相關文章鏈接：
1. Android Framework - 學習啓動篇
2. Android 系統服務 - PMS 的啓動過程
相關源碼文件：
frameworks/base/services/core/java/com/android/server/pm/PackageManagerService.java
frameworks/base/services/core/java/com/android/server/pm/PackageInstallerService.java
frameworks/base/services/core/java/com/android/server/pm/Settings.java
frameworks/base/services/core/java/com/android/server/SystemConfig
frameworks/base/core/java/android/content/pm/PackageManager.java
frameworks/base/core/android/java/content/pm/IPackageManager.aidl
frameworks/base/core/java/android/content/pm/PackageParser.java
frameworks/base/cmds/pm/src/com/android/commands/pm/Pm.java
frameworks/base/services/core/java/com/android/server/pm/Installer.java
frameworks/base/core/java/com/android/internal/os/InstallerConnection.java
PackageManagerService 也是 Android 應用開發者需要重點熟悉的一個服務，也是由 SystemService 進程創建的，管理着所有跟 package 相關的工作，常見的比如安裝、卸載應用。我們先找到其啓動創建的源代碼：
private void startBootstrapServices() {
// 啓動 installer 服務
Installer installer = mSystemServiceManager.startService(Installer.class);
...
// 處於加密狀態則僅僅解析核心應用
String cryptState = SystemProperties.get("vold.decrypt");
if (ENCRYPTING_STATE.equals(cryptState)) {
mOnlyCore = true; // ENCRYPTING_STATE = "trigger_restart_min_framework"
} else if (ENCRYPTED_STATE.equals(cryptState)) {
mOnlyCore = true; // ENCRYPTED_STATE = "1"
}
// 創建 PKMS 對象
mPackageManagerService = PackageManagerService.main(mSystemContext, installer,
mFactoryTestMode != FactoryTest.FACTORY_TEST_OFF, mOnlyCore);
mPackageManager = mSystemContext.getPackageManager();
}
SystemService 進程啓動過程中跟 PKMS 相關的有 installer 服務和 PackageManager 對象，我們主要分析他的創建過程也就是 PackageManagerService.main() 方法
public static PackageManagerService main(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
// 創建 PackageManagerService 對象
PackageManagerService m = new PackageManagerService(context, installer,
factoryTest, onlyCore);
// 將 PKMS 添加到 ServiceManager 進程去管理
ServiceManager.addService("package", m);
return m;
}
public PackageManagerService(Context context, Installer installer,
boolean factoryTest, boolean onlyCore) {
// 保存一些基本變量
mContext = context;
mFactoryTest = factoryTest;
mOnlyCore = onlyCore;
// 創建 Settings 對象
mSettings = new Settings(mPackages);
// 添加 system, phone, log, nfc, bluetooth, shell 這六種shareUserId到mSettings；
mSettings.addSharedUserLPw("android.uid.system", Process.SYSTEM_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.phone", RADIO_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.log", LOG_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.nfc", NFC_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.bluetooth", BLUETOOTH_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mSettings.addSharedUserLPw("android.uid.shell", SHELL_UID,
ApplicationInfo.FLAG_SYSTEM, ApplicationInfo.PRIVATE_FLAG_PRIVILEGED);
mInstaller = installer;
// 用來優化 dex
mPackageDexOptimizer = new PackageDexOptimizer(this);
synchronized (mInstallLock) {
synchronized (mPackages) {
// 創建名爲 “PackageManager” 的 handler 線程
mHandlerThread = new ServiceThread(TAG,
Process.THREAD_PRIORITY_BACKGROUND, true /*allowIo*/);
mHandlerThread.start();
mHandler = new PackageHandler(mHandlerThread.getLooper());
Watchdog.getInstance().addThread(mHandler, WATCHDOG_TIMEOUT);
// 創建各種目錄
File dataDir = Environment.getDataDirectory();
mAppDataDir = new File(dataDir, "data");
mAppInstallDir = new File(dataDir, "app");
mAppLib32InstallDir = new File(dataDir, "app-lib");
mAsecInternalPath = new File(dataDir, "app-asec").getPath();
mUserAppDataDir = new File(dataDir, "user");
mDrmAppPrivateInstallDir = new File(dataDir, "app-private");
// 創建用戶管理服務
sUserManager = new UserManagerService(context, this,
mInstallLock, mPackages);
// 這個目錄爲 /system/framework
File frameworkDir = new File(Environment.getRootDirectory(), "framework");
// 獲取到 frameworkDir 下面的所有文件
String[] frameworkFiles = frameworkDir.list();
if (frameworkFiles != null) {
for (String dexCodeInstructionSet : dexCodeInstructionSets) {
for (int i=0; i<frameworkFiles.length; i++) {
File libPath = new File(frameworkDir, frameworkFiles[i]);
String path = libPath.getPath();
// alreadyDexOpted 列表是否包含該文件
if (alreadyDexOpted.contains(path)) {
continue;
}
// 過濾掉不是 apk 和 jar 的文件
if (!path.endsWith(".apk") && !path.endsWith(".jar")) {
continue;
}
try {
int dexoptNeeded = DexFile.getDexOptNeeded(path, null, dexCodeInstructionSet, false);
if (dexoptNeeded != DexFile.NO_DEXOPT_NEEDED) {
// 執行 dexopt 優化操作
mInstaller.dexopt(path, Process.SYSTEM_UID, true, dexCodeInstructionSet, dexoptNeeded);
}
} catch (FileNotFoundException e) {
Slog.w(TAG, "Jar not found: " + path);
} catch (IOException e) {
Slog.w(TAG, "Exception reading jar: " + path, e);
}
}
}
}
// 蒐集解析系統各種 app 包信息
...
