oynix

于无声处听惊雷，于无色处见繁花

Android基础之singleTask

发表于 分类于 本文字数： 16k 阅读时长 ≈ 15 分钟

时间做的久了，基础的知识忘的越来越多，正所谓：基础不牢，地动山摇。最近有需要，所以在慢慢重来，今天说一说Activity的几种启动模式。

前言

启动模式有4种：standard、singleTop、singleTask和singleInstance，这次主要说一说singleTask，相比于其他，这个算是比较复杂一些的。

利用adb提供的命令adb shell dumpsys activity activities可以查看设备当前的activity栈信息。此外，adb shell dumpsys可以查看各种信息，直接输入就会列出它所支持的所有服务。

下面贴了一段我用的测试设备的activity信息，乍一看上去内容有些冗杂，其实是因为里面包含了很详细的信息和关系，从头按行读，读懂的话不是问题。从这些数据中，可以对Process、Task之间的关系有个大致了解。

为了不影响阅读体验，我把它折叠起来了。

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

  Stack #7: type=standard mode=fullscreen
  isSleeping=false
  mBounds=Rect(0, 0 - 0, 0)
    Task id #25
    mBounds=Rect(0, 0 - 0, 0)
    mMinWidth=-1
    mMinHeight=-1
    mLastNonFullscreenBounds=null
    * TaskRecord{3e1780c #25 A=com.oynix.launch.mode.sample U=0 StackId=7 sz=2}
      userId=0 effectiveUid=u0a208 mCallingUid=2000 mUserSetupComplete=true mCallingPackage=null
      affinity=com.oynix.launch.mode.sample
      intent={act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.oynix.launch.mode.sample/.MainActivity}
      realActivity=com.oynix.launch.mode.sample/.MainActivity
      autoRemoveRecents=false isPersistable=true numFullscreen=2 activityType=1
      rootWasReset=false mNeverRelinquishIdentity=true mReuseTask=false mLockTaskAuth=LOCK_TASK_AUTH_PINNABLE
      Activities=[ActivityRecord{a1dcebd u0 com.oynix.launch.mode.sample/.MainActivity t25}, ActivityRecord{907f0e u0 com.oynix.launch.mode.sample/.AActivity t25}]
      askedCompatMode=false inRecents=true isAvailable=true
      mRootProcess=ProcessRecord{26080b8d0 21734:com.oynix.launch.mode.sample/u0a208}
      stackId=7
      hasBeenVisible=true mResizeMode=RESIZE_MODE_RESIZEABLE_VIA_SDK_VERSION mSupportsPictureInPicture=false isResizeable=true lastActiveTime=6697777 (inactive for 3s)
      isLaunchedPairApp=false
      mOverrideConfig={0.0 ?mcc?mnc ?localeList ?layoutDir ?swdp ?wdp ?hdp ?density ?lsize ?long ?ldr ?wideColorGamut ?orien ?uimode ?night ?touch ?keyb/?/? ?nav/? winConfig={ mBounds=Rect(0, 0 - 0, 0) mAppBounds=null mWindowingMode=undefined mActivityType=undefined} mkbd/? desktop/?showBtnShape = -1  themeSeq=0 0 0  ?dc}
      dexBoundsPolicy:
       mLastNonFullBoundsDisplayId=-1
      * Hist #1: ActivityRecord{907f0e u0 com.oynix.launch.mode.sample/.AActivity t25}
          packageName=com.oynix.launch.mode.sample processName=com.oynix.launch.mode.sample
          launchedFromUid=10208 launchedFromPackage=com.oynix.launch.mode.sample userId=0
          app=ProcessRecord{26080b8d0 21734:com.oynix.launch.mode.sample/u0a208}
          Intent { cmp=com.oynix.launch.mode.sample/.AActivity }
          frontOfTask=false task=TaskRecord{3e1780c #25 A=com.oynix.launch.mode.sample U=0 StackId=7 sz=2}
          taskAffinity=com.oynix.launch.mode.sample
          realActivity=com.oynix.launch.mode.sample/.AActivity
          baseDir=/data/app/com.oynix.launch.mode.sample-3DMFUnGXrp7XpBKiFV3-Tg==/base.apk
          dataDir=/data/user/0/com.oynix.launch.mode.sample
          stateNotNeeded=false componentSpecified=true mActivityType=standard
          compat={480dpi} labelRes=0x7f0e001b icon=0x7f0c0000 theme=0x7f0f01a1
          mLastReportedConfigurations:
           mGlobalConfig={0.9 ?mcc?mnc [zh_CN_#Hans] ldltr sw360dp w360dp h668dp 480dpi nrml long port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 0, 0) mAppBounds=Rect(0, 0 - 1080, 2076) mWindowingMode=fullscreen mActivityType=undefined} s.9 mkbd/h desktop/dshowBtnShape = 0  themeSeq=0 0 0  ?dc}
           mOverrideConfig={0.9 ?mcc?mnc [zh_CN_#Hans] ldltr sw360dp w360dp h668dp 480dpi nrml long port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1080, 2076) mAppBounds=Rect(0, 0 - 1080, 2076) mWindowingMode=fullscreen mActivityType=standard} s.9 mkbd/h desktop/dshowBtnShape = 0  themeSeq=0 0 0  ?dc}
          CurrentConfiguration={0.9 ?mcc?mnc [zh_CN_#Hans] ldltr sw360dp w360dp h668dp 480dpi nrml long port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1080, 2076) mAppBounds=Rect(0, 0 - 1080, 2076) mWindowingMode=fullscreen mActivityType=standard} s.9 mkbd/h desktop/dshowBtnShape = 0  themeSeq=0 0 0  ?dc}
