Android系統(tǒng)默認(rèn)Home應(yīng)用程序(Launcher)的啟動(dòng)過程源代碼分析

1、在前面一篇文章中，我們分析了Android系統(tǒng)在啟動(dòng)時(shí)安裝應(yīng)用程序的過程，這些應(yīng)用程序安裝好之后，還需要有一個(gè)Home應(yīng)用程序來負(fù)責(zé)把它們?cè)谧烂嫔险故境鰜?，在Android系統(tǒng)中，這個(gè)默認(rèn)的Home應(yīng)用程序就是Launcher了，本文將詳細(xì)分析Launcher應(yīng)用程序的啟動(dòng)過程。Android系統(tǒng)的Home應(yīng)用程序Launcher是由ActivityManagerService啟動(dòng)的，而ActivityManagerService和PackageManagerService一樣，都是在開機(jī)時(shí)由SystemServer組件啟動(dòng)的，SystemServer組件首先是啟動(dòng)ePackageManage

2、rServic,由它來負(fù)責(zé)安裝系統(tǒng)的應(yīng)用程序，具體可以參考前面一篇文章Android應(yīng)用程序安裝過程源代碼分析,系統(tǒng)中的應(yīng)用程序安裝好了以后，SystemServer組件接下來就要通過ActivityManagerService來啟動(dòng)Home應(yīng)用程序Launcher了，Launcher在啟動(dòng)的時(shí)候便會(huì)通過PackageManagerServic把系統(tǒng)中已經(jīng)安裝好的應(yīng)用程序以快捷圖標(biāo)的形式展示在桌面上，這樣用戶就可以使用這些應(yīng)用程序了，整個(gè)過程如下圖所示：MM-KlJtnBfirUrchH'ft*iMumm點(diǎn)擊查看大圖下面詳細(xì)分析每一個(gè)步驟。Step1.SystemServer.main

3、這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/SystemServer.java文件中，具體可以參考前面一篇文章Android應(yīng)用程序安裝過程源代碼分析的Step1。Step2.SystemServer.init1這個(gè)函數(shù)是一個(gè)JNI方法，實(shí)現(xiàn)在frameworks/base/services/jni/com_android_server_SystemServer.cpp文件中，具體可以參考前面一篇文章Android應(yīng)用程序安裝過程源代碼分析的Step2。Step3.libsystem_server.system_init函數(shù)s

4、ystem_init實(shí)現(xiàn)在libsystem_server庫(kù)中，源代碼位于frameworks/base/cmds/system_server/library/system_init.cpp文件中,具體可以參考前面一篇文章Android應(yīng)用程序安裝過程源代碼分析的Step3。Step4.AndroidRuntime.callStatic這個(gè)函數(shù)定義在frameworks/base/core/jni/AndroidRuntime.cpp文件中，具體可以參考前面一篇文章Android應(yīng)用程序安裝過程源代碼分析的Step4。Step5.SystemServer.init2這個(gè)函數(shù)定義在framewo

5、rks/base/services/java/com/android/server/SystemServer.java文件中，具體可以參考前面一篇文章Android應(yīng)用程序安裝過程源代碼分析的Step5。Step6.ServerThread.run這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/SystemServer.java文件中，具體可以參考前面一篇文章Android應(yīng)用程序安裝過程源代碼分析的Step6。Step7.ActivityManagerService.main這個(gè)函數(shù)定義在frameworks/base/serv

6、ices/java/com/android/server/am/ActivityManagerServcie.java文件中：viewplain1. publicfinalclassActivityManagerServiceextendsActivityManagerNative2. implementsWatchdog.Monitor,BatteryStatsImpl.BatteryCallback3. .4.5. publicstaticfinalContextmain(intfactoryTest)6. AThreadthr=newAThread。；7. thr.start();8.9

