本次源码基于Android11分析
PKMS的启动流程
packageManagerService作为系统的核心服务，其作用是：对应用进行安装、卸载和信息查询。此篇文章分析PKMS的启动流程，其启动流程大致如下：
关于PackageManagerService的类结构关系如下图所示：
PKMS的启动
PKMS作为系统的核心服务，也是从SystemServer进程中创建启动的，在其startBootstrapServices、startOtherServices两个方法中启动PKMS的服务。
public final class SystemServer implements Dumpable {
private void startBootstrapServices(@NonNull TimingsTraceAndSlog t) {
// 1. 启动Installer服务
Installer installer = mSystemServiceManager.startService(Installer.class);
// 2. 获取设备是否加密，加密则仅运行“核心”应用程序。
String cryptState = VoldProperties.decrypt().orElse("");
if (ENCRYPTING_STATE.equals(cryptState)) {
mOnlyCore = true;
} else if (ENCRYPTED_STATE.equals(cryptState)) {
mOnlyCore = true;
}
// 3. 调用PKMS.main ，实例化PKMS构造 (重点)
mPackageManagerService = PackageManagerService.main(mSystemContext, installer,
domainVerificationService, mFactoryTestMode != FactoryTest.FACTORY_TEST_OFF,
mOnlyCore);
// 4. 如果设备没有加密，操作它。管理A/B OTA dexopting
if (!mOnlyCore) {
OtaDexoptService.main(mSystemContext, mPackageManagerService);
}
}
private void startOtherServices(@NonNull TimingsTraceAndSlog t) {
if (!mOnlyCore) {
// 5. dex优化操作
mPackageManagerService.updatePackagesIfNeeded();
}
// 6. 磁盘优化维护操作
mPackageManagerService.performFstrimIfNeeded();
// 7. PKMS准备就绪
mPackageManagerService.systemReady();
}
}
在startBootstrapServices方法中关于PKMS主要做了四件事：
1.启动Installer服务
2.获取设备是否加密，加密则仅运行“核心”应用程序。
3.调用PKMS.main ，实例化PKMS构造 (重点)
4.如果设备没有加密，操作它。管理A/B OTA dexopting
其中第三点：调用PKMS.main会创建PKMS实例，并调用PKMS的构造函数，这也是耗时比较久的地方，也是重点分析的地方
在startOtherServices方法关于PKMS主要做了三件事：
1.dex优化操作
2.磁盘优化维护操作
3.PKMS准备就绪
其中dex优化操作也是比较耗时的操作
以上便是PKMS出生的启动的地方，其中最主要的是调用PKMS.main方法：
public static PackageManagerService main(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
// 检查Package编译相关系统属性
PackageManagerServiceCompilerMapping.checkProperties();
.....
//执行pkms构造方法
PackageManagerService m = new PackageManagerService(injector, onlyCore, factoryTest);
//启动部分应用服务于多用户场景
m.installWhitelistedSystemPackages();
//往ServiceManager中注册"package"和"package_native"
ServiceManager.addService("package", m);
final PackageManagerNative pmn = m.new PackageManagerNative();
ServiceManager.addService("package_native", pmn);
return m;
}
main()方法通过调用PackageManagerService的构造函数创建实例，并把PKMS实例向
ServiceManager中注册。PKMS的构造函数的代码很长，通过下小节分析它。
PKMS的构造函数
构造函数分为五个阶段，如下代码简易概括每个阶段的重点执行的事情：
public PackageManagerService(Injector injector, boolean onlyCore, boolean factoryTest) {
......
// 阶段一： 开始阶段
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_START,
SystemClock.uptimeMillis());
// 1. 构造 DisplayMetrics，保存分辨率相关信息
// 2. 创建Installer对象，与installd交互
// 3. 创建mPermissionManager对象，进行权限管理
// 4. 构造Settings类，保存安装包信息，清除路径不存在的孤立应用，主要涉及/data/system/目录的packages.xml, packages-backup.xml,packages.list,packages-stopped.xml,packages-stopped-backup.xml等文件。
// 5. 构造PackageDexOptimizer及DexManager类，处理dex优化
// 6. 创建SystemConfig实例，获取系统配置信息，配置共享lib库
// 7. 创建PackageManager的Handler线程，循环处理外部安装相关消息。
......
