Step1、
这个函数定义在frameworks/base/services/java/com/android/server/SystemServer.java文件中:
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- public class SystemServer
- {
- ……
- public static final void init2() {
- Slog.i(TAG, “Entered the Android system server!”);
- Thread thr = new ServerThread();
- thr.setName(“android.server.ServerThread”);
- thr.start();
- }
- }
这个函数创建了一个ServerThread线程,PackageManagerService服务就是这个线程中启动的了。这里调用了ServerThread实例thr的start函数之后,下面就会执行这个实例的run函数了。
这个函数定义在frameworks/base/services/java/com/android/server/SystemServer.java文件中:
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- class ServerThread extends Thread {
- ……
- @Override
- public void run() {
- ……
- IPackageManager pm = null;
- ……
- // Critical services…
- try {
- ……
- Slog.i(TAG, “Package Manager”);
- pm = PackageManagerService.main(context,
- factoryTest != SystemServer.FACTORY_TEST_OFF);
- ……
- } catch (RuntimeException e) {
- Slog.e(“System”, “Failure starting core service”, e);
- }
- ……
- }
- ……
- }
这个函数除了启动PackageManagerService服务之外,还启动了其它很多的服务,例如在前面学习Activity和Service的几篇文章中经常看到的ActivityManagerService服务,有兴趣的读者可以自己研究一下。
这个函数定义在frameworks/base/services/java/com/android/server/PackageManagerService.java文件中:
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- class PackageManagerService extends IPackageManager.Stub {
- ……
- public static final IPackageManager main(Context context, boolean factoryTest) {
- PackageManagerService m = new PackageManagerService(context, factoryTest);
- ServiceManager.addService(“package”, m);
- return m;
- }
- ……
- }
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。
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:
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- class PackageManagerService extends IPackageManager.Stub {
- ……
- public PackageManagerService(Context context, boolean factoryTest) {
- ……
- synchronized (mInstallLock) {
- synchronized (mPackages) {
- ……
- File dataDir = Environment.getDataDirectory();
- mAppDataDir = new File(dataDir, “data”);
- mSecureAppDataDir = new File(dataDir, “secure/data”);
- mDrmAppPrivateInstallDir = new File(dataDir, “app-private”);
- ……
- mFrameworkDir = new File(Environment.getRootDirectory(), “framework”);
- mDalvikCacheDir = new File(dataDir, “dalvik-cache”);
- ……
- // Find base frameworks (resource packages without code).
- mFrameworkInstallObserver = new AppDirObserver(
- mFrameworkDir.getPath(), OBSERVER_EVENTS, true);
- mFrameworkInstallObserver.startWatching();
- scanDirLI(mFrameworkDir, PackageParser.PARSE_IS_SYSTEM
- | PackageParser.PARSE_IS_SYSTEM_DIR,
- scanMode | SCAN_NO_DEX, 0);
- // Collect all system packages.
- mSystemAppDir = new File(Environment.getRootDirectory(), “app”);
- mSystemInstallObserver = new AppDirObserver(
- mSystemAppDir.getPath(), OBSERVER_EVENTS, true);
- mSystemInstallObserver.startWatching();
- scanDirLI(mSystemAppDir, PackageParser.PARSE_IS_SYSTEM
- | PackageParser.PARSE_IS_SYSTEM_DIR, scanMode, 0);
- // Collect all vendor packages.
- mVendorAppDir = new File(“/vendor/app”);
- mVendorInstallObserver = new AppDirObserver(
- mVendorAppDir.getPath(), OBSERVER_EVENTS, true);
- mVendorInstallObserver.startWatching();
- scanDirLI(mVendorAppDir, PackageParser.PARSE_IS_SYSTEM
- | PackageParser.PARSE_IS_SYSTEM_DIR, scanMode, 0);
- mAppInstallObserver = new AppDirObserver(
- mAppInstallDir.getPath(), OBSERVER_EVENTS, false);
- mAppInstallObserver.startWatching();
- scanDirLI(mAppInstallDir, 0, scanMode, 0);
- mDrmAppInstallObserver = new AppDirObserver(
- 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
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- class PackageManagerService extends IPackageManager.Stub {
- ……
- private void scanDirLI(File dir, int flags, int scanMode, long currentTime) {
- String[] files = dir.list();
- ……
- int i;
- for (i=0; i<files.length; i++) {
- File file = new File(dir, files[i]);
- if (!isPackageFilename(files[i])) {
- // Ignore entries which are not apk’s
- continue;
- }
- PackageParser.Package pkg = scanPackageLI(file,
- flags|PackageParser.PARSE_MUST_BE_APK, scanMode, currentTime);
- // Don’t mess around with apps in system partition.
