2016六月 21

原

Android系統啟動流程分析之安裝應用

分類：Android系統源碼研究

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跟隨上一篇博客Android系統的啟動流程簡要分析繼續分析android系統的啟動.上一篇文章里講了,SystemServer在main方法里創建了一個線程ServerThread,并調用 initAndLoop方法. [java]?view plain?copy

ServerThread?thr?=?new?ServerThread();??

thr.initAndLoop();??

在initAndLoop方法里加載各種服務,比如WindowManagerService（Wms）、ActivityManagerService（Ams）、PackageManagerService（Pms）等. 看下啟動PackageManagerServer的代碼 [java]?view plain?copy

pm?=?PackageManagerService.main(context,?installer,?factoryTest?!=?SystemServer.FACTORY_TEST_OFF,?onlyCore);??

這個pm是IPackageManager的實例,IPackageManager是由IPackageManager.aidl文件編譯生成的. PackageManagerService繼承自IPackageManager.Stub [java]?view plain?copy

public?class?PackageManagerService?extends?IPackageManager.Stub?{??

PackageManagerService調用main方法,傳入四個參數 context 上下文 installer 安裝器 factoryTest != SystemServer.FACTORY_TEST_OFF 是否為正常的工廠模式 onlyCore 為true表示在加密的設備只啟動核心的程序
那么查看PackageManagerService的main方法.
PackageManagerService定義在frameworks/base/services/java/com/android/server/PackageManagerService.java文件中.

main方法是這樣的
[java]?view plain?copy

public?static?final?IPackageManager?main(Context?context,?Installer?installer,?boolean?factoryTest,?boolean?onlyCore)?{??

????????PackageManagerService?m?=?new?PackageManagerService(context,?installer,?factoryTest,?onlyCore);??

????????ServiceManager.addService("package",?m);??

????????return?m;??

????}??

根據傳入的四個參數創建PackageManagerService的實例,
然后通過ServiceManager添加這個PackageManagerService實例. 既然創建了這個實例,那么就調用了它的有參構造函數 1.在構造函數里會掃描制定目錄的apk文件 [java]?view plain?copy

//?掃描基礎框架(沒有代碼的資源包)。??????????????????

????????????????mFrameworkInstallObserver?=?new?AppDirObserver(frameworkDir.getPath(),?OBSERVER_EVENTS,?true,?false,?false);??

????????????????mFrameworkInstallObserver.startWatching();??

????????????????scanDirLI(frameworkDir,?PackageParser.PARSE_IS_SYSTEM?|?PackageParser.PARSE_IS_SYSTEM_DIR?|?PackageParser.PARSE_IS_PRIVILEGED,?scanMode?|?SCAN_NO_DEX,?0);??

??????????????????

????????????????//?掃描system/priv-app目錄?????????????

????????????????File?privilegedAppDir?=?new?File(Environment.getRootDirectory(),?"priv-app");??

????????????????mPrivilegedInstallObserver?=?new?AppDirObserver(privilegedAppDir.getPath(),?OBSERVER_EVENTS,?true,?true,?false);??

????????????????mPrivilegedInstallObserver.startWatching();??

????????????????scanDirLI(privilegedAppDir,?PackageParser.PARSE_IS_SYSTEM?|?PackageParser.PARSE_IS_SYSTEM_DIR?|?PackageParser.PARSE_IS_PRIVILEGED,?scanMode,?0);??

??

????????????????//?掃描system/app目錄??????????????????

????????????????File?systemAppDir?=?new?File(Environment.getRootDirectory(),?"app");??

????????????????mSystemInstallObserver?=?new?AppDirObserver(systemAppDir.getPath(),?OBSERVER_EVENTS,?true,?false,?false);??

????????????????mSystemInstallObserver.startWatching();??

????????????????scanDirLI(systemAppDir,?PackageParser.PARSE_IS_SYSTEM?|?PackageParser.PARSE_IS_SYSTEM_DIR,?scanMode,?0);??

??

????????????????//?掃描映射目錄??

????????????????File?vendorAppDir?=?new?File("/vendor/app");??

????????????????mVendorInstallObserver?=?new?AppDirObserver(vendorAppDir.getPath(),?OBSERVER_EVENTS,?true,?false,?false);??

????????????????mVendorInstallObserver.startWatching();??

????????????????scanDirLI(vendorAppDir,?PackageParser.PARSE_IS_SYSTEM?|?PackageParser.PARSE_IS_SYSTEM_DIR,?scanMode,?0);??

掃描調用的方法是scanDirLI,傳入四個參數,context(上下文),flag(標志),scanMode(掃描模式),currentTime(當前時間). 2.在scanDirLI方法內部會調用 [java]?view plain?copy

PackageParser.Package?pkg?=?scanPackageLI(file,?flags?|?PackageParser.PARSE_MUST_BE_APK,?scanMode,?currentTime,?null);??

3.scanPackageLI通過解析安裝包parsePackage獲取到安裝包的信息結構 [java]?view plain?copy

PackageParser?pp?=?new?PackageParser(scanPath)??

????????pp.setSeparateProcesses(mSeparateProcesses);??

????????pp.setOnlyCoreApps(mOnlyCore);??

????????final?PackageParser.Package?pkg?=?pp.parsePackage(scanFile,?scanPath,?mMetrics,?parseFlags);??

4.之后調用parsePackage的重載方法解析,將應用信息保存在PackageManagerService,比如VersionCode、VersionName等 [java]?view plain?copy

try?{??

???????????//?XXXX?todo:?need?to?figure?out?correct?configuration.??

???????????pkg?=?parsePackage(res,?parser,?flags,?errorText);??

???????}?catch?(Exception?e)?{??

???????????errorException?=?e;??

???????????mParseError?=?PackageManager.INSTALL_PARSE_FAILED_UNEXPECTED_EXCEPTION;??

???????}??

5.回到第3步,調用scanPackageLI的重載方法 [java]?view plain?copy

PackageParser.Package?scannedPkg?=?scanPackageLI(pkg,?parseFlags,?scanMode?|?SCAN_UPDATE_SIGNATURE,?currentTime,?user);6.??

6.然后調用createDataDirsLI方法 [java]?view plain?copy

//?And?now?re-install?the?app.??

ret?=?createDataDirsLI(pkgName,?pkg.applicationInfo.uid,?pkg.applicationInfo.seinfo);??

7.在createDataDirsLI方法里調用mInstaller的install方法進行安裝. [java]?view plain?copy

int?res?=?mInstaller.install(packageName,?uid,?uid,?seinfo);??

版權聲明：本文為博主原創文章，轉載請注明出處：鄧志勇博客 http://blog.csdn.net/qq_31530015/

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