          taskDescription: label="null" icon=null iconResource=0 iconFilename=null primaryColor=ff6200ee
           backgroundColor=ffffffff
           statusBarColor=ff3700b3
           navigationBarColor=fff2f2f2
          launchFailed=false launchCount=1 lastLaunchTime=-5s311ms
          haveState=false icicle=null
          state=RESUMED stopped=false delayedResume=false finishing=false
          keysPaused=false inHistory=true visible=true sleeping=false idle=true mStartingWindowState=STARTING_WINDOW_NOT_SHOWN
          fullscreen=true noDisplay=false immersive=false launchMode=0
          frozenBeforeDestroy=false forceNewConfig=false
          mActivityType=standard
          vrActivityType=0
          waitingVisible=false nowVisible=true lastVisibleTime=-4s856ms
          resizeMode=RESIZE_MODE_RESIZEABLE_VIA_SDK_VERSION
          mLastReportedMultiWindowMode=false mLastReportedPictureInPictureMode=false
          mUseDeviceDefaultTheme=false
      * Hist #0: ActivityRecord{a1dcebd u0 com.oynix.launch.mode.sample/.MainActivity t25}
          packageName=com.oynix.launch.mode.sample processName=com.oynix.launch.mode.sample
          launchedFromUid=2000 launchedFromPackage=null userId=0
          app=ProcessRecord{26080b8d0 21734:com.oynix.launch.mode.sample/u0a208}
          Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.oynix.launch.mode.sample/.MainActivity }
          frontOfTask=true task=TaskRecord{3e1780c #25 A=com.oynix.launch.mode.sample U=0 StackId=7 sz=2}
          taskAffinity=com.oynix.launch.mode.sample
          realActivity=com.oynix.launch.mode.sample/.MainActivity
          baseDir=/data/app/com.oynix.launch.mode.sample-3DMFUnGXrp7XpBKiFV3-Tg==/base.apk
          dataDir=/data/user/0/com.oynix.launch.mode.sample
          stateNotNeeded=false componentSpecified=true mActivityType=standard
          compat={480dpi} labelRes=0x7f0e001b icon=0x7f0c0000 theme=0x7f0f01a1
          mLastReportedConfigurations:
           mGlobalConfig={0.9 ?mcc?mnc [zh_CN_#Hans] ldltr sw360dp w360dp h668dp 480dpi nrml long port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 0, 0) mAppBounds=Rect(0, 0 - 1080, 2076) mWindowingMode=fullscreen mActivityType=undefined} s.9 mkbd/h desktop/dshowBtnShape = 0  themeSeq=0 0 0  ?dc}
           mOverrideConfig={0.9 ?mcc?mnc [zh_CN_#Hans] ldltr sw360dp w360dp h668dp 480dpi nrml long port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1080, 2076) mAppBounds=Rect(0, 0 - 1080, 2076) mWindowingMode=fullscreen mActivityType=standard} s.9 mkbd/h desktop/dshowBtnShape = 0  themeSeq=0 0 0  ?dc}
          CurrentConfiguration={0.9 ?mcc?mnc [zh_CN_#Hans] ldltr sw360dp w360dp h668dp 480dpi nrml long port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1080, 2076) mAppBounds=Rect(0, 0 - 1080, 2076) mWindowingMode=fullscreen mActivityType=standard} s.9 mkbd/h desktop/dshowBtnShape = 0  themeSeq=0 0 0  ?dc}
          taskDescription: label="null" icon=null iconResource=0 iconFilename=null primaryColor=ff6200ee
           backgroundColor=ffffffff
           statusBarColor=ff3700b3
           navigationBarColor=fff2f2f2
          launchFailed=false launchCount=0 lastLaunchTime=-24s316ms
          haveState=true icicle=Bundle[mParcelledData.dataSize=2448]
          state=STOPPED stopped=true delayedResume=false finishing=false
          keysPaused=false inHistory=true visible=false sleeping=false idle=true mStartingWindowState=STARTING_WINDOW_REMOVED
          fullscreen=true noDisplay=false immersive=false launchMode=0
          frozenBeforeDestroy=false forceNewConfig=false
          mActivityType=standard
          vrActivityType=0
          waitingVisible=false nowVisible=false lastVisibleTime=-6s410ms
          resizeMode=RESIZE_MODE_RESIZEABLE_VIA_SDK_VERSION
          mLastReportedMultiWindowMode=false mLastReportedPictureInPictureMode=false
          mUseDeviceDefaultTheme=false