- if (pkg == null && (flags & PackageParser.PARSE_IS_SYSTEM) == 0 &&
- mLastScanError == PackageManager.INSTALL_FAILED_INVALID_APK) {
- // Delete the apk
- Slog.w(TAG, “Cleaning up failed install of “ + 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。
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- class PackageManagerService extends IPackageManager.Stub {
- ……
- private PackageParser.Package scanPackageLI(File scanFile,
- int parseFlags, int scanMode, long currentTime) {
- ……
- String scanPath = scanFile.getPath();
- parseFlags |= mDefParseFlags;
- PackageParser pp = new PackageParser(scanPath);
- ……
- final PackageParser.Package pkg = pp.parsePackage(scanFile,
- scanPath, mMetrics, parseFlags);
- ……
- return scanPackageLI(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。
这个函数定义在frameworks/base/core/java/android/content/pm/PackageParser.java文件中:
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- public class PackageParser {
- ……
- public Package parsePackage(File sourceFile, String destCodePath,
- DisplayMetrics metrics, int flags) {
- ……
- mArchiveSourcePath = sourceFile.getPath();
- ……
- XmlResourceParser parser = null;
- AssetManager assmgr = null;
- boolean assetError = true;
- try {
- assmgr = new AssetManager();
- int cookie = assmgr.addAssetPath(mArchiveSourcePath);
- if(cookie != 0) {
- parser = assmgr.openXmlResourceParser(cookie, “AndroidManifest.xml”);
- assetError = false;
- } else {
- ……
- }
- } catch (Exception e) {
- ……
- }
- ……
- String[] errorText = new String[1];
- Package pkg = null;
- Exception errorException = null;
- try {
- // XXXX todo: need to figure out correct configuration.
- Resources res = new Resources(assmgr, metrics, null);
- pkg = parsePackage(res, parser, flags, errorText);
- } catch (Exception e) {
- ……
- }
- ……
- parser.close();
- assmgr.close();
- // Set code and resource paths
- pkg.mPath = destCodePath;
- pkg.mScanPath = mArchiveSourcePath;
- //pkg.applicationInfo.sourceDir = destCodePath;
- //pkg.applicationInfo.publicSourceDir = destRes;
- pkg.mSignatures = null;
- return pkg;
- }
- ……
- }
每一个Apk文件都是一个归档文件,它里面包含了Android应用程序的配置文件AndroidManifest.xml,这里主要就是要对这个配置文件就行解析了,从Apk归档文件中得到这个配置文件后,就调用另一外版本的parsePackage函数对这个应用程序进行解析了:
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- public class PackageParser {
- ……
- private Package parsePackage(
- Resources res, XmlResourceParser parser, int flags, String[] outError)
- throws XmlPullParserException, IOException {
- ……
- String pkgName = parsePackageName(parser, attrs, flags, outError);
- ……
- final Package pkg = new Package(pkgName);
- ……
- int type;
- ……
- TypedArray sa = res.obtainAttributes(attrs,
- com.android.internal.R.styleable.AndroidManifest);
- ……
- while ((type=parser.next()) != parser.END_DOCUMENT
- && (type != parser.END_TAG || parser.getDepth() > outerDepth)) {
- if (type == parser.END_TAG || type == parser.TEXT) {
- continue;
- }
- String tagName = parser.getName();
- if (tagName.equals(“application”)) {
- ……
- if (!parseApplication(pkg, res, parser, attrs, flags, outError)) {
- return null;
- }
- } else if (tagName.equals(“permission-group”)) {
- ……
- } else if (tagName.equals(“permission”)) {
- ……
- } else if (tagName.equals(“permission-tree”)) {
- ……
- } else if (tagName.equals(“uses-permission”)) {
- ……
- } else if (tagName.equals(“uses-configuration”)) {
- ……
- } else if (tagName.equals(“uses-feature”)) {
- ……
- } else if (tagName.equals(“uses-sdk”)) {
- ……
- } else if (tagName.equals(“supports-screens”)) {
- ……
- } else if (tagName.equals(“protected-broadcast”)) {
- ……
- } else if (tagName.equals(“instrumentation”)) {
- ……
- } else if (tagName.equals(“original-package”)) {
- ……
- } else if (tagName.equals(“adopt-permissions”)) {
- ……
- } else if (tagName.equals(“uses-gl-texture”)) {
- ……
- } else if (tagName.equals(“compatible-screens”)) {
- ……
- } else if (tagName.equals(“eat-comment”)) {
- ……
- } else if (RIGID_PARSER) {
- ……
- } else {
- ……
- }
- }
- ……
- return pkg;
- }
- ……
- }
这里就是对AndroidManifest.xml文件中的各个标签进行解析了,各个标签的含义可以参考官方文档
http://developer.android.com/guide/topics/manifest/manifest-intro.html
,这里我们只简单看一下application标签的解析,这是通过调用parseApplication函数来进行的。
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- public class PackageParser {
- ……
- private boolean parseApplication(Package owner, Resources res,
- XmlPullParser parser, AttributeSet attrs, int flags, String[] outError)
- throws XmlPullParserException, IOException {
- final ApplicationInfo ai = owner.applicationInfo;
- final String pkgName = owner.applicationInfo.packageName;