7、. synchronized(thr)10. while(thr.mService=null)11. try12. thr.wait。；13. catch(InterruptedExceptione)14. 15. 16. 17.19. mSelf=m;20. ActivityThreadat=ActivityThread.systemMain();21. mSystemThread=at;22. Contextcontext=at.getSystemContext();23. m.mContext=context;24. m.mFactoryTest=factoryTest;true);25

8、. m.mMainStack=newActivityStack(m,context,26.27. m.mBatteryStatsService.publish(context);28. m.mUsageStatsService.publish(context);29.30. synchronized(thr)31. thr.mReady=true;32. thr.notifyAll();33. 34.35. m.startRunning(null,null,null,null);36.37. returncontext;38. 39.40.41. 這個(gè)函數(shù)首先通過AThread線程對(duì)象來內(nèi)部創(chuàng)

9、建了一個(gè)ActivityManagerService實(shí)例，然后將這個(gè)實(shí)例保存其成員變量mService中，接著又把這個(gè)ActivityManagerService實(shí)例保存在ActivityManagerService類的靜態(tài)成員變量mSelf中，最后初始化其它成員變量，就結(jié)束了。Step8.PackageManagerService.main這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/PackageManagerService.java文件中，具體可以參考前面一篇文章Android應(yīng)用程序安裝過程源代碼分析的Step7。執(zhí)行完

10、這一步之后，系統(tǒng)中的應(yīng)用程序的所有信息都保存在PackageManagerService中了，后面Home應(yīng)用程序Launcher啟動(dòng)起來后，就會(huì)把PackageManagerService中的應(yīng)用程序信息取出來，然后以快捷圖標(biāo)的形式展示在桌面上，后面我們將會(huì)看到這個(gè)過程。Step9.ActivityManagerService.setSystemProcess這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/am/ActivityManagerServcie.java文件中：viewplain1. publicfinalclass

11、ActivityManagerServiceextendsActivityManagerNative2. implementsWatchdog.Monitor,BatteryStatsImpl.BatteryCallback3. .4.5. publicstaticvoidsetSystemProcess()6. try7.ActivityManagerServicem=mSelf;8.39.40.ServiceMan

12、ager.addService("activity",m);ServiceManager.addService("meminfo",newMemBinder(m);if(MONITOR_CPU_USAGE)ServiceManager.addService("cpuinfo",newCpuBinder(m);ServiceManager.addService("permission",newPermissionController(m);ApplicationInfoinfo=mSelf.mContext.getP

13、ackageManager().getApplicationInfo("android",STOCK_PM_FLAGS);mSystemThread.installSystemApplicationInfo(info);synchronized(mSelf)ProcessRecordapp=mSelf.newProcessRecordLocked(mSystemThread.getApplicationThread(),info,cessName);app.persistent=true;app.pid=MY_PID;app.maxAdj=SYSTEM_AD

14、J;mSelf.mProcessNames.put(cessName,.uid,app);synchronized(mSelf.mPidsSelfLocked)mSelf.mPidsSelfLocked.put(app.pid,app);mSelf.updateLruProcessLocked(app,true,true);catch(PackageManager.NameNotFoundExceptione)thrownewRuntimeException("Unabletofindandroidsystempackage",e);這個(gè)函數(shù)首

15、先是將這個(gè)ActivityManagerService實(shí)例添加到ServiceManager中去托管，這樣其它地方就可以通過ServiceManager.getService接口來訪問這個(gè)全局唯一的ActivityManagerService實(shí)例了，接著又通過調(diào)用mSystemThread.installSystemApplicationInfo函數(shù)來把應(yīng)用程序框架層下面的android包加載進(jìn)來，這里的mSystemThread是一個(gè)ActivityThread類型的實(shí)例變量，它是在上面的Step7中創(chuàng)建的，后面就是一些其它的初始化工作了。Step10.ActivityManagerServ

16、ice.systemReady這個(gè)函數(shù)是在上面的Step6中的ServerThread.run函數(shù)在將系統(tǒng)中的一系列服務(wù)都初始化完畢之后才調(diào)用的,它定義在frameworks/base/services/java/com/android/server/am/ActivityManagerServcie.java文件中：viewplain1.publicfinalclassActivityManagerServiceextendsActivityManagerNative..6.implementsWatchdog.Monitor