// 移除文件
mInstaller.moveFiles();
// 清理所有安裝不完整的包
ArrayList<PackageSetting> deletePkgsList = mSettings.getListOfIncompleteInstallPackagesLPr();
for(int i = 0; i < deletePkgsList.size(); i++) {
cleanupInstallFailedPackage(deletePkgsList.get(i));
}
// 刪除臨時文件
deleteTempPackageFiles();
// 處理解析非系統的 app
if (!mOnlyCore) {
// 掃描解析 /data/app 目錄
scanDirLI(mAppInstallDir, 0, scanFlags | SCAN_REQUIRE_KNOWN, 0);
// 掃描解析 /data/app-private 目錄
scanDirLI(mDrmAppPrivateInstallDir, PackageParser.PARSE_FORWARD_LOCK,
scanFlags | SCAN_REQUIRE_KNOWN, 0);
...
}
// 將所有解析的包信息寫到 packages.xml 文件
mSettings.writeLPr();
} // synchronized (mPackages)
} // synchronized (mInstallLock)
// 調用 gc
Runtime.getRuntime().gc();
}
PKMS 的創建和啓動過程比 AMS 複雜太多，我刪減了很多不是核心的代碼，總得來說 PKMS 在創建的過程中會去解析所有 apk 的安裝信息，其中包括系統應用和非系統的安裝應用，對於應用開發者來說，我們只需要關注非系統應用就足夠了。我們平時安裝的手機應用主要放在 mAppInstallDir(data/app) 目錄下。總的來說 PKMS 在啓動的時候會去解析我們手機所有的應用的 apk 包信息，並會將其所解析的內容全部保存在 mPackages 變量中，最後我們來看下 PKMS 到底是掃描解析保存了 apk 的哪些信息。
private void scanDirLI(File dir, int parseFlags, int scanFlags, long currentTime) {
...
for (File file : files) {
// 是不是 apk 文件
final boolean isPackage = (isApkFile(file) || file.isDirectory())
&& !PackageInstallerService.isStageName(file.getName());
if (!isPackage) {
// Ignore entries which are not packages
continue;
}
try {
// 掃描解析 apk 文件
scanPackageLI(file, parseFlags | PackageParser.PARSE_MUST_BE_APK,
scanFlags, currentTime, null);
} catch (PackageManagerException e) {
// 如果有異常，把這個文件或者文件夾刪除
if ((parseFlags & PackageParser.PARSE_IS_SYSTEM) == 0 &&
e.error == PackageManager.INSTALL_FAILED_INVALID_APK) {
logCriticalInfo(Log.WARN, "Deleting invalid package at " + file);
if (file.isDirectory()) {
mInstaller.rmPackageDir(file.getAbsolutePath());
} else {
file.delete();
}
}
}
}
}
private PackageParser.Package scanPackageLI(File scanFile, int parseFlags, int scanFlags,
long currentTime, UserHandle user) throws PackageManagerException {
// 創建一個解析對象
PackageParser pp = new PackageParser();
pp.setSeparateProcesses(mSeparateProcesses);
pp.setOnlyCoreApps(mOnlyCore);
pp.setDisplayMetrics(mMetrics);
final PackageParser.Package pkg;
try {
// 解析 apk 參數，返回 PackageParser.Package
pkg = pp.parsePackage(scanFile, parseFlags);
} catch (PackageParserException e) {
throw PackageManagerException.from(e);
}
// 蒐集證書信息
collectCertificatesLI(pp, ps, pkg, scanFile, parseFlags);
...
return scannedPkg;
}
public Package parsePackage(File packageFile, int flags) throws PackageParserException {
if (packageFile.isDirectory()) {
...