// 阶段二：系统扫描阶段
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SYSTEM_SCAN_START,
startTime);
// 1. 从init.rc中获取环境变量BOOTCLASSPATH和SYSTEMSERVERCLASSPATH；
// 2. 对于旧版本升级的情况，将安装时获取权限变更为运行时申请权限
// 3. 扫描system/vendor/product/odm/oem等目录的priv-app、app、overlay包
// 4. 清除安装时临时文件以及其他不必要的信息。
//扫描各个系统分区的的App
//解析系统App信息
//把解析结果存储起来，存储在PMS的相关属性和mSettings里
......
if (!mOnlyCore) {
// 阶段三： Data扫描阶段
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_DATA_SCAN_START,
SystemClock.uptimeMillis());
// 1. 扫描/data/app下的App，也就是用户安装的App
scanDirTracedLI(sAppInstallDir, 0, scanFlags | SCAN_REQUIRE_KNOWN, 0,
packageParser, executorService);
}
......
// 阶段四，扫描结束阶段
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_SCAN_END,
SystemClock.uptimeMillis());
// 1.sdk版本变更，更新权限
// 2.OTA升级后首次启动，清除不必要的缓存数据
// 3.权限等默认项更新完后，清理相关数据
// 4.更新package.xml
......
// 阶段五：就绪阶段
EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_READY,
SystemClock.uptimeMillis());
// 1. 创建PackageInstallerService对象
// 2. GC回收内存
}
阶段一：主要是解析了package.xml，获取已经安装的App信息，存储到Settings的mPackages中。并创建了工作线程和hanlder。
阶段二：扫描解析系统App,并把系统App信息存储在PKMS的相关属性和mSettings里
阶段三：对对/data/app路径扫描，此路径是用户安装的App
阶段四：对SDK版本进行检查更新，为系统核心服务准备存储空间、把更新后的信息写回对应的xml文件中。
阶段五：初始化PackageInstallerService
其中阶段三的扫描用户安装的app,是应该重点关注的，其调用scanDirTracedLI方法对App进行扫描解析。
PKMS的扫描流程
PKMS会扫描如下路径的App
// 系统App
/vendor/overlay
/product/overlay
/product_services/overlay
/odm/overlay
/oem/overlay
/system/framework
/system/priv-app
/system/app
/vendor/priv-app
/vendor/app
/odm/priv-app
/odm/app
/oem/app
/oem/priv-app
/product/priv-app
/product/app
/product_services/priv-app
/product_services/app
/product_services/priv-app
// 用户App
/data/app
private void scanDirTracedLI(File scanDir, final int parseFlags, int scanFlags,
long currentTime, PackageParser2 packageParser, ExecutorService executorService) {
Trace.traceBegin(TRACE_TAG_PACKAGE_MANAGER, "scanDir [" + scanDir.getAbsolutePath() + "]");
try {
// 调用scanDirLI
scanDirLI(scanDir, parseFlags, scanFlags, currentTime, packageParser, executorService);
} finally {
Trace.traceEnd(TRACE_TAG_PACKAGE_MANAGER);
}
}
private void scanDirLI(File scanDir, int parseFlags, int scanFlags, long currentTime,
PackageParser2 packageParser, ExecutorService executorService) {
final File[] files = scanDir.listFiles();
if (ArrayUtils.isEmpty(files)) {
Log.d(TAG, "No files in app dir " + scanDir);
return;
}
if (DEBUG_PACKAGE_SCANNING) {
Log.d(TAG, "Scanning app dir " + scanDir + " scanFlags=" + scanFlags
+ " flags=0x" + Integer.toHexString(parseFlags));
}
// ParallelPackageParser是一个队列，收集系统 apk 文件，
// 然后从这个队列里面一个个取出apk，调用PackageParser解析
ParallelPackageParser parallelPackageParser =
new ParallelPackageParser(packageParser, executorService);
// Submit files for parsing in parallel
int fileCount = 0;
for (File file : files) {
// 是 apk文件，或者是目录
final boolean isPackage = (isApkFile(file) || file.isDirectory())
&& !PackageInstallerService.isStageName(file.getName());
// 过滤掉非 apk 文件，如果不是则跳过继续扫描
if (!isPackage) {
// Ignore entries which are not packages
continue;
}
// 把 apk 信息存入ParallelPackageParser中的对象mQueue，
// parsePackage()函数赋予给了队列中的parsedPackage成员
parallelPackageParser.submit(file, parseFlags);
fileCount++;
}
// Process results one by one
for (; fileCount > 0; fileCount--) {
ParallelPackageParser.ParseResult parseResult = parallelPackageParser.take();
Throwable throwable = parseResult.throwable;
int errorCode = PackageManager.INSTALL_SUCCEEDED;
if (throwable == null) {
// TODO(toddke): move lower in the scan chain
// Static shared libraries have synthetic package names
if (parseResult.parsedPackage.isStaticSharedLibrary()) {
