Android源码分析(十四)PackageManagerService服务分析
一. PackageManagerService启动过程分析
PackageManagerService(PMS)主要是管理应用的安装,卸载,更新,解析以及权限。如果想了解SystemService启动过程请看这篇文章:Android 源码分析(六) SystemServer 进程
如果想了解AMS服务分析请看这篇文章:Android源码分析(十三)ActivityManagerService服务分析
同AMS一样,PMS也是由SystemServer启动的.
public final class SystemServer { private PackageManagerService mPackageManagerService; private PackageManager mPackageManager; ... // Start the package manager. //启动PMS服务 if (!mRuntimeRestart) { MetricsLogger.histogram(null, "boot_package_manager_init_start", (int) SystemClock.elapsedRealtime()); } traceBeginAndSlog("StartPackageManagerService"); mPackageManagerService = PackageManagerService.main(mSystemContext, installer, mFactoryTestMode != FactoryTest.FACTORY_TEST_OFF, mOnlyCore); mFirstBoot = mPackageManagerService.isFirstBoot(); mPackageManager = mSystemContext.getPackageManager(); traceEnd(); if (!mRuntimeRestart && !isFirstBootOrUpgrade()) { MetricsLogger.histogram(null, "boot_package_manager_init_ready", (int) SystemClock.elapsedRealtime()); } ... }
//PackageManagerService 初始化工作 public class PackageManagerService extends IPackageManager.Stub implements PackageSender { public static PackageManagerService main(Context context, Installer installer, boolean factoryTest, boolean onlyCore) { // Self-check for initial settings. PackageManagerServiceCompilerMapping.checkProperties(); //构造一个PackageManagerService PackageManagerService m = new PackageManagerService(context, installer, factoryTest, onlyCore); m.enableSystemUserPackages(); //添加到ServiceManager ServiceManager.addService("package", m); return m; } public PackageManagerService(Context context, Installer installer, boolean factoryTest, boolean onlyCore) { //installer apk的安装和卸载最终都是调用installd来实现的。 mInstaller = installer; mPackageDexOptimizer = new PackageDexOptimizer(installer, mInstallLock, context, "*dexopt*"); mDexManager = new DexManager(this, mPackageDexOptimizer, installer, mInstallLock); mMoveCallbacks = new MoveCallbacks(FgThread.get().getLooper()); synchronized (mInstallLock) { // writer //环境变量初始化 synchronized (mPackages) { File dataDir = Environment.getDataDirectory(); mAppInstallDir = new File(dataDir, "app"); mAppLib32InstallDir = new File(dataDir, "app-lib"); mAsecInternalPath = new File(dataDir, "app-asec").getPath(); mDrmAppPrivateInstallDir = new File(dataDir, "app-private"); sUserManager = new UserManagerService(context, this, new UserDataPreparer(mInstaller, mInstallLock, mContext, mOnlyCore), mPackages); //权限注册到 package manager,一个权限与几个组ID对应,当一个APK授予这个权限时,它同属于这几个组。 //权限是一个复杂的过程 // Propagate permission configuration in to package manager. ArrayMap<String, SystemConfig.PermissionEntry> permConfig = systemConfig.getPermissions(); //遍历权限配置文件 for (int i=0; i<permConfig.size(); i++) { SystemConfig.PermissionEntry perm = permConfig.valueAt(i); //拿到权限 BasePermission bp = mSettings.mPermissions.get(perm.name); if (bp == null) { bp = new BasePermission(perm.name, "android", BasePermission.TYPE_BUILTIN); //写入权限 mSettings.mPermissions.put(perm.name, bp); } if (perm.gids != null) { bp.setGids(perm.gids, perm.perUser); } } } final PackageHandler mHandler; class PackageHandler extends Handler { void doHandleMessage(Message msg) { switch (msg.what) { } } private void scanDirLI(File dir, int parseFlags, int scanFlags, long currentTime) { final File[] files = dir.listFiles(); if (ArrayUtils.isEmpty(files)) { Log.d(TAG, "No files in app dir " + dir); return; } ParallelPackageParser parallelPackageParser = new ParallelPackageParser( mSeparateProcesses, mOnlyCore, mMetrics, mCacheDir, mParallelPackageParserCallback); parallelPackageParser.close(); } File frameworkDir = new File(Environment.getRootDirectory(), "framework"); // Find base frameworks (resource packages without code). scanDirTracedLI(frameworkDir, mDefParseFlags | PackageParser.PARSE_IS_SYSTEM | PackageParser.PARSE_IS_SYSTEM_DIR | PackageParser.PARSE_IS_PRIVILEGED, scanFlags | SCAN_NO_DEX, 0); // Collected privileged system packages. 系统安装包 final File privilegedAppDir = new File(Environment.getRootDirectory(), "priv-app"); scanDirTracedLI(privilegedAppDir, mDefParseFlags | PackageParser.PARSE_IS_SYSTEM | PackageParser.PARSE_IS_SYSTEM_DIR | PackageParser.PARSE_IS_PRIVILEGED, scanFlags, 0); // Collect ordinary system packages. 系统app安装包 final File systemAppDir = new File(Environment.getRootDirectory(), "app"); scanDirTracedLI(systemAppDir, mDefParseFlags | PackageParser.PARSE_IS_SYSTEM | PackageParser.PARSE_IS_SYSTEM_DIR, scanFlags, 0); }
PMS里面主要完成以下几件事。
1、通过installer与installd进行连接,进行安装卸载应用操作
2、创建PacakageHandler线程,处理外部应用的安装卸载请求
3、处理系统权限相关配置
4、扫描安装应用,并解析APK安装包信息
二.总结
一张图总结下PMS主要完成的工作,以及对上与PackageManager交互,向下与Installd的控制。如果想了解桌面Launcher应用启动app过程,请看这篇文章。Android 源码分析(八) Launcher 桌面启动App过程
最后补充一点,如果想要了解APK的编译过程,可以进一步去了解Android4.4之后使用的ART,可以与Dalivk对比了解。
给个Dalivk的启动过程介绍的文章:Android 源码分析(十) Dalvik 虚拟机创建过程
给个Dalivk的启动过程介绍的文章:Android 源码分析(十) Dalvik 虚拟机创建过程