} else {
return parseMonolithicPackage(packageFile, flags);
}
}
public Package parseMonolithicPackage(File apkFile, int flags) throws PackageParserException {
final AssetManager assets = new AssetManager();
try {
final Package pkg = parseBaseApk(apkFile, assets, flags);
pkg.codePath = apkFile.getAbsolutePath();
return pkg;
} finally {
IoUtils.closeQuietly(assets);
}
}
private Package parseBaseApk(File apkFile, AssetManager assets, int flags)
throws PackageParserException {
final String apkPath = apkFile.getAbsolutePath();
final int cookie = loadApkIntoAssetManager(assets, apkPath, flags);
Resources res = null;
XmlResourceParser parser = null;
try {
res = new Resources(assets, mMetrics, null);
assets.setConfiguration(0, 0, null, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
Build.VERSION.RESOURCES_SDK_INT);
// 打開解析 AndroidManifest.xml 文件
parser = assets.openXmlResourceParser(cookie, ANDROID_MANIFEST_FILENAME);
final String[] outError = new String[1];
final Package pkg = parseBaseApk(res, parser, flags, outError);
if (pkg == null) {
throw new PackageParserException(mParseError,
apkPath + " (at " + parser.getPositionDescription() + "): " + outError[0]);
}
return pkg;
} catch (PackageParserException e) {
throw e;
} catch (Exception e) {
throw new PackageParserException(INSTALL_PARSE_FAILED_UNEXPECTED_EXCEPTION,
"Failed to read manifest from " + apkPath, e);
} finally {
IoUtils.closeQuietly(parser);
}
}
private Package parseBaseApk(Resources res, XmlResourceParser parser, int flags,
String[] outError) throws XmlPullParserException, IOException {
AttributeSet attrs = parser;
// 解析包名
try {
Pair<String, String> packageSplit = parsePackageSplitNames(parser, attrs, flags);
pkgName = packageSplit.first;
splitName = packageSplit.second;
} catch (PackageParserException e) {
mParseError = PackageManager.INSTALL_PARSE_FAILED_BAD_PACKAGE_NAME;
return null;
}
// 構建一個 Package 對象
final Package pkg = new Package(pkgName);
boolean foundApp = false;
// 獲取 VersionCode 和 VersionName
TypedArray sa = res.obtainAttributes(attrs,
com.android.internal.R.styleable.AndroidManifest);
pkg.mVersionCode = pkg.applicationInfo.versionCode = sa.getInteger(
com.android.internal.R.styleable.AndroidManifest_versionCode, 0);
pkg.mVersionName = sa.getNonConfigurationString(
com.android.internal.R.styleable.AndroidManifest_versionName, 0);
if (pkg.mVersionName != null) {
pkg.mVersionName = pkg.mVersionName.intern();
}
// 解析所有可能出現的屬性，application ，uses-permission，permission，等等
int outerDepth = parser.getDepth();
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG || parser.getDepth() > outerDepth)) {
if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
continue;
}
String tagName = parser.getName();
if (tagName.equals("application")) {
if (foundApp) {
if (RIGID_PARSER) {
outError[0] = "<manifest> has more than one <application>";
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return null;
} else {
Slog.w(TAG, "<manifest> has more than one <application>");
XmlUtils.skipCurrentTag(parser);
continue;
}
}
foundApp = true;
if (!parseBaseApplication(pkg, res, parser, attrs, flags, outError)) {
return null;
}
} else if (tagName.equals("permission")) {
if (parsePermission(pkg, res, parser, attrs, outError) == null) {
return null;
}
} else if (tagName.equals("uses-permission")) {
if (!parseUsesPermission(pkg, res, parser, attrs)) {
return null;
}
} else if (RIGID_PARSER) {
outError[0] = "Bad element under <manifest>: "
+ parser.getName();
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return null;
} else {
Slog.w(TAG, "Unknown element under <manifest>: " + parser.getName()
+ " at " + mArchiveSourcePath + " "
+ parser.getPositionDescription());
XmlUtils.skipCurrentTag(parser);
continue;
}
}
...
return pkg;
}
private boolean parseBaseApplication(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);
// 解析 application
String name = sa.getNonConfigurationString(
com.android.internal.R.styleable.AndroidManifestApplication_name, 0);
if (name != null) {
ai.className = buildClassName(pkgName, name, outError);
if (ai.className == null) {
sa.recycle();
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}
}
// 解析 allowBackup
boolean allowBackup = sa.getBoolean(
com.android.internal.R.styleable.AndroidManifestApplication_allowBackup, true);
if (allowBackup) {
...
