从源码角度解析Android中APK的安装过程
1. Android中APK简介
Android应用Apk的安装有如下四种方式：
1.1 系统应用安装
没有安装界面，在开机时自动完成
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1.2 网络下载应用安装
没有安装界面，在应用市场完成
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1.3 ADB命令安装
没有安装界面，通过命令直接安装
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1.4 外部设备安装
有安装界面，通过SD卡等外部设备安装，由packageInstaller处理安装逻辑
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2. APK安装涉及到的几个常用目录
system/app ： 系统自带的应用程序，获得root权限才能删除
data/app ： 用户程序安装目录，安装时会把apk文件复制到此目录下
data/data ： 存放应用程序的数据
data/dalvik-cache ： 将apk中的dex文件安装到该目录下（dex文件是dalvik虚拟机的可执行文件，大小约为原始apk的四分之一）
3. APK安装的四大步骤
（1）拷贝apk到指定的目录
默认情况下，用户安装的apk首先会拷贝到/data/app下，用户有访问/data/app目录的权限，但系统出厂的apk文件
会被放到/system分区下，包括/system/app，/system/vendor/app，以及/system/priv-app等。该分区需要
root权限的用户才能访问。
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（2）加压apk、拷贝文件、创建应用的数据目录
为了加快APP的启动速度，apk在安装的时候，会首先将APP的可执行文件（dex）拷贝到/data/dalvik-cache目录
下，缓存起来。再在/data/data/目录下创建应用程序的数据目录（以应用包名命令），用来存放应用的数据库、xml
文件、cache、二进制的so动态库等。
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（3）解析apk的AndroidManifest.xml文件
在安装apk的过程中，会解析apk的AndroidManifest.xml文件，将apk的权限、应用包名、apk的安装位置、版本、
userID等重要信息保存在/data/system/packages.xml文件中。这些操作都是在PackageManagerService中完成
的。
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（4）显示icon图标
应用程序经过PMS中的逻辑处理后，相当于已经注册好了，如果想要在Android桌面上看到icon图标，则需要
Launcher将系统中已经安装的程序展现在桌面上。
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4. APK安装的预备知识点
（1）PackageManagerService是由SystemServer启动，PMS负责应用的安装、卸载、权限检查等工作
（2）在/system/app和/data/app目录下的apk文件，PMS在启动过程中，都会扫描安装
（3）每次开机时，PMS都会在构造函数中对指定目录下的apk进行扫描，没有安装的apk就会触发安装。
(4) 本文的源码是基于Android6.0
5. 系统应用安装
在创建PackageManagerService实例时，会在PMS的构造函数中开始执行安装应用程序的逻辑。在PMS的构造函数中做了如下几点重要操作。
（1）创建Settings对象，添加shareUserId
mSettings = new Settings(mPackages);
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);
(2)通过PackageManagerService构造函数参数获取应用安装器Installer
mInstaller = installer;
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(3)获取SystemConfig实例，读取“/system/etc/permissions/*.xml”资源文件
从资源文件中获取mGlobalsGids(Group-ids)、mSystemPermissions(系统权限)、mAvailableFeatures(系统支持的features)属性。
SystemConfig systemConfig = SystemConfig.getInstance();
mGlobalGids = systemConfig.getGlobalGids();
mSystemPermissions = systemConfig.getSystemPermissions();
mAvailableFeatures = systemConfig.getAvailableFeatures();
(4)创建系统消息处理线程
mHandlerThread = new ServiceThread(TAG,Process.THREAD_PRIORITY_BACKGROUND, true /*allowIo*/);
mHandlerThread.start();
mHandler = new PackageHandler(mHandlerThread.getLooper());
Watchdog.getInstance().addThread(mHandler, WATCHDOG_TIMEOUT);
(5)执行com.android.server.pm.Settings中的readLPw方法，读取安装包中的信息，并解析成对应的数据结构。
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");
sUserManager = new UserManagerService(context, this,
mInstallLock, mPackages);
// Propagate permission configuration in to package manager.