17、,BatteryStatsImpl.BatteryCallbackpublicvoidsystemReady(finalRunnablegoingCallback)synchronized(this)mMainStack.resumeTopActivityLocked(null);..6.17.18.這個(gè)函數(shù)的內(nèi)容比較多，這里省去無關(guān)的部分，主要關(guān)心啟動(dòng)Home應(yīng)用程序的邏輯，這里就是通過mMainStack.resumeTopActivityLocked函數(shù)來啟動(dòng)Home應(yīng)用程序的了，這里的mMainStack是一個(gè)Activ

18、ityStack類型的實(shí)例變量。Step11.ActivityStack.resumeTopActivityLocked這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/am/ActivityStack.java文件中:viewplain1.publicclassActivityStackfinalbooleanresumeTopActivityLocked(ActivityRecordprev)/Findthefirstactivitythatisnotfinishing.null);ActivityRecordnext=topR

19、unningActivityLocked(if(next=null)/Therearenomoreactivities!Let'sjuststartupthe/Launcher.if(mMainStack)returnmService.startHomeActivityLocked();22.這里調(diào)用函數(shù)topRunningActivityLocked返回的是當(dāng)前系統(tǒng)Activity堆棧最頂端的Activity,由于此時(shí)還沒有Activity被啟動(dòng)過，因此，返回值為null,即next變量的值為null,于是就調(diào)用mService.startHomeActivityLocked語(yǔ)句，這

20、里的mService就是前面在Step7中創(chuàng)建的ActivityManagerService實(shí)例了。Step12.ActivityManagerService.startHomeActivityLocked這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/am/ActivityManagerServcie.java文件中：viewplain1. publicfinalclassActivityManagerServiceextendsActivityManagerNative2. implementsWatchdog.Monitor

21、,BatteryStatsImpl.BatteryCallback3. .4.5. booleanstartHomeActivityLocked()6. .7.8. Intentintent=newIntent(9. mTopAction,10. mTopData!=null?Uri.parse(mTopData):null);11. intent.setComponent(mTopComponent);12. if(mFactoryTest!=SystemServer.FACTORY_TEST_LOW_LEVEL)13. intent.addCategory(Intent.CATEGORY_

22、HOME);14. 15. ActivityInfoaInfo=16. intent.resolveActivityInfo(mContext.getPackageManager(),17. STOCK_PM_FLAGS);18. if(aInfo!=null)19. intent.setComponent(newComponentName(20. aInfo.applicationInfo.packageName,aI);21. /Don'tdothisifthehomeappiscurrentlybeing22. /instrumented.23. ProcessR

23、ecordapp=getProcessRecordLocked(aIcessName,24. aInfo.applicationInfo.uid);25. if(app=null|app.instrumentationClass=null)26. intent.setFlags(intent.getFlags()|Intent.FLAG_ACTIVITY_NEW_TASK);27. mMainStack.startActivityLocked(null,intent,null,null,0,aInfo,28. null,null,0,0,0,false,false);29. 30

24、. 33. 34.35.36. 函數(shù)首先創(chuàng)建個(gè)CATEGORY_HOME類型的Intent,然后通過Intent.resolveActivityInfo函數(shù)向PackageManagerService查詢Category類型為HOME的Activity，這里我們假設(shè)只有系統(tǒng)自帶的Launcher應(yīng)用程序注冊(cè)了HOME類型的Activity(見packages/apps/Launcher2/AndroidManifest.xml文件)：viewplain1. <manifest2. xmlns:android="3. package="com.android.launc

25、her"4. android:sharedUserId="string/sharedUserId"5. >6.7. .8.9. application10. android:name="com.android.launcher2.LauncherApplication"11. android:process="。string/process"12. android:label="string/application_name"13. android:icon="drawable/ic_la