}
// 解析 label 也就是 app 的名字
TypedValue v = sa.peekValue(
com.android.internal.R.styleable.AndroidManifestApplication_label);
if (v != null && (ai.labelRes=v.resourceId) == 0) {
ai.nonLocalizedLabel = v.coerceToString();
}
// 解析 icon ，logo，theme 等等
ai.icon = sa.getResourceId(
com.android.internal.R.styleable.AndroidManifestApplication_icon, 0);
ai.logo = sa.getResourceId(
com.android.internal.R.styleable.AndroidManifestApplication_logo, 0);
ai.banner = sa.getResourceId(
com.android.internal.R.styleable.AndroidManifestApplication_banner, 0);
ai.theme = sa.getResourceId(
com.android.internal.R.styleable.AndroidManifestApplication_theme, 0);
// 開始解析四大組件
final int innerDepth = parser.getDepth();
int type;
while ((type = parser.next()) != XmlPullParser.END_DOCUMENT
&& (type != XmlPullParser.END_TAG || parser.getDepth() > innerDepth)) {
if (type == XmlPullParser.END_TAG || type == XmlPullParser.TEXT) {
continue;
}
String tagName = parser.getName();
if (tagName.equals("activity")) {
Activity a = parseActivity(owner, res, parser, attrs, flags, outError, false,
owner.baseHardwareAccelerated);
if (a == null) {
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}
owner.activities.add(a);
} else if (tagName.equals("receiver")) {
Activity a = parseActivity(owner, res, parser, attrs, flags, outError, true, false);
if (a == null) {
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}
owner.receivers.add(a);
} else if (tagName.equals("service")) {
Service s = parseService(owner, res, parser, attrs, flags, outError);
if (s == null) {
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}
owner.services.add(s);
} else if (tagName.equals("provider")) {
Provider p = parseProvider(owner, res, parser, attrs, flags, outError);
if (p == null) {
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}
owner.providers.add(p);
} else if (tagName.equals("activity-alias")) {
Activity a = parseActivityAlias(owner, res, parser, attrs, flags, outError);
if (a == null) {
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}
owner.activities.add(a);
} else if (parser.getName().equals("meta-data")) {
// note: application meta-data is stored off to the side, so it can
// remain null in the primary copy (we like to avoid extra copies because
// it can be large)
if ((owner.mAppMetaData = parseMetaData(res, parser, attrs, owner.mAppMetaData,
outError)) == null) {
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}
} else if (tagName.equals("library")) {
sa = res.obtainAttributes(attrs,
com.android.internal.R.styleable.AndroidManifestLibrary);
// Note: don't allow this value to be a reference to a resource
// that may change.
String lname = sa.getNonResourceString(
com.android.internal.R.styleable.AndroidManifestLibrary_name);
sa.recycle();
if (lname != null) {
lname = lname.intern();
if (!ArrayUtils.contains(owner.libraryNames, lname)) {
owner.libraryNames = ArrayUtils.add(owner.libraryNames, lname);
}
}
XmlUtils.skipCurrentTag(parser);
} else if (tagName.equals("uses-library")) {
sa = res.obtainAttributes(attrs,
com.android.internal.R.styleable.AndroidManifestUsesLibrary);
// Note: don't allow this value to be a reference to a resource
// that may change.
String lname = sa.getNonResourceString(
com.android.internal.R.styleable.AndroidManifestUsesLibrary_name);
boolean req = sa.getBoolean(
com.android.internal.R.styleable.AndroidManifestUsesLibrary_required,
true);
sa.recycle();
if (lname != null) {
lname = lname.intern();
if (req) {
owner.usesLibraries = ArrayUtils.add(owner.usesLibraries, lname);
} else {
owner.usesOptionalLibraries = ArrayUtils.add(
owner.usesOptionalLibraries, lname);
}
}
XmlUtils.skipCurrentTag(parser);
} else if (tagName.equals("uses-package")) {
// Dependencies for app installers; we don't currently try to
// enforce this.
XmlUtils.skipCurrentTag(parser);
} else {
if (!RIGID_PARSER) {
Slog.w(TAG, "Unknown element under <application>: " + tagName
+ " at " + mArchiveSourcePath + " "
+ parser.getPositionDescription());
XmlUtils.skipCurrentTag(parser);
continue;
} else {
outError[0] = "Bad element under <application>: " + tagName;
mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;
return false;
}
}
}
return true;
}
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