renameStaticSharedLibraryPackage(parseResult.parsedPackage);
}
try {
// 更新mSettings中相关包的数据
// 把包的信息存储到mPackages里面
addForInitLI(parseResult.parsedPackage, parseFlags, scanFlags,
currentTime, null);
} catch (PackageManagerException e) {
errorCode = e.error;
Slog.w(TAG, "Failed to scan " + parseResult.scanFile + ": " + e.getMessage());
}
} else if (throwable instanceof PackageParserException) {
PackageParserException e = (PackageParserException)
throwable;
errorCode = e.error;
Slog.w(TAG, "Failed to parse " + parseResult.scanFile + ": " + e.getMessage());
} else {
throw new IllegalStateException("Unexpected exception occurred while parsing "
+ parseResult.scanFile, throwable);
}
if ((scanFlags & SCAN_AS_APK_IN_APEX) != 0 && errorCode != INSTALL_SUCCEEDED) {
mApexManager.reportErrorWithApkInApex(scanDir.getAbsolutePath());
}
// 如果是非系统 apk 并且解析失败
if ((scanFlags & SCAN_AS_SYSTEM) == 0
&& errorCode != PackageManager.INSTALL_SUCCEEDED) {
logCriticalInfo(Log.WARN,
"Deleting invalid package at " + parseResult.scanFile);
// 非系统 Package 扫描失败，删除文件
removeCodePathLI(parseResult.scanFile);
}
}
}
scanDirLI方法：遍历目录下所有文件，如果文件不是Apk或目录则不扫描，之后调用ParallelPackageParser.submit。如果非系统的App没有解析失败将被删除。
public void submit(File scanFile, int parseFlags) {
mExecutorService.submit(() -> {
ParseResult pr = new ParseResult();
Trace.traceBegin(TRACE_TAG_PACKAGE_MANAGER, "parallel parsePackage [" + scanFile + "]");
try {
pr.scanFile = scanFile;
// 通过parsePackage()方法解析
pr.parsedPackage = parsePackage(scanFile, parseFlags);
} catch (Throwable e) {
pr.throwable = e;
} finally {
Trace.traceEnd(TRACE_TAG_PACKAGE_MANAGER);
}
try {
// 将ParseResult加入到mQueue队列
mQueue.put(pr);
} catch (InterruptedException e) {
Thread.currentThread().interrupt();
// Propagate result to callers of take().
// This is helpful to prevent main thread from getting stuck waiting on
// ParallelPackageParser to finish in case of interruption
mInterruptedInThread = Thread.currentThread().getName();
}
});
}
protected ParsedPackage parsePackage(File scanFile, int parseFlags)
throws PackageParser.PackageParserException {
// 调用 PackageParser2.parsePackage方法
return mPackageParser.parsePackage(scanFile, parseFlags, true);
}
通过
PackageParser2.parsePackage解析Apk文件
// PackageParser2
public ParsedPackage parsePackage(File packageFile, int flags, boolean useCaches)
throws PackageParserException {
......
// 调用ParsingPackageUtils.parsePackage进行解析
ParseResult result = parsingUtils.parsePackage(input, packageFile, flags);
......
ParsedPackage parsed = (ParsedPackage) result.getResult().hideAsParsed();
return parsed;
}
//ParsingPackageUtils
public ParseResult parsePackage(ParseInput input, File packageFile,
int flags)
throws PackageParserException {
// 如果是目录，调用parseClusterPackage
if (packageFile.isDirectory()) {
return parseClusterPackage(input, packageFile, flags);
} else {
// 如果是apk，调用parseMonolithicPackage
return parseMonolithicPackage(input, packageFile, flags);
}
}
如果是目录调用
parseClusterPackage方法,如果是apk文件调用parseMonolithicPackage方法
private ParseResult parseClusterPackage(ParseInput input, File packageDir,
int flags) {
// 获取应用目录的PackageLite对象，这个对象分开保存了目录下的核心应用和非核心应用的名称
ParseResult liteResult =
ApkLiteParseUtils.parseClusterPackageLite(input, packageDir, 0);
if (liteResult.isError()) {
return input.error(liteResult);
}
final PackageParser.PackageLite lite = liteResult.getResult();
// 如果lite中没有核心应用，退出
if (mOnlyCoreApps && !lite.coreApp) {
return input.error(INSTALL_PARSE_FAILED_ONLY_COREAPP_ALLOWED,
"Not a coreApp: " + packageDir);
}
// Build the split dependency tree.