26、uncher_home">14.15. <activity16. android:name="com.android.launcher2.Launcher"17. android:launchMode="singleTask"18. android:clearTaskOnLaunch="true"19. android:stateNotNeeded="true"20. android:theme="style/Theme"21. android:screenOrientat

27、ion22. android:windowSoftInputMode23. <intent-filter>24. <actionandroid:name25. <categoryandroid:name26. <categoryandroid:name27. <categoryandroid:name28. </intent-filter>29. </activity>30.31. .32. </application>33. /manifest)="nosensor"="stateUnspe

28、cified|adjustPan">="ent.action.MAIN"/>="ent.category.HOME"/>="ent.category.DEFAULT"/>="ent.category.MONKEY"/>因此，這里就返回com.android.launcher2.Launcher這個(gè)Activity了。由于是第一次啟動(dòng)這個(gè)Activity,接下來調(diào)用函數(shù)getProcessR

29、ecordLocked返回來的ProcessRecord值為null,于是，就調(diào)用mMainStack.startActivityLocked函數(shù)啟動(dòng)com.android.launcher2.Launcher這個(gè)Activity了,這里的mMainStack是一個(gè)ActivityStack類型的成員變量。Step13.ActivityStack.startActivityLocked這個(gè)函數(shù)定義在frameworks/base/services/java/com/android/server/am/ActivityStack.java文件中,具體可以參考Android應(yīng)用程序啟動(dòng)過程源代碼分

30、析一文，這里就不詳述了，在我們這個(gè)場(chǎng)景中，調(diào)用這個(gè)函數(shù)的最后結(jié)果就是把com.android.launcher2.Launcher啟動(dòng)起來，接著調(diào)用它的onCreate函數(shù)。Step14.Launcher.onCreate這個(gè)函數(shù)定義在packages/apps/Launcher2/src/com/android/launcher2/Launcher.java文件中：viewplain1. publicfinalclassLauncherextendsActivity2. implementsView.OnClickListener,OnLongClickListener,LauncherMo

31、del.Callbacks,AllAppsView.Watcher3. .4.5. Override6. protectedvoidonCreate(BundlesavedInstanceState)7. .8.9. if(!mRestoring)10. mModel.startLoader(this,true);11. 12.13. .14. 15.16.17. 這里的mModel是一個(gè)LauncherModel類型的成員變量，這里通過調(diào)用它的startLoader成員函數(shù)來執(zhí)行加應(yīng)用程序的操作。Step15.LauncherModel.startLoader|這個(gè)函數(shù)定義在packages

32、/apps/Launcher2/src/com/android/launcher2/LauncherModel.java文件中：viewplain.publicclassLauncherModelextendsBroadcastReceiverpublicvoidstartLoader(Contextcontext,booleanisLaunching)7. synchronized(mLock)8. .9.10. /Don'tbothertostartthethreadifweknowit'snotgoingtodoanything11. if(mCallbac

33、ks!=null&&mCallbacks.get()!=null)12. /Ifthereisalreadyonerunning,tellittostop.13. LoaderTaskoldTask=mLoaderTask;14. if(oldTask!=null)15. if(oldTask.isLaunchingO)16. /don'tdowngradeisLaunchingifwe'realreadyrunning17. isLaunching=true;18. 19. oldTask.stopLocked();20. 21. mLoaderTask=ne

34、wLoaderTask(context,isLaunching);22. sWorker.post(mLoaderTask);23. 24. 25. 26.27.28. 這里不是直接加載應(yīng)用程序，而是把加載應(yīng)用程序的操作作為一個(gè)消息來處理。這里的sWorker是一個(gè)Handler,通過它的post方式把一個(gè)消息放在消息隊(duì)列中去，然后系統(tǒng)就會(huì)調(diào)用傳進(jìn)去的參數(shù)mLoaderTask的run函數(shù)來處理這個(gè)消息，這個(gè)mLoaderTask是LoaderTask類型的實(shí)例，于是，下面就會(huì)執(zhí)行LoaderTask類的run函數(shù)了。Step16.LoaderTask.run這個(gè)函數(shù)定義在packages/a