ArrayMap
= systemConfig.getPermissions();
for (int i=0; i
BasePermission bp = mSettings.mPermissions.get(perm.name);
if (bp == null) {
bp = new BasePermission(perm.name, "android", BasePermission.TYPE_BUILTIN);
mSettings.mPermissions.put(perm.name, bp);
}
if (perm.gids != null) {
bp.setGids(perm.gids, perm.perUser);
}
}
ArrayMap
for (int i=0; i
new SharedLibraryEntry(libConfig.valueAt(i), null));
}
mFoundPolicyFile = SELinuxMMAC.readInstallPolicy();
mRestoredSettings = mSettings.readLPw(this, sUserManager.getUsers(false),
mSdkVersion, mOnlyCore);
其中，读取的重要文件有如下几个：
packages.xml：记录了系统中所有安装应用的信息，包括基本信息、签名和权限。
packages-backup.xml：packages.xml的备份文件
packages.list：保存普通应用的数据目录和uid等信息
packages-stopped.xml：记录系统中被强制停止运行应用的信息。系统在强制停止某个应用时，会将应用的信息记录到该文件中
packages-stopped-backup.xml：packages-stopped.xml的备份文件
这几个目录在创建Settings对象时就已经被封装成了对应的File文件。
(6)执行PMS中的scanDirLI方法扫描系统安装目录和非系统apk信息
File vendorOverlayDir = new File(VENDOR_OVERLAY_DIR);
scanDirLI(vendorOverlayDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR, scanFlags | SCAN_TRUSTED_OVERLAY, 0);
// Find base frameworks (resource packages without code).
scanDirLI(frameworkDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR
| PackageParser.PARSE_IS_PRIVILEGED,
scanFlags | SCAN_NO_DEX, 0);
// Collected privileged system packages.
final File privilegedAppDir = new File(Environment.getRootDirectory(), "priv-app");
scanDirLI(privilegedAppDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR
| PackageParser.PARSE_IS_PRIVILEGED, scanFlags, 0);
// Collect ordinary system packages.
final File systemAppDir = new File(Environment.getRootDirectory(), "app");
scanDirLI(systemAppDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR, scanFlags, 0);
// Collect all vendor packages.
File vendorAppDir = new File("/vendor/app");
try {
vendorAppDir = vendorAppDir.getCanonicalFile();
} catch (IOException e) {
// failed to look up canonical path, continue with original one
}
scanDirLI(vendorAppDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR, scanFlags, 0);
// Collect all OEM packages.
final File oemAppDir = new File(Environment.getOemDirectory(), "app");
scanDirLI(oemAppDir, PackageParser.PARSE_IS_SYSTEM
| PackageParser.PARSE_IS_SYSTEM_DIR, scanFlags, 0);
其中，系统安装目录有：
/system/framework 系统库
/system/app 默认的系统应用
/vendor/app 厂商定制的应用
非系统apk信息目录：
/data/app/
/system/priv-app/
/data/app-private/
到此为止，PMS构造函数中主要的逻辑操作就介绍完了。
继续探究扫描安装过程：
（1）深入到PackageManagerService—>scanDirLI方法中
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;
}
if (DEBUG_PACKAGE_SCANNING) {
Log.d(TAG, "Scanning app dir " + dir + " scanFlags=" + scanFlags
+ " flags=0x" + Integer.toHexString(parseFlags));
}
for (File file : files) {
final boolean isPackage = (isApkFile(file) || file.isDirectory())
&& !PackageInstallerService.isStageName(file.getName());
if (!isPackage) {
// Ignore entries which are not packages
continue;
}
try {
scanPackageLI(file, parseFlags | PackageParser.PARSE_MUST_BE_APK,
scanFlags, currentTime, null);//注释1
} catch (PackageManagerException e) {
Slog.w(TAG, "Failed to parse " + file + ": " + e.getMessage());
// Delete invalid userdata apps
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();
}
}
}
}
}
注释1处，对于目录中的每一个文件，如果是已apk作为后缀名的，就会调用PackageManagerService—>scanPackageLI方法进行扫描解析
(2)深入到PackageManagerService—>scanPackageLI方法中
private PackageParser.Package scanPackageLI(File scanFile, int parseFlags, int scanFlags,
long currentTime, UserHandle user) throws PackageManagerException {
if (DEBUG_INSTALL) Slog.d(TAG, "Parsing: " + scanFile);
parseFlags |= mDefParseFlags;
PackageParser pp = new PackageParser();//注释1
pp.setSeparateProcesses(mSeparateProcesses);
pp.setOnlyCoreApps(mOnlyCore);
pp.setDisplayMetrics(mMetrics);
if ((scanFlags & SCAN_TRUSTED_OVERLAY) != 0) {
parseFlags |= PackageParser.PARSE_TRUSTED_OVERLAY;
}
final PackageParser.Package pkg;
try {
pkg = pp.parsePackage(scanFile, parseFlags);//注释2
} catch (PackageParserException e) {
throw PackageManagerException.from(e);
}
......省略......