- TypedArray sa = res.obtainAttributes(attrs,
- com.android.internal.R.styleable.AndroidManifestApplication);
- ……
- int type;
- while ((type=parser.next()) != parser.END_DOCUMENT
- && (type != parser.END_TAG || parser.getDepth() > innerDepth)) {
- if (type == parser.END_TAG || type == parser.TEXT) {
- continue;
- }
- String tagName = parser.getName();
- if (tagName.equals(“activity”)) {
- Activity a = parseActivity(owner, res, parser, attrs, flags, outError, false);
- ……
- owner.activities.add(a);
- } else if (tagName.equals(“receiver”)) {
- Activity a = parseActivity(owner, res, parser, attrs, flags, outError, true);
- ……
- owner.receivers.add(a);
- } else if (tagName.equals(“service”)) {
- Service s = parseService(owner, res, parser, attrs, flags, outError);
- ……
- owner.services.add(s);
- } else if (tagName.equals(“provider”)) {
- Provider p = parseProvider(owner, res, parser, attrs, flags, outError);
- ……
- owner.providers.add(p);
- } else if (tagName.equals(“activity-alias”)) {
- Activity a = parseActivityAlias(owner, res, parser, attrs, flags, outError);
- ……
- owner.activities.add(a);
- } else if (parser.getName().equals(“meta-data”)) {
- ……
- } else if (tagName.equals(“uses-library”)) {
- ……
- } else if (tagName.equals(“uses-package”)) {
- ……
- } else {
- ……
- }
- }
- return true;
- }
- ……
- }
这里就是对AndroidManifest.xml文件中的application标签进行解析了,我们常用到的标签就有activity、service、receiver和provider,各个标签的含义可以参考官方文档
http://developer.android.com/guide/topics/manifest/manifest-intro.html
。
这里解析完成后,一层层返回到Step 9中,调用另一个版本的scanPackageLI函数把来解析后得到的应用程序信息保存下来。
这个函数定义在frameworks/base/services/java/com/android/server/PackageManagerService.java文件中:
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- class PackageManagerService extends IPackageManager.Stub {
- ……
- // Keys are String (package name), values are Package. This also serves
- // as the lock for the global state. Methods that must be called with
- // this lock held have the prefix “LP”.
- final HashMap<String, PackageParser.Package> mPackages =
- new HashMap<String, PackageParser.Package>();
- ……
- // All available activities, for your resolving pleasure.
- final ActivityIntentResolver mActivities =
- new ActivityIntentResolver();
- // All available receivers, for your resolving pleasure.
- final ActivityIntentResolver mReceivers =
- new ActivityIntentResolver();
- // All available services, for your resolving pleasure.
- final ServiceIntentResolver mServices = new ServiceIntentResolver();
- // Keys are String (provider class name), values are Provider.
- final HashMap<ComponentName, PackageParser.Provider> mProvidersByComponent =
- new HashMap<ComponentName, PackageParser.Provider>();
- ……
- private PackageParser.Package scanPackageLI(PackageParser.Package pkg,
- int parseFlags, int scanMode, long currentTime) {
- ……
- synchronized (mPackages) {
- ……
- // Add the new setting to mPackages
- mPackages.put(pkg.applicationInfo.packageName, pkg);
- ……
- int N = pkg.providers.size();
- int i;
- for (i=0; i<N; i++) {
- PackageParser.Provider p = pkg.providers.get(i);
- p.info.processName = fixProcessName(pkg.applicationInfo.processName,
- p.info.processName, pkg.applicationInfo.uid);
- mProvidersByComponent.put(new ComponentName(p.info.packageName,
- p.info.name), p);
- ……
- }
- N = pkg.services.size();
- for (i=0; i<N; i++) {
- PackageParser.Service s = pkg.services.get(i);
- s.info.processName = fixProcessName(pkg.applicationInfo.processName,
- s.info.processName, pkg.applicationInfo.uid);
- mServices.addService(s);
- ……
- }
- N = pkg.receivers.size();
- r = null;
- for (i=0; i<N; i++) {
- PackageParser.Activity a = pkg.receivers.get(i);
- a.info.processName = fixProcessName(pkg.applicationInfo.processName,
- a.info.processName, pkg.applicationInfo.uid);
- mReceivers.addActivity(a, “receiver”);
- ……
- }
- N = pkg.activities.size();
- for (i=0; i<N; i++) {
- PackageParser.Activity a = pkg.activities.get(i);
- a.info.processName = fixProcessName(pkg.applicationInfo.processName,
- a.info.processName, pkg.applicationInfo.uid);
- mActivities.addActivity(a, “activity”);
- ……
- }
- ……
- }
- ……
- return pkg;
- }
- ……
- }
这个函数主要就是把前面解析应用程序得到的package、provider、service、receiver和activity等信息保存在PackageManagerService服务中了。
这样,在Android系统启动的时候安装应用程序的过程就介绍完了,但是,这些应用程序只是相当于在PackageManagerService服务注册好了,如果我们想要在Android桌面上看到这些应用程序,还需要有一个Home应用程序,负责从PackageManagerService服务中把这些安装好的应用程序取出来,并以友好的方式在桌面上展现出来,例如以快捷图标的形式。在Android系统中,负责把系统中已经安装的应用程序在桌面中展现出来的Home应用程序就是Launcher了,在下一篇文章中,我们将介绍Launcher是如何启动的以及它是如何从PackageManagerService服务中把系统中已经安装好的应用程序展现出来的,敬请期待。