現有限的操做界面)。Android對於Activity有嚴格的生命週期控制,以限制開發者在適當的回調函數裏的放上合適的代碼。對於多個Activity的轉換,Android也有很是好的管理和流暢的切換,對此Android還引入了任務棧(Task Stack)的概念,這個概念對於Android設備上得返回按鍵有極其重要的聯繫。html

(大部分文檔都將其表述爲Tasks and Back Stack,但從官方文檔的描述來看,Android的相對於Activity講到的Task都視爲一個存放Activities的Stack,因此將其稱爲Task Stack也不爲過。)java

在AndroidManifest中申明所要用到的Activity時能夠設置不一樣的launchMode來獲得不一樣的Activity「啓動」效果。在使用startActivity開啓新的Activity時,傳入的Intent也能夠設置不一樣的Flag來達到不一樣的效果。另外一方面,在Activity啓動時它可能又開啓了另外一個Activity,或者調用了finish()函數終結了Activity。android

這使得Activity棧變得沒法掌握,有時候按下返回按鈕或者點擊關閉當前Activity的操做,都不知道Android系統會把程序帶到那個Activity,不肯定這是不是最後一個Activity以至退出了整個程序。亦或者一些按鈕和操做循環產生Activity而形成內存膨脹。對於這些問題,若是可以在調試期間知道當前任務棧的狀況,就能很方便的觀察和發現問題存在的緣由,進而選擇正確的launchMode,設置恰當IntentFlag來使程序達到預期的效果。shell

 

經過ActivityManager獲取狀態

Android提供了ActivityManger來幫助開發者瞭解運行期間的狀態,經過調用getRunningTasks(int)方法,就能夠在獲得RunningTaskInfo的列表,其表明着當前Android設備正在運行着的Task。從RunningTaskInfo中又能夠進一步獲得更多的信息。bash

  1. ActivityManager am = (ActivityManager)getSystemService(Context.ACTIVITY_SERVICE);
  2. List <RunningTaskInfo> runningTaskInfoList = am.getRunningTasks(10);
  3. for (RunningTaskInfo runningTaskInfo : runningTaskInfoList) {
  4. log ("id: " + runningTaskInfo.id);
  5. log ("description: " + runningTaskInfo.description);
  6. log ("number of activities: " + runningTaskInfo.numActivities);
  7. log ("topActivity: " + runningTaskInfo.topActivity);
  8. log ("baseActivity: " + runningTaskInfo.baseActivity.toString());
  9. }

例如文中提供的示例程序中定義了4個具備不一樣launchMode的Activity,每點擊一次菜單欄上得選項就會彈出一個新的Activity(或者將指定Singleton的Activity置前)。
task-stack-demo
Activity上顯示的數字則指示startActivity()被第幾回調用時開啓了這個Activity。有一些Singleton的會顯示多個數字,也代表它是被複用的。
task-stack-single-top
由於在onCreate()方法上放置了上述代碼,因此觀察log就能發現當前有多少個Task在被執行,每一個Task又有多少個Activities。app

D/IDER    ( 3700): =====================
D/IDER    ( 3700): ---------------------
D/IDER    ( 3700): id: 25
D/IDER    ( 3700): description: null
D/IDER    ( 3700): number of activities: 4
D/IDER    ( 3700): topActivity: ComponentInfo{com.iderzheng/com.iderzheng.StandardActivity}
D/IDER    ( 3700): baseActivity: ComponentInfo{com.iderzheng/com.iderzheng.SingleTaskActivity}
D/IDER    ( 3700): ---------------------
D/IDER    ( 3700): id: 24
D/IDER    ( 3700): description: null
D/IDER    ( 3700): number of activities: 1
D/IDER    ( 3700): topActivity: ComponentInfo{com.iderzheng/com.iderzheng.SingleInstanceActivity}
D/IDER    ( 3700): baseActivity: ComponentInfo{com.iderzheng/com.iderzheng.SingleInstanceActivity}
D/IDER    ( 3700): ---------------------
D/IDER    ( 3700): id: 23
D/IDER    ( 3700): description: null
D/IDER    ( 3700): number of activities: 2
D/IDER    ( 3700): topActivity: ComponentInfo{com.iderzheng/com.iderzheng.StandardActivity}
D/IDER    ( 3700): baseActivity: ComponentInfo{com.iderzheng/com.iderzheng.MainActivity}
D/IDER    ( 3700): ---------------------
D/IDER    ( 3700): id: 1
D/IDER    ( 3700): description: null
D/IDER    ( 3700): number of activities: 1
D/IDER    ( 3700): topActivity: ComponentInfo{com.android.launcher/com.android.launcher2.Launcher}
D/IDER    ( 3700): baseActivity: ComponentInfo{com.android.launcher/com.android.launcher2.Launcher}

缺點

必須在程序中注入調試代碼,由於要控制在發佈時代碼必須被清理了。RunningTaskInfo雖然可以告訴咱們有多少個Activity保存在其上,可是沒有提供完整的列表,只能看到頭尾兩個Activity。給出的兩個Activity的屬性:topActivity和baseActivity也只是ComponentName類型,並不是真實的Activity對象,所以除了類的名字沒有其餘更多信息。ide

手動記錄和管理Activities棧

Activity的建立和銷燬都會有相應的回調函數:onCreate()onDestroy()。所以能夠自建一個靜態全局Stack對象,在onCreate()時候講當前Activity對象加入到Stack中,而在onDestroy()時把它從Stack中移除。這樣咱們就隨時能夠知道當前Activity的詳細狀況了。wordpress

缺點

要讓全部Activity的onCreate()onDestroy()方法上有對應的進出棧的方法,要麼有統一的基類,要麼強制每一個Activity都加入這些代碼,但兩種方式都不完美。另外也很難模擬singleTask這類會建立出新的Task的狀況,這時光使用一個Stack就不足夠了,要考慮全部的狀況又不太可能。再者如同使用ActivityManager同樣這些代碼也應該只出如今調試階段函數

使用adb shell指令

Android還爲開發者提供了adb(Android Debug Bridge),這是很是強大的調試工具。最經常使用的天然是logcat來顯示日誌記錄。另一個很強大的指令就是這裏要提到的dumpsysdumpsys還能夠添加不一樣的參數來指示須要輸出哪一類Service的信息。對於本文提到的內容,須要查看的就是activity,指令就是:工具

adb shell dumpsys activity


輸入上述指令,就能獲得關於設備很是長的一段訊息,單是也能清晰看出它們比較詳細的分類

 

ACTIVITY MANAGER PENDING INTENTS (dumpsys activity intents)
  * PendingIntentRecord{42b05f20 com.android.vending startService}
  ... ... ... ...

ACTIVITY MANAGER BROADCAST STATE (dumpsys activity broadcasts)
  Historical broadcasts [foreground]:
  #0: BroadcastRecord{430d2fb8 u-1 android.intent.action.TIME_TICK}
    act=android.intent.action.TIME_TICK flg=0x50000014 (has extras)
    extras: Bundle[{android.intent.extra.ALARM_COUNT=1}]
  ... ... ... ...

ACTIVITY MANAGER CONTENT PROVIDERS (dumpsys activity providers)
  Published single-user content providers (by class):
  * ContentProviderRecord{429d18a8 u0 com.android.phone/.IccProvider}
    proc=ProcessRecord{429765d8 858:com.android.phone/1001}
    singleton=true
    authority=icc
  ... ... ... ...

ACTIVITY MANAGER SERVICES (dumpsys activity services)
  User 0 active services:
  * ServiceRecord{429f8668 u0 com.android.bluetooth/.hid.HidService}
    app=null
    created=-1h44m27s317ms started=false connections=0
  ... ... ... ...

ACTIVITY MANAGER ACTIVITIES (dumpsys activity activities)
  Stack #0:
    Task id #28
      TaskRecord{43525058 #28 A=com.android.systemui U=0 sz=1}
      Intent { act=com.android.systemui.recent.action.TOGGLE_RECENTS flg=0x10c00000 cmp=com.android.systemui/.recent.RecentsActivity (has extras) }
        Hist #0: ActivityRecord{428d1ae8 u0 com.android.systemui/.recent.RecentsActivity t28}
          Intent { act=com.android.systemui.recent.action.TOGGLE_RECENTS flg=0x10800000 cmp=com.android.systemui/.recent.RecentsActivity bnds=[328,886][656,1176] }
          ProcessRecord{42968230 695:com.android.systemui/u0a12}
  ... ... ... ...

ACTIVITY MANAGER RUNNING PROCESSES (dumpsys activity processes)
  Process LRU list (sorted by oom_adj, 28 total, non-act at 3, non-svc at 3):
    PERS #27: sys   F/ /P  trm: 0 605:system/1000 (fixed)
  ... ... ... ...

每個類別都有一個括號內容,給出了更加詳細的指令來查看該類別下更多具體內容。所以再來嘗試指令:

db shell dumpsys activity activities

就能看到下邊的結果

CTIVITY MANAGER ACTIVITIES (dumpsys activity activities)
  Stack #0:
    Task id #28
    * TaskRecord{43525058 #28 A=com.android.systemui U=0 sz=1}
      ... ... ... ...
      * Hist #0: ActivityRecord{428d1ae8 u0 com.android.systemui/.recent.RecentsActivity t28}
          ... ... ... ...
    Task id #1
    * TaskRecord{429a35f8 #1 A=com.android.launcher U=0 sz=1}
      ... ... ... ...
      * Hist #0: ActivityRecord{429a1760 u0 com.android.launcher/com.android.launcher2.Launcher t1}
          ... ... ... ...

    Running activities (most recent first):
      TaskRecord{43525058 #28 A=com.android.systemui U=0 sz=1}
        Run #1: ActivityRecord{428d1ae8 u0 com.android.systemui/.recent.RecentsActivity t28}
      TaskRecord{429a35f8 #1 A=com.android.launcher U=0 sz=1}
        Run #0: ActivityRecord{429a1760 u0 com.android.launcher/com.android.launcher2.Launcher t1}

    mLastPausedActivity: ActivityRecord{428d1ae8 u0 com.android.systemui/.recent.RecentsActivity t28}

  Stack #1:
    Task id #25
    * TaskRecord{42b0ee20 #25 I=com.iderzheng/.SingleTaskActivity U=0 sz=5}
      numActivities=5 rootWasReset=false userId=0 mTaskType=0 numFullscreen=5 mOnTopOfHome=true
      intent={cmp=com.iderzheng/.SingleTaskActivity}
      realActivity=com.iderzheng/.SingleTaskActivity
      Activities=[ActivityRecord{42a7e160 u0 com.iderzheng/.SingleTaskActivity t25}, ActivityRecord{42bffdf0 u0 com.iderzheng/.StandardActivity t25}, ActivityRecord{42e9e8f8 u0 com.iderzheng/.SingleTopActivity t25}, ActivityRecord{434c2238 u0 com.iderzheng/.StandardActivity t25}, ActivityRecord{4279d2d8 u0 com.iderzheng/.SingleTopActivity t25}]
      askedCompatMode=false
      lastThumbnail=null lastDescription=null
      lastActiveTime=6229735 (inactive for 357s)
      * Hist #4: ActivityRecord{4279d2d8 u0 com.iderzheng/.SingleTopActivity t25}
          packageName=com.iderzheng processName=com.iderzheng
          launchedFromUid=10124 launchedFromPackage=com.iderzheng userId=0
          app=ProcessRecord{4312cbb0 3700:com.iderzheng/u0a124}
          Intent { cmp=com.iderzheng/.SingleTopActivity bnds=[328,580][656,870] }
          frontOfTask=false task=TaskRecord{42b0ee20 #25 I=com.iderzheng/.SingleTaskActivity U=0 sz=5}
          taskAffinity=com.iderzheng
          realActivity=com.iderzheng/.SingleTopActivity
          baseDir=/data/app/com.iderzheng-1.apk
          dataDir=/data/data/com.iderzheng
          stateNotNeeded=false componentSpecified=true mActivityType=0
          compat={320dpi} labelRes=0x7f0a0013 icon=0x7f020057 theme=0x7f0b0000
          config={1.0 310mcc?mnc en_US ldltr sw384dp w384dp h567dp 320dpi nrml port finger -keyb/v/h -nav/h s.7}
          launchFailed=false launchCount=0 lastLaunchTime=-1h40m33s397ms
          haveState=false icicle=null
          state=RESUMED stopped=false delayedResume=false finishing=false
          keysPaused=false inHistory=true visible=true sleeping=false idle=true
          fullscreen=true noDisplay=false immersive=false launchMode=1
          frozenBeforeDestroy=false thumbnailNeeded=false forceNewConfig=false
          mActivityType=APPLICATION_ACTIVITY_TYPE
          thumbHolder: 42b0ee20 bm=null desc=null
          waitingVisible=false nowVisible=true lastVisibleTime=-5m56s862ms
    ... ... ... ...

    Running activities (most recent first):
      TaskRecord{42b0ee20 #25 I=com.iderzheng/.SingleTaskActivity U=0 sz=5}
        Run #7: ActivityRecord{4279d2d8 u0 com.iderzheng/.SingleTopActivity t25}
      TaskRecord{429e9558 #24 A=com.iderzheng U=0 sz=1}
        Run #6: ActivityRecord{429d5408 u0 com.iderzheng/.SingleInstanceActivity t24}
      TaskRecord{42b0ee20 #25 I=com.iderzheng/.SingleTaskActivity U=0 sz=5}
        Run #5: ActivityRecord{434c2238 u0 com.iderzheng/.StandardActivity t25}
        Run #4: ActivityRecord{42e9e8f8 u0 com.iderzheng/.SingleTopActivity t25}
        Run #3: ActivityRecord{42bffdf0 u0 com.iderzheng/.StandardActivity t25}
        Run #2: ActivityRecord{42a7e160 u0 com.iderzheng/.SingleTaskActivity t25}
      TaskRecord{4282e508 #23 A=com.iderzheng U=0 sz=2}
        Run #1: ActivityRecord{429655d8 u0 com.iderzheng/.StandardActivity t23}
        Run #0: ActivityRecord{429564e0 u0 com.iderzheng/.MainActivity t23}
 
  ... ... ... ...

  Recent tasks:
  ... ... ... ...

整個log顯示了當前全部在運行的任務棧,它們的id分別是什麼。對於每一個Task,也有Activity數量等信息,同時也列出了其中的Activity列表,而且對於每一個Activity也有比較詳細的描述,好比啓動它的Intent的內容。

若是以爲內容過多,只想看看棧的內容,也能夠直接跳到」Running activities (most recent first)」那部分,比較簡潔而又明瞭的列出了棧中得Activity列表,就能知道當按下返回鍵的時候會應該會回到哪一個Activity之後是要退出程序。

對於」Running activitie」s的內容在dumpsys activity中就有,並不須要dumpsys activity activities,也能夠用下邊的指令來限制僅輸出」Running activities」列表:

adb shell dumpsys activity activities | sed -En -e '/Running activities/,/Run #0/p'

缺點

很明顯的看出,使用adb shell的相對於以前的方式的明顯好處就是不須要添加額外的代碼,並且任務棧的信息也更加詳盡。可是一樣的它只能輸出Activity的類名,對於具體屬性沒有記錄。

 

adb shell對於調試Android程序有不少的幫助,惋惜對於adb指令都沒有比較全面詳細而又系統的教程。只能靠在實踐中慢慢摸索,從網上零星介紹中得到。

Download Source Code for Testing

References:
  1. Android Debug Bridge | Android Developers
  2. How to know which activities are running in Android | The skiing cube
  3. Wrightrocket: Using dumpsys commands in the Android adb shell
  4. activity – How to find back stack activities in an android application? – Stack Overflow
  5. What’s Android ADB shell ‘dumpsys’ tool and it’s benefits? – Stack Overflow
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