SparseArray splitDependencies = null;
final SplitAssetLoader assetLoader;
if (lite.isolatedSplits && !ArrayUtils.isEmpty(lite.splitNames)) {
try {
splitDependencies = SplitAssetDependencyLoader.createDependenciesFromPackage(lite);
assetLoader = new SplitAssetDependencyLoader(lite, splitDependencies, flags);
} catch (SplitAssetDependencyLoader.IllegalDependencyException e) {
return input.error(INSTALL_PARSE_FAILED_BAD_MANIFEST, e.getMessage());
}
} else {
assetLoader = new DefaultSplitAssetLoader(lite, flags);
}
try {
final AssetManager assets = assetLoader.getBaseAssetManager();
final File baseApk = new File(lite.baseCodePath);
// 对核心应用进行解析
ParseResult result = parseBaseApk(input, baseApk,
lite.codePath, assets, flags);
if (result.isError()) {
return input.error(result);
}
ParsingPackage pkg = result.getResult();
if (!ArrayUtils.isEmpty(lite.splitNames)) {
pkg.asSplit(
lite.splitNames,
lite.splitCodePaths,
lite.splitRevisionCodes,
splitDependencies
);
final int num = lite.splitNames.length;
for (int i = 0; i < num; i++) {
final AssetManager splitAssets = assetLoader.getSplitAssetManager(i);
// 对非核心应用的处理
parseSplitApk(input, pkg, i, splitAssets, flags);
}
}
pkg.setUse32BitAbi(lite.use32bitAbi);
return input.success(pkg);
} catch (PackageParserException e) {
return input.error(INSTALL_PARSE_FAILED_UNEXPECTED_EXCEPTION,
"Failed to load assets: " + lite.baseCodePath, e);
} finally {
IoUtils.closeQuietly(assetLoader);
}
}
private ParseResult parseMonolithicPackage(ParseInput input, File apkFile,
int flags) throws PackageParserException {
ParseResult liteResult =
ApkLiteParseUtils.parseMonolithicPackageLite(input, apkFile, flags);
if (liteResult.isError()) {
return input.error(liteResult);
}
final PackageParser.PackageLite lite = liteResult.getResult();
if (mOnlyCoreApps && !lite.coreApp) {
return input.error(INSTALL_PARSE_FAILED_ONLY_COREAPP_ALLOWED,
"Not a coreApp: " + apkFile);
}
final SplitAssetLoader assetLoader = new DefaultSplitAssetLoader(lite, flags);
try {
// 对核心应用解析
ParseResult result = parseBaseApk(input,
apkFile,
apkFile.getCanonicalPath(),
assetLoader.getBaseAssetManager(), flags);
if (result.isError()) {
return input.error(result);
}
return input.success(result.getResult()
.setUse32BitAbi(lite.use32bitAbi));
} catch (IOException e) {
return input.error(INSTALL_PARSE_FAILED_UNEXPECTED_EXCEPTION,
"Failed to get path: " + apkFile, e);
} finally {
IoUtils.closeQuietly(assetLoader);
}
}
无论文件是目录还是apk，都会调用
parseBaseApk方法,从parseBaseApk方法开始解析AndroidManifest.xml文件
private ParseResult parseBaseApk(ParseInput input, File apkFile,
String codePath, AssetManager assets, int flags) {
final String apkPath = apkFile.getAbsolutePath();
String volumeUuid = null;
if (apkPath.startsWith(PackageParser.MNT_EXPAND)) {
final int end = apkPath.indexOf('/', PackageParser.MNT_EXPAND.length());
volumeUuid = apkPath.substring(PackageParser.MNT_EXPAND.length(), end);
}
if (PackageParser.DEBUG_JAR) Slog.d(TAG, "Scanning base APK: " + apkPath);
final int cookie = assets.findCookieForPath(apkPath);
if (cookie == 0) {
return input.error(INSTALL_PARSE_FAILED_BAD_MANIFEST,
"Failed adding asset path: " + apkPath);
}
// assets.openXmlResourceParser(...)。获得一个 XML 资源解析对象，
try (XmlResourceParser parser = assets.openXmlResourceParser(cookie,
PackageParser.ANDROID_MANIFEST_FILENAME)) {
final Resources res = new Resources(assets, mDisplayMetrics, null);
// 再调用重载函数parseBaseApk
ParseResult result = parseBaseApk(input, apkPath, codePath, res,
parser, flags);
if (result.isError()) {
return input.error(result.getErrorCode(),
apkPath + " (at " + parser.getPositionDescription() + "): "
+ result.getErrorMessage());
}
final ParsingPackage pkg = result.getResult();
if (assets.containsAllocatedTable()) {
final ParseResult deferResult = input.deferError(