    Running activities (most recent first):
      TaskRecord{3e1780c #25 A=com.oynix.launch.mode.sample U=0 StackId=7 sz=2}
        Run #1: ActivityRecord{907f0e u0 com.oynix.launch.mode.sample/.AActivity t25}
        Run #0: ActivityRecord{a1dcebd u0 com.oynix.launch.mode.sample/.MainActivity t25}

    mResumedActivity: ActivityRecord{907f0e u0 com.oynix.launch.mode.sample/.AActivity t25}
    mLastPausedActivity: ActivityRecord{a1dcebd u0 com.oynix.launch.mode.sample/.MainActivity t25}

  Stack #0: type=home mode=fullscreen
  isSleeping=false
  mBounds=Rect(0, 0 - 0, 0)

    Task id #18
    mBounds=Rect(0, 0 - 0, 0)
    mMinWidth=-1
    mMinHeight=-1
    mLastNonFullscreenBounds=null
    * TaskRecord{13181bb #18 I=com.sec.android.app.launcher/com.android.launcher3.infra.activity.Launcher U=0 StackId=0 sz=1}
      userId=0 effectiveUid=u0a96 mCallingUid=1000 mUserSetupComplete=true mCallingPackage=android
      intent={act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10800100 cmp=com.sec.android.app.launcher/com.android.launcher3.infra.activity.Launcher}
      origActivity=com.sec.android.app.launcher/.activities.LauncherActivity
      realActivity=com.sec.android.app.launcher/com.android.launcher3.infra.activity.Launcher
      autoRemoveRecents=false isPersistable=false numFullscreen=1 activityType=2
      rootWasReset=false mNeverRelinquishIdentity=true mReuseTask=false mLockTaskAuth=LOCK_TASK_AUTH_PINNABLE
      Activities=[ActivityRecord{ad01979 u0 com.sec.android.app.launcher/.activities.LauncherActivity t18}]
      askedCompatMode=false inRecents=true isAvailable=true
      stackId=0
      hasBeenVisible=true mResizeMode=RESIZE_MODE_RESIZEABLE mSupportsPictureInPicture=false isResizeable=true lastActiveTime=6676345 (inactive for 24s)
      isLaunchedPairApp=false
      mOverrideConfig={0.0 ?mcc?mnc ?localeList ?layoutDir ?swdp ?wdp ?hdp ?density ?lsize ?long ?ldr ?wideColorGamut ?orien ?uimode ?night ?touch ?keyb/?/? ?nav/? winConfig={ mBounds=Rect(0, 0 - 0, 0) mAppBounds=null mWindowingMode=undefined mActivityType=undefined} mkbd/? desktop/?showBtnShape = -1  themeSeq=0 0 0  ?dc}
      dexBoundsPolicy:
       mLastNonFullBoundsDisplayId=-1
      * Hist #0: ActivityRecord{ad01979 u0 com.sec.android.app.launcher/.activities.LauncherActivity t18}
          packageName=com.sec.android.app.launcher processName=com.sec.android.app.launcher
          launchedFromUid=0 launchedFromPackage=null userId=0
          app=ProcessRecord{95a823d0 5418:com.sec.android.app.launcher/u0a96}
          Intent { act=android.intent.action.MAIN cat=[android.intent.category.HOME] flg=0x10800100 cmp=com.sec.android.app.launcher/.activities.LauncherActivity }
          frontOfTask=true task=TaskRecord{13181bb #18 I=com.sec.android.app.launcher/com.android.launcher3.infra.activity.Launcher U=0 StackId=0 sz=1}
