Android应用程序安装过程源代码分析（3）
Step 7.PackageManagerService.main 这个函数定义在frameworks/base/services/java/com/android/server/PackageManagerService.java文件中： [cpp] view plain copy classPackageManagerServiceextendsIPackageManager.Stub{ ...... publicstaticfinalIPackageManagermain(Contextcontext,booleanfactoryTest){ PackageManagerServicem=newPackageManagerService(context,factoryTest); ServiceManager.addService("package",m); returnm; } ...... } 这个函数创建了一个PackageManagerService服务实例，然后把这个服务添加到ServiceManager中去，ServiceManager是Android系统Binder进程间通信机制的守护进程，负责管理系统中的Binder对象，具体可以参考 浅谈Service Manager成为Android进程间通信（IPC）机制Binder守护进程之路 一文。 在创建这个PackageManagerService服务实例时，会在PackageManagerService类的构造函数中开始执行安装应用程序的过程： [java] view plain copy classPackageManagerServiceextendsIPackageManager.Stub{ ...... publicPackageManagerService(Contextcontext,booleanfactoryTest){ ...... synchronized(mInstallLock){ synchronized(mPackages){ ...... FiledataDir=Environment.getDataDirectory(); mAppDataDir=newFile(dataDir,"data"); mSecureAppDataDir=newFile(dataDir,"secure/data"); mDrmAppPrivateInstallDir=newFile(dataDir,"app-private"); ...... mFrameworkDir=newFile(Environment.getRootDirectory(),"framework"); mDalvikCacheDir=newFile(dataDir,"dalvik-cache"); ...... //Findbaseframeworks(resourcepackageswithoutcode). mFrameworkInstallObserver=newAppDirObserver( mFrameworkDir.getPath(),OBSERVER_EVENTS,true); mFrameworkInstallObserver.startWatching(); scanDirLI(mFrameworkDir,PackageParser.PARSE_IS_SYSTEM |PackageParser.PARSE_IS_SYSTEM_DIR, scanMode|SCAN_NO_DEX,0); //Collectallsystempackages. mSystemAppDir=newFile(Environment.getRootDirectory(),"app"); mSystemInstallObserver=newAppDirObserver( mSystemAppDir.getPath(),OBSERVER_EVENTS,true); mSystemInstallObserver.startWatching(); scanDirLI(mSystemAppDir,PackageParser.PARSE_IS_SYSTEM |PackageParser.PARSE_IS_SYSTEM_DIR,scanMode,0); //Collectallvendorpackages. mVendorAppDir=newFile("/vendor/app"); mVendorInstallObserver=newAppDirObserver( mVendorAppDir.getPath(),OBSERVER_EVENTS,true); mVendorInstallObserver.startWatching(); scanDirLI(mVendorAppDir,PackageParser.PARSE_IS_SYSTEM |PackageParser.PARSE_IS_SYSTEM_DIR,scanMode,0); mAppInstallObserver=newAppDirObserver( mAppInstallDir.getPath(),OBSERVER_EVENTS,false); mAppInstallObserver.startWatching(); scanDirLI(mAppInstallDir,0,scanMode,0); mDrmAppInstallObserver=newAppDirObserver( mDrmAppPrivateInstallDir.getPath(),OBSERVER_EVENTS,false); mDrmAppInstallObserver.startWatching(); scanDirLI(mDrmAppPrivateInstallDir,PackageParser.PARSE_FORWARD_LOCK, scanMode,0); ...... } } } ...... } 这里会调用scanDirLI函数来扫描移动设备上的下面这五个目录中的Apk文件 /system/framework /system/app /vendor/app /data/app /data/app-private Step 8.PackageManagerService.scanDirLI 这个函数定义在frameworks/base/services/java/com/android/server/PackageManagerService.java文件中： [java] view plain copy classPackageManagerServiceextendsIPackageManager.Stub{ ...... privatevoidscanDirLI(Filedir,intflags,intscanMode,longcurrentTime){ String[]files=dir.list(); ...... inti; for(i=0;i<files.length;i++){ Filefile=newFile(dir,files[i]); if(!isPackageFilename(files[i])){ //Ignoreentrieswhicharenotapk's continue; } PackageParser.Packagepkg=scanPackageLI(file, flags|PackageParser.PARSE_MUST_BE_APK,scanMode,currentTime); //Don'tmessaroundwithappsinsystempartition. if(pkg==null&&(flags&PackageParser.PARSE_IS_SYSTEM)==0&& mLastScanError==PackageManager.INSTALL_FAILED_INVALID_APK){ //Deletetheapk Slog.w(TAG,"Cleaningupfailedinstallof"+file); file.delete(); } } } ...... } 对于目录中的每一个文件，如果是以后Apk作为后缀名，那么就调用scanPackageLI函数来对它进行解析和安装。 Step 9.PackageManagerService.scanPackageLI 这个函数定义在frameworks/base/services/java/com/android/server/PackageManagerService.java文件中： [java] view plain copy classPackageManagerServiceextendsIPackageManager.Stub{ ...... privatePackageParser.PackagescanPackageLI(FilescanFile, intparseFlags,intscanMode,longcurrentTime){ ...... StringscanPath=scanFile.getPath(); parseFlags|=mDefParseFlags; PackageParserpp=newPackageParser(scanPath); ...... finalPackageParser.Packagepkg=pp.parsePackage(scanFile, scanPath,mMetrics,parseFlags); ...... returnscanPackageLI(pkg,parseFlags,scanMode|SCAN_UPDATE_SIGNATURE,currentTime); } ...... } 这个函数首先会为这个Apk文件创建一个PackageParser实例，接着调用这个实例的parsePackage函数来对这个Apk文件进行解析。这个函数最后还会调用另外一个版本的scanPackageLI函数把来解析后得到的应用程序信息保存在PackageManagerService中。 本文转自 Luoshengyang 51CTO博客，原文链接：http://blog.51cto.com/shyluo/966522，如需转载请自行联系原作者