// reader
synchronized (mPackages) {//注释3
// Look to see if we already know about this package.
String oldName = mSettings.mRenamedPackages.get(pkg.packageName);
if (pkg.mOriginalPackages != null && pkg.mOriginalPackages.contains(oldName)) {
// This package has been renamed to its original name. Let's
// use that.
ps = mSettings.peekPackageLPr(oldName);
}
// If there was no original package, see one for the real package name.
if (ps == null) {
ps = mSettings.peekPackageLPr(pkg.packageName);
}
// Check to see if this package could be hiding/updating a system
// package. Must look for it either under the original or real
// package name depending on our state.
updatedPkg = mSettings.getDisabledSystemPkgLPr(ps != null ? ps.name : pkg.packageName);
if (DEBUG_INSTALL && updatedPkg != null) Slog.d(TAG, "updatedPkg = " + updatedPkg);
}
......省略......
PackageParser.Package scannedPkg = scanPackageLI(pkg, parseFlags, scanFlags
| SCAN_UPDATE_SIGNATURE, currentTime, user);//注释4
/*
* If the system app should be overridden by a previously installed
* data, hide the system app now and let the /data/app scan pick it up
* again.
*/
if (shouldHideSystemApp) {
synchronized (mPackages) {
mSettings.disableSystemPackageLPw(pkg.packageName);
}
}
return scannedPkg;
}
注释1处：创建一个PackageParser实例。
注释2处调用PackageParser的parsePackage函数来对apk安装包的AndroidManifest.xml文件扫描和提取证书信息，然后构建一个PackageParser.Package对象，并将其返回。
注释3将解析返回的PackageParser对象中的信息保存到PMS中。
注释4调用另一个重载的scanPackageLI方法来构建一个PackageSetting对象，这个对象保存的信息最后会通过writeLPr写入到/data/system/packages.xml文件中去。
(3)根据（2）中注释2深入到PackageParser—>parsePackage方法中
public Package parsePackage(File packageFile, int flags) throws PackageParserException {
if (packageFile.isDirectory()) {
return parseClusterPackage(packageFile, flags);
} else {
return parseMonolithicPackage(packageFile, flags);
}
}
这里根据packageFile是否是目录分别调用parseClusterPackage和parseMonolithicPackage去解析。
其中parseClusterPackage方法如下：
private Package parseClusterPackage(File packageDir, int flags) throws PackageParserException {
final PackageLite lite = parseClusterPackageLite(packageDir, 0);
if (mOnlyCoreApps && !lite.coreApp) {
throw new PackageParserException(INSTALL_PARSE_FAILED_MANIFEST_MALFORMED,
"Not a coreApp: " + packageDir);
}
final AssetManager assets = new AssetManager();
try {
...省略...
final File baseApk = new File(lite.baseCodePath);
final Package pkg = parseBaseApk(baseApk, assets, flags);//注释1
if (pkg == null) {
throw new PackageParserException(INSTALL_PARSE_FAILED_NOT_APK,
"Failed to parse base APK: " + baseApk);
}
...省略...
pkg.codePath = packageDir.getAbsolutePath();
return pkg;
} finally {
IoUtils.closeQuietly(assets);
}
}
parseMonolithicPackage方法如下：
public Package parseMonolithicPackage(File apkFile, int flags) throws PackageParserException {
...省略...
final AssetManager assets = new AssetManager();
try {
final Package pkg = parseBaseApk(apkFile, assets, flags);//注释2
pkg.codePath = apkFile.getAbsolutePath();
return pkg;
} finally {
IoUtils.closeQuietly(assets);
}
}
从parseClusterPackage的注释1和parseMonolithicPackage的注释2可以看出都是调用parseBaseApk去解析。
继续探究parseBaseApk方法：
private Package parseBaseApk(File apkFile, AssetManager assets, int flags)
throws PackageParserException {
...省略...
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);
parser = assets.openXmlResourceParser(cookie, ANDROID_MANIFEST_FILENAME);
final String[] outError = new String[1];
final Package pkg = parseBaseApk(res, parser, flags, outError);//注释1
if (pkg == null) {
throw new PackageParserException(mParseError,
apkPath + " (at " + parser.getPositionDescription() + "): " + outError[0]);
}
...省略...