"Targeting R+ (version " + Build.VERSION_CODES.R + " and above) requires"
+ " the resources.arsc of installed APKs to be stored uncompressed"
+ " and aligned on a 4-byte boundary",
DeferredError.RESOURCES_ARSC_COMPRESSED);
if (deferResult.isError()) {
return input.error(INSTALL_PARSE_FAILED_RESOURCES_ARSC_COMPRESSED,
deferResult.getErrorMessage());
}
}
ApkAssets apkAssets = assets.getApkAssets()[0];
if (apkAssets.definesOverlayable()) {
SparseArray packageNames = assets.getAssignedPackageIdentifiers();
int size = packageNames.size();
for (int index = 0; index < size; index++) {
String packageName = packageNames.get(index);
Map overlayableToActor = assets.getOverlayableMap(packageName);
if (overlayableToActor != null && !overlayableToActor.isEmpty()) {
for (String overlayable : overlayableToActor.keySet()) {
pkg.addOverlayable(overlayable, overlayableToActor.get(overlayable));
}
}
}
}
pkg.setVolumeUuid(volumeUuid);
if ((flags & PackageParser.PARSE_COLLECT_CERTIFICATES) != 0) {
pkg.setSigningDetails(getSigningDetails(pkg, false));
} else {
pkg.setSigningDetails(SigningDetails.UNKNOWN);
}
return input.success(pkg);
} catch (Exception e) {
return input.error(INSTALL_PARSE_FAILED_UNEXPECTED_EXCEPTION,
"Failed to read manifest from " + apkPath, e);
}
}
private ParseResult parseBaseApk(ParseInput input, String apkPath,
String codePath, Resources res, XmlResourceParser parser, int flags)
throws XmlPullParserException, IOException, PackageParserException {
final String splitName;
final String pkgName;
ParseResult> packageSplitResult =
ApkLiteParseUtils.parsePackageSplitNames(input, parser, parser);
if (packageSplitResult.isError()) {
return input.error(packageSplitResult);
}
Pair packageSplit = packageSplitResult.getResult();
pkgName = packageSplit.first;
splitName = packageSplit.second;
if (!TextUtils.isEmpty(splitName)) {
return input.error(
PackageManager.INSTALL_PARSE_FAILED_BAD_PACKAGE_NAME,
"Expected base APK, but found split " + splitName
);
}
// AndroidManifest
final TypedArray manifestArray = res.obtainAttributes(parser, R.styleable.AndroidManifest);
try {
final boolean isCoreApp =
parser.getAttributeBooleanValue(null, "coreApp", false);
final ParsingPackage pkg = mCallback.startParsingPackage(
pkgName, apkPath, codePath, manifestArray, isCoreApp);
// 调用parseBaseApkTags()
final ParseResult result =
parseBaseApkTags(input, pkg, manifestArray, res, parser, flags);
if (result.isError()) {
return result;
}
return input.success(pkg);
} finally {
manifestArray.recycle();
}
}
private ParseResult parseBaseApkTags(ParseInput input, ParsingPackage pkg,
TypedArray sa, Resources res, XmlResourceParser parser, int flags)
throws XmlPullParserException, IOException {
ParseResult sharedUserResult = parseSharedUser(input, pkg, sa);
if (sharedUserResult.isError()) {
return sharedUserResult;
}
pkg.setInstallLocation(anInteger(PackageParser.PARSE_DEFAULT_INSTALL_LOCATION,
R.styleable.AndroidManifest_installLocation, sa))
.setTargetSandboxVersion(anInteger(PackageParser.PARSE_DEFAULT_TARGET_SANDBOX,
R.styleable.AndroidManifest_targetSandboxVersion, sa))
/* Set the global "on SD card" flag */
.setExternalStorage((flags & PackageParser.PARSE_EXTERNAL_STORAGE) != 0);
boolean foundApp = false;
final int depth = parser.getDepth();
int type;
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG
|| parser.getDepth() > depth)) {
if (type != XmlPullParser.START_TAG) {
continue;
}
String tagName = parser.getName();
final ParseResult result;
// TODO(b/135203078): Convert to instance methods to share variables
// has special logic, so it's handled outside the general method
// 判断是是否是Application标签
if (PackageParser.TAG_APPLICATION.equals(tagName)) {
if (foundApp) {
if (PackageParser.RIGID_PARSER) {