          taskAffinity=null
          realActivity=com.sec.android.app.launcher/com.android.launcher3.infra.activity.Launcher
          baseDir=/system/priv-app/TouchWizHome_2017/TouchWizHome_2017.apk
          dataDir=/data/user/0/com.sec.android.app.launcher
          stateNotNeeded=true componentSpecified=false mActivityType=home
          compat={480dpi} labelRes=0x7f090042 icon=0x7f020127 theme=0x7f0e019c
          mLastReportedConfigurations:
           mGlobalConfig={0.9 ?mcc?mnc [zh_CN_#Hans] ldltr sw360dp w360dp h668dp 480dpi nrml long port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 0, 0) mAppBounds=Rect(0, 0 - 1080, 2076) mWindowingMode=fullscreen mActivityType=undefined} s.9 mkbd/h desktop/dshowBtnShape = 0  themeSeq=0 0 0  ?dc}
           mOverrideConfig={0.9 ?mcc?mnc [zh_CN_#Hans] ldltr sw360dp w360dp h668dp 480dpi nrml long port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1080, 2076) mAppBounds=Rect(0, 0 - 1080, 2076) mWindowingMode=fullscreen mActivityType=home} s.9 mkbd/h desktop/dshowBtnShape = 0  themeSeq=0 0 0  ?dc}
          CurrentConfiguration={0.9 ?mcc?mnc [zh_CN_#Hans] ldltr sw360dp w360dp h668dp 480dpi nrml long port finger -keyb/v/h -nav/h winConfig={ mBounds=Rect(0, 0 - 1080, 2076) mAppBounds=Rect(0, 0 - 1080, 2076) mWindowingMode=fullscreen mActivityType=home} s.9 mkbd/h desktop/dshowBtnShape = 0  themeSeq=0 0 0  ?dc}
          OverrideConfiguration={0.0 ?mcc?mnc ?localeList ?layoutDir ?swdp ?wdp ?hdp ?density ?lsize ?long ?ldr ?wideColorGamut ?orien ?uimode ?night ?touch ?keyb/?/? ?nav/? winConfig={ mBounds=Rect(0, 0 - 0, 0) mAppBounds=null mWindowingMode=undefined mActivityType=home} mkbd/? desktop/?showBtnShape = -1  themeSeq=0 0 0  ?dc}
          taskDescription: label="null" icon=null iconResource=0 iconFilename=null primaryColor=ff0074d4
           backgroundColor=fffafafa
           statusBarColor=0
           navigationBarColor=0
          launchFailed=false launchCount=0 lastLaunchTime=-1h51m21s986ms
          haveState=true icicle=Bundle[mParcelledData.dataSize=14056]
          state=STOPPED stopped=true delayedResume=false finishing=false
          keysPaused=false inHistory=true visible=false sleeping=false idle=true mStartingWindowState=STARTING_WINDOW_NOT_SHOWN
          fullscreen=true noDisplay=false immersive=false launchMode=2
          frozenBeforeDestroy=false forceNewConfig=false
          mActivityType=home
          vrActivityType=0
          waitingVisible=false nowVisible=false lastVisibleTime=-1m33s752ms
          connections=[ConnectionRecord{108b50e u0 CR com.samsung.android.app.spage/.service.overlay.PageOverlayService:@e38ef09}]
          resizeMode=RESIZE_MODE_RESIZEABLE
          mLastReportedMultiWindowMode=false mLastReportedPictureInPictureMode=false
          mUseDeviceDefaultTheme=true