35、pps/Launcher2/src/com/android/launcher2/LauncherModel.java文件中：viewplain1. publicclassLauncherModelextendsBroadcastReceiver2. .3.4. privateclassLoaderTaskimplementsRunnable5. .6.7. publicvoidrun()8. .9.10. keep_running:12.13. /secondstep14. if(loadWorkspaceFirst)15. .16. loadAndBindAllApps();17. else

36、18. .19. 20.21. .22. 23.24. .25. 26.27. .28. 29. 3031. 這里調(diào)用loadAndBindAllApps成員函數(shù)來進(jìn)一步操作。Step17.LoaderTask.loadAndBindAllApps這個(gè)函數(shù)定義在packages/apps/Launcher2/src/com/android/launcher2/LauncherModel.java文件中：viewplain1. publicclassLauncherModelextendsBroadcastReceiver2. .3.4. privateclassLoaderTaskimplem

37、entsRunnable5. .6.7. privatevoidloadAndBindAllApps。8. .9.10. if(!mAllAppsLoaded)11. loadAllAppsByBatch();12. if(mStopped)13. return;14. 15. mAllAppsLoaded=true;16. else18.19. 20.21.22. .23. 24.25.26. 由于還沒有加載過應(yīng)用程序，這里的mAllAppsLoaded為false，于是就繼續(xù)調(diào)用loadAllAppsByBatch函數(shù)來進(jìn)一步操作了。Step18.LoaderTask.loadAllApp

38、sByBatch這個(gè)函數(shù)定義在packages/apps/Launcher2/src/com/android/launcher2/LauncherModel.java文件中：viewplain..4.25.26.publicclassLauncherModelextendsBroadcastReceiverprivateclassLoaderTaskimplementsRunnableprivatevoidloadAllAppsByBatch。finalIntentmainIn

39、tent=newIntent(Intent.ACTION_MAIN,null);mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);finalPackageManagerpackageManager=mContext.getPackageManager。；List<ResolveInfo>apps=null;intN=Integer.MAX_VALUE;intstartIndex;inti=0;intbatchSize=-1;while(i<N&&!mStopped)if(i=0)mAllAppsList.clea

40、r。；apps=packageManager.queryIntentActivities(mainIntent,0);0.71.N=apps.size();if(mBatchSize=0)batchSize=N;elsebatchSize=mBatchSize;Collections.sort(apps,newResolveInfo.Displ

41、ayNameComparator(packageManager);startIndex=i;for(intj=0;i<N&&j<batchSize;j+)/Thisbuildstheiconbitmaps.mAllAppsList.add(newApplicationInfo(apps.get(i),mIconCache);i+;finalbooleanfirst=i<=batchSize;finalCallbackscallbacks=tryGetCallbacks(oldCallbacks);finalArrayList<ApplicationInf

42、o>added=mAllAppsList.added;mAllAppsList.added=newArrayList<ApplicationInfo>();mHandler.post(newRunnable。publicvoidrun()finallongt=SystemClock.uptimeMillis();if(callbacks!=null)if(first)callbacks.bindAllApplications(added);elsecallbacks.bindAppsAdded(added);else);72.73. .74. )75.76. .77. )78

43、.79. .80. 81.82.83. 函數(shù)首先構(gòu)造一個(gè)CATEGORY_LAUNCHER類型的Intent:viewplain1. finalIntentmainIntent=newIntent(Intent.ACTION_MAIN,null);2. mainIntent.addCategory(Intent.CATEGORY_LAUNCHER);接著從mContext變量中獲得PackageManagerService的接口：viewplain1. finalPackageManagerpackageManager=mContext.getPackageManager。；下一步就是通過這個(gè)