result = input.error(" has more than one ");
} else {
Slog.w(TAG, " has more than one ");
result = input.success(null);
}
} else {
foundApp = true;
// 是application标签，调用parseBaseApplication方法，解析application
result = parseBaseApplication(input, pkg, res, parser, flags);
}
} else {
// 如果不是application标签，调用parseBaseApkTag方法，解析核心应用的所有tag
result = parseBaseApkTag(tagName, input, pkg, res, parser, flags);
}
if (result.isError()) {
return input.error(result);
}
}
if (!foundApp && ArrayUtils.size(pkg.getInstrumentations()) == 0) {
ParseResult deferResult = input.deferError(
" does not contain an or ",
DeferredError.MISSING_APP_TAG);
if (deferResult.isError()) {
return input.error(deferResult);
}
}
if (!ParsedAttribution.isCombinationValid(pkg.getAttributions())) {
return input.error(
INSTALL_PARSE_FAILED_BAD_MANIFEST,
"Combination tags are not valid"
);
}
convertNewPermissions(pkg);
convertSplitPermissions(pkg);
// At this point we can check if an application is not supporting densities and hence
// cannot be windowed / resized. Note that an SDK version of 0 is common for
// pre-Doughnut applications.
if (pkg.getTargetSdkVersion() < DONUT
|| (!pkg.isSupportsSmallScreens()
&& !pkg.isSupportsNormalScreens()
&& !pkg.isSupportsLargeScreens()
&& !pkg.isSupportsExtraLargeScreens()
&& !pkg.isResizeable()
&& !pkg.isAnyDensity())) {
adjustPackageToBeUnresizeableAndUnpipable(pkg);
}
return input.success(pkg);
}
private ParseResult parseBaseApplication(ParseInput input,
ParsingPackage pkg, Resources res, XmlResourceParser parser, int flags)
throws XmlPullParserException, IOException {
......
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG
|| parser.getDepth() > depth)) {
if (type != XmlPullParser.START_TAG) {
continue;
}
final ParseResult result;
// 获取 "application" 子标签的标签内容
String tagName = parser.getName();
boolean isActivity = false;
switch (tagName) {
// 如果标签是 "activity"
case "activity":
isActivity = true;
// fall-through
case "receiver":
// 如果标签是 "receiver"，获取receiver信息
ParseResult activityResult =
ParsedActivityUtils.parseActivityOrReceiver(mSeparateProcesses, pkg,
res, parser, flags, PackageParser.sUseRoundIcon, input);
if (activityResult.isSuccess()) {
ParsedActivity activity = activityResult.getResult();
if (isActivity) {
hasActivityOrder |= (activity.getOrder() != 0);
pkg.addActivity(activity);
} else {
hasReceiverOrder |= (activity.getOrder() != 0);
pkg.addReceiver(activity);
}
}
result = activityResult;
break;
case "service":
// 解析 "service"
ParseResult serviceResult =
ParsedServiceUtils.parseService(mSeparateProcesses, pkg, res, parser,
flags, PackageParser.sUseRoundIcon, input);
if (serviceResult.isSuccess()) {
ParsedService service = serviceResult.getResult();
hasServiceOrder |= (service.getOrder() != 0);
pkg.addService(service);
}
result = serviceResult;
break;
case "provider":
// 解析 "provider"
ParseResult providerResult =
ParsedProviderUtils.parseProvider(mSeparateProcesses, pkg, res, parser,
flags, PackageParser.sUseRoundIcon, input);
if (providerResult.isSuccess()) {
pkg.addProvider(providerResult.getResult());
}
result = providerResult;
break;
case "activity-alias":
// 解析 "activity-alias"
activityResult = ParsedActivityUtils.parseActivityAlias(pkg, res,
parser, PackageParser.sUseRoundIcon, input);
if (activityResult.isSuccess()) {
ParsedActivity activity = activityResult.getResult();
hasActivityOrder |= (activity.getOrder() != 0);
pkg.addActivity(activity);
}
result = activityResult;
break;
default:
result = parseBaseAppChildTag(input, tagName, pkg, res, parser, flags);
break;
}
if (result.isError()) {
return input.error(result);
}
}
if (TextUtils.isEmpty(pkg.getStaticSharedLibName())) {
// Add a hidden app detail activity to normal apps which forwards user to App Details
// page.