} 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);
}
}
注释1处调用另一个重载的parseBaseApk方法对apk进行解析。
(4)根据（2）中注释4深入到PackageManagerService—>另一个scanPackageLI方法中
private PackageParser.Package scanPackageLI(PackageParser.Package pkg, int parseFlags,
int scanFlags, long currentTime, UserHandle user) throws PackageManagerException {
boolean success = false;
try {
final PackageParser.Package res = scanPackageDirtyLI(pkg, parseFlags, scanFlags,
currentTime, user);//注释1
success = true;
return res;
} finally {
if (!success && (scanFlags & SCAN_DELETE_DATA_ON_FAILURES) != 0) {
removeDataDirsLI(pkg.volumeUuid, pkg.packageName);
}
}
}
由注释1继续深入PackageManagerService—>scanPackageDirtyLI方法中：
private PackageParser.Package scanPackageDirtyLI(PackageParser.Package pkg, int parseFlags,
int scanFlags, long currentTime, UserHandle user) throws PackageManagerException {
final File scanFile = new File(pkg.codePath);
......省略......
// And now re-install the app.
ret = createDataDirsLI(pkg.volumeUuid, pkgName, pkg.applicationInfo.uid,
HasSystemUidErrors = true;//注释1
......省略......
//invoke installer to do the actual installation
int ret = createDataDirsLI(pkg.volumeUuid, pkgName, pkg.applicationInfo.uid,
pkg.applicationInfo.seinfo);//注释2
if (ret < 0) {
// Error from installer
throw new PackageManagerException(INSTALL_FAILED_INSUFFICIENT_STORAGE,
"Unable to create data dirs [errorCode=" + ret + "]");
}
......省略......
}
从注释1和注释2处看出调用了PMS中的createDataDirsLI方法，给installed发送消息，为应用程序创建对应的数据目录，如果目录已经存在，也会重新创建一遍。
深入到PMS的createDataDirsLI方法中：
private int createDataDirsLI(String volumeUuid, String packageName, int uid, String seinfo) {
int[] users = sUserManager.getUserIds();
int res = mInstaller.install(volumeUuid, packageName, uid, uid, seinfo);//注释1
if (res < 0) {
return res;
}
for (int user : users) {
if (user != 0) {
res = mInstaller.createUserData(volumeUuid, packageName,//注释2
UserHandle.getUid(user, uid), user, seinfo);
if (res < 0) {
return res;
}
}
}
return res;
}
从上面可知调用mInstaller.install()函数完成APK安装。
到此为止，系统应用的安装流程差不多就完成了。
6. 网络下载应用安装
网络应用下载完成后，会自动调用PackageManagerService中的installPackage方法：
@Override
public void installPackage(String originPath, IPackageInstallObserver2 observer,
int installFlags, String installerPackageName, VerificationParams verificationParams,
String packageAbiOverride) {
installPackageAsUser(originPath, observer, installFlags, installerPackageName,
verificationParams, packageAbiOverride, UserHandle.getCallingUserId());
}
可以看到主要是调用了PMS—>installPackageAsUser方法：
public void installPackageAsUser(String originPath, IPackageInstallObserver2 observer,
int installFlags, String installerPackageName, VerificationParams verificationParams,
String packageAbiOverride, int userId) {
mContext.enforceCallingOrSelfPermission(android.Manifest.permission.INSTALL_PACKAGES, null);
......省略......
final Message msg = mHandler.obtainMessage(INIT_COPY);
msg.obj = new InstallParams(origin, null, observer, params.installFlags,
installerPackageName, params.volumeUuid, verifParams, user, params.abiOverride,
params.grantedRuntimePermissions);
mHandler.sendMessage(msg);
}
主要是获取用户安装位置，将InstallParams对象封装在Message里，然后发一个Handler消息。
深入到处理INIT_COPY的地方：PMS—>doHandleMessage方法中：
void doHandleMessage(Message msg) {
switch (msg.what) {
case INIT_COPY: {
......省略......
if (!mBound) {
// If this is the only one pending we might
// have to bind to the service again.
if (!connectToService()) {
Slog.e(TAG, "Failed to bind to media container service");
params.serviceError();
return;
} else {
// Once we bind to the service, the first
// pending request will be processed.
mPendingInstalls.add(idx, params);
}
} else {
mPendingInstalls.add(idx, params);
// Already bound to the service. Just make
// sure we trigger off processing the first request.
if (idx == 0) {
mHandler.sendEmptyMessage(MCS_BOUND);
}
}
break;
}
case MCS_BOUND: {
if (DEBUG_INSTALL) Slog.i