44、PackageManagerService.queryIntentActivities接口來取回所有Action類型為Intent.ACTION_MAIN,并且Category類型為Intent.CATEGORY_LAUNCHER的Activity了。我們先進(jìn)入到PackageManagerService.queryIntentActivities函數(shù)中看看是如何獲得這些Activity的,然后再回到這個(gè)函數(shù)中來看其余操作。Step19.PackageManagerService.queryIntentActivities這個(gè)函數(shù)定義在frameworks/base/services/java

45、/com/android/server/PackageManagerService.java文件中：viewplain2. classPackageManagerServiceextendsIPackageManager.Stub3. .4.5. publicList<ResolveInfo>queryIntentActivities(Intentintent,6. StringresolvedType,intflags)7. .8.9. synchronized(mPackages)10. StringpkgName=intent.getPackage。；11. if(pkgNa

46、me=null)12. return(List<ResolveInfo>)mActivities.queryIntent(intent,12.resolvedType,flags);13. 14.15. .16. 17.18. .19. 20.21.22. 回憶前面一篇文章Android應(yīng)用程序安裝過程源代碼分析，系統(tǒng)在前面的Step8中啟動(dòng)PackageManagerService時(shí)，會(huì)把系統(tǒng)中的應(yīng)用程序都解析一遍，然后把解析得到的Activity都保存在mActivities變量中，這里通過這個(gè)mActivities變量的queryIntent函數(shù)返回符合條件intent的Ac

47、tivity,這里要返回的便是Action類型為Intent.ACTION_MAIN,并且Category類型為Intent.CATEGORY_LAUNCHER的Activity了。回到Step18中的LoaderTask.loadAllAppsByBatch函數(shù)中，從queryIntentActivities函數(shù)調(diào)用處返回所要求的Activity后，便調(diào)用函數(shù)tryGetCallbacks(oldCallbacks)得到一個(gè)返CallBack接口，這個(gè)接口是由Launcher類實(shí)現(xiàn)的，接著調(diào)用這個(gè)接口的.bindAllApplications函數(shù)來進(jìn)一步操作。注意，這里又是通過消息來處理加載

48、應(yīng)用程序的操作的。Step20.Launcher.bindAllApplications這個(gè)函數(shù)定義在packages/apps/Launcher2/src/com/android/launcher2/Launcher.java文件中：viewplain1. publicfinalclassLauncherextendsActivity2. implementsView.OnClickListener,OnLongClickListener,LauncherModel.Callbacks,AllAppsView.Watcher3. .4.5. privateAllAppsViewmAllApp

49、sGrid;6.7. .8.9. publicvoidbindAllApplications(ArrayList<ApplicationInfo>apps)10. mAllAppsGrid.setApps(apps);11. 12.13.14. 這里的mAllAppsGrid是一個(gè)AllAppsView類型的變量，它的實(shí)際類型一般就是AllApps2D了Step21.AllApps2D.setApps文件中:這個(gè)函數(shù)定義在packages/apps/Launcher2/src/com/android/launcher2/AllApps2D.javaviewplain1. publi

50、cclassAllApps2D2. extendsRelativeLayout3. implementsAllAppsView,4. AdapterView.OnItemClickListener,5. AdapterView.OnItemLongClickListener,6. View.OnKeyListener,7. DragSource8.9. .10.11. publicvoidsetApps(ArrayList<ApplicationInfo>list)12. mAllAppsList.clear。；13. addApps(list);14. 15.16. public

51、voidaddApps(ArrayList<ApplicationInfo>list)17. finalintN=list.size。；18.19. for(inti=0;i<N;i+)20. finalApplicationInfoitem=list.get(i);21. intindex=Collections.binarySearch(mAllAppsList,item,22. LauncherModel.APP_NAME_COMPARATOR);23. if(index<0)24. index=-(index+1);25. 26. mAllAppsList.add(index,item);27. 28. mAppsAdapter.notifyDataSetChanged();29. 30.31.32. 函數(shù)setApps首先清空mAllAppsList列表，然后調(diào)用addApps函數(shù)來為上一步