ParseResult a = generateAppDetailsHiddenActivity(input, pkg);
if (a.isError()) {
// Error should be impossible here, as the only failure case as of SDK R is a
// string validation error on a constant ":app_details" string passed in by the
// parsing code itself. For this reason, this is just a hard failure instead of
// deferred.
return input.error(a);
}
pkg.addActivity(a.getResult());
}
if (hasActivityOrder) {
pkg.sortActivities();
}
if (hasReceiverOrder) {
pkg.sortReceivers();
}
if (hasServiceOrder) {
pkg.sortServices();
}
// Must be run after the entire {@link ApplicationInfo} has been fully processed and after
// every activity info has had a chance to set it from its attributes.
setMaxAspectRatio(pkg);
setMinAspectRatio(pkg);
setSupportsSizeChanges(pkg);
pkg.setHasDomainUrls(hasDomainURLs(pkg));
return input.success(pkg);
}
parseBaseApk方法开始解析AndroidManifest.xml文件，parseBaseApkTags方法中将application标签和其他标签分开处理，如果是application标签则里面定义了四大组件，通过parseBaseApplication方法对application标签进行解析。
App通过解析后，要对信息进行保存，则调用PKMS. addForInitLI
private AndroidPackage addForInitLI(ParsedPackage parsedPackage,
@ParseFlags int parseFlags, @ScanFlags int scanFlags, long currentTime,
@Nullable UserHandle user)
throws PackageManagerException {
// 判断系统应用是否需要更新
synchronized (mLock) {
if (scanSystemPartition) {
if (isSystemPkgUpdated) {
//......
}
}
}
if (isSystemPkgBetter) {
// 更新安装包到 system 分区中
synchronized (mLock) {
// just remove the loaded entries from package lists
mPackages.remove(pkgSetting.name);
}
// 创建安装参数 InstallArgs
final InstallArgs args = createInstallArgsForExisting(
pkgSetting.codePathString,
pkgSetting.resourcePathString, getAppDexInstructionSets(
pkgSetting.primaryCpuAbiString, pkgSetting.secondaryCpuAbiString));
args.cleanUpResourcesLI();
synchronized (mLock) {
mSettings.enableSystemPackageLPw(pkgSetting.name);
}
}
// 安装包校验
collectCertificatesLI(pkgSetting, parsedPackage, forceCollect, skipVerify);
try (@SuppressWarnings("unused") PackageFreezer freezer = freezePackage(
parsedPackage.getPackageName(),
"scanPackageInternalLI")) {
// 如果两个apk签名不匹配，则调用 deletePackageLIF 方法清除 apk 文件及其数据
deletePackageLIF(parsedPackage.getPackageName(), null, true, null, 0, null,
false, null);
}
pkgSetting = null;
} else if (newPkgVersionGreater) {
// 更新系统 apk 程序
InstallArgs args = createInstallArgsForExisting(
pkgSetting.codePathString,
pkgSetting.resourcePathString, getAppDexInstructionSets(
pkgSetting.primaryCpuAbiString, pkgSetting.secondaryCpuAbiString));
synchronized (mInstallLock) {
args.cleanUpResourcesLI();
}
}
}
// 如果新安装的系统 app 会被旧的 APP 数据覆盖，所以需要隐藏系统应用程序，并重新扫描 /data/app 目录
if (shouldHideSystemApp) {
synchronized (mLock) {
mSettings.disableSystemPackageLPw(parsedPackage.getPackageName(), true);
}
}
return scanResult.pkgSetting.pkg;
}
总结：
PKMS的启动流程：在SystemServer进程中启动 PKMS，通过调用PKMS的构造函数遍历系统App和非系统App进行解析对AndroidManifest.xml的结点进行解析，然后将解析结果进行保存更新。