    Running activities (most recent first):
      TaskRecord{13181bb #18 I=com.sec.android.app.launcher/com.android.launcher3.infra.activity.Launcher U=0 StackId=0 sz=1}
        Run #0: ActivityRecord{ad01979 u0 com.sec.android.app.launcher/.activities.LauncherActivity t18}

    mLastPausedActivity: ActivityRecord{ad01979 u0 com.sec.android.app.launcher/.activities.LauncherActivity t18}

  ResumedActivity: ActivityRecord{907f0e u0 com.oynix.launch.mode.sample/.AActivity t25}
  mFocusedStack=ActivityStack{9f0e91 stackId=7 type=standard mode=fullscreen visible=true translucent=false, 1 tasks} mLastFocusedStack=ActivityStack{9f0e91 stackId=7 type=standard mode=fullscreen visible=true translucent=false, 1 tasks}
  mCurTaskIdForUser={0=25}
  mUserStackInFront={}
  displayId=0 stacks=2
   mHomeStack=ActivityStack{364f85f stackId=0 type=home mode=fullscreen visible=false translucent=true, 1 tasks}
   mDefaultMinSizeOfResizeableTask=660
  isHomeRecentsComponent=true  mDefaultMinSizeOfResizeableTask=660  KeyguardController:
    mKeyguardShowing=false
    mAodShowing=false
    mKeyguardGoingAway=true
    mOccluded=false
    mDismissingKeyguardActivity=null
    mDismissalRequested=false
    mVisibilityTransactionDepth=0
    mDexOccluded=false
    mDexDisplaySleepToken=null
  LockTaskController
    mLockTaskModeState=NONE
    mLockTaskModeTasks=
    mLockTaskPackages (userId:packages)=
      u0:[]

几个概念

在此之前，做一些准备工作，有几个名词需要先解释。

  • Process 进程
    如果没有特殊的配置，启动一个application就会启动一个进程，进程名称默认为包名。进程之间相互独立，内存互不共享。一个进程内可以有多个线程，这些线程的内存是共享的，所以一个变量可以同时被多个线程访问，从而导致的线程不安全问题。
    在AndroidManifest.xml文件中声明四大组件时，如果设置了android:process属性，这个就不会运行在applicaton的所在的进程，而是另起一个新的进程。进程的名字就是android:process属性的值。

  • Task 任务
    可以简单的把Task理解成一个存放Activity的栈，一个Activity必须依附于一个Task，启动Activity就是将Activity实例压入栈顶，销毁Activity就是将Activity实例出栈的过程。Activity虽然依附于Task，但并不是随便一个Task就可以，每个Task都有一个name，Activity就是根据这个名字找到自己的归宿。意思就是说，会同时存在多个Task，从上面dumpsys的结果也可以看出这一点，其中的TaskRecord便是一个Task实例。Task的名字是可以重复的，这与其中包含的Activity的模式有关，下面再说。

  • android:taskAffinity
    这是AndroidManifest.xml文件中，activity标签的一个属性，字符串类型。affinity，直译过来就是密切关系、类同的意思，在这里就是指定Task的名字。application也有这个属性，当activity不设置这个属性时，默认会使用application这个属性的值；如果application也没有设置这个属性的值，那就默认使用包名。所以，不设置这个属性时，activity启动后都会依附在一个名字为包名的Task中，从dumpsys结果也可以看出来。

模式：standard

这个是默认的模式，不主动设置的Activity，都是这个模式。这个模式很好理解，只要设置成这个模式，它从生到死都会存在包名为名称的Task中，即便是设置了taskAffinify也不会生效。每次启动，都会创建新的实例压入Task的栈顶。

模式：singleTop

从名字来看，就是单独的顶部。意思就是，在Task栈顶只会有一个实例。启动时，如果发现栈顶就是这个activity的实例，那么就会通过重用这个实例，这个时候会掉用Activity中的onNewIntent方法。这个模式也对taskAffinify属性无效，只会存在于包名的Task中。常用于内容详情，如新闻详情，单独占一个页面，浏览完详情，底部会显示几个其他新闻的链接，点击之后，会再次启动新闻详情，自己跳自己，这样不管跳转了多少次，按一次返回，就可以回到新闻列表页面。

模式：singleTask

如果上面解释的几个概念都能明白，那这个属性就很好说了。顾名思义，在Task中只会存在一个实例。这个模式下，taskAnffinity属性会生效，如果不设置，那就是包名。启动Activity时，首先会按照taskAnffinity查找对应的Task，如果没找到，那么就新建一个，然后将Activity实例压入栈；如果找到了该名字的Task，那么会在该Task中查找Activity的实例，若找到，如果不在Task栈顶，那么就将上面的Activity实例全部出栈，使其位于栈顶；如果栈中无此Activity的实例，则新建实例并压入栈。

模式：singleInstance

这个也很好理解，凡是以这个模式启动的Activity，都会自己独占一个Task。如果不存在则创建新Task然后实例压入栈，如果存在则onNewIntent复用其中的Activity实例。如果不设置taskAffinity，那么Task的名字就是包名，这时，就会有两个名字都是包名的Task，所以Task的名字是可能会相同的。这里强调一下独占这个词，如果一个以singleTask启动的Activity，找到了它目标名字的Task，但是这个Task里包含singleInstance启动的Activity实例，那么它会将实例压入该栈吗？不会的，因为是独占，所以不允许其他实例。

总结

其中3个都很好理解，standard是默认模式，只要启动就会创建新实例并压入默认Task；singleTop是栈顶存在就复用，不存在就创建；singleInstance是独占一个Task；singleTask是先找到目标名字、且没有被独占的Task，找不到则新建，Task中若存在实例则通过弹出上面的实例使其处于栈顶并onNewIntent复用，已在栈顶则直接复用，若Task栈中不存在实例，则创建并压入栈。

如果能自己把每个模式验证，那么理解的就会深刻些。我便是跑了一个Application，写了几个简单的Activity，通过不断调整AndroidManifest.xml中Activity的launchMode和taskAnffinity，然后配合adb shell dumpsys activity activities命令，从头到尾走了一遍。

附上Git地址：https://github.com/oynix/launch-mode-sample

------------- (完) -------------
  • 本文作者： oynix
  • 本文链接： https://oynix.com/2021/08/765699b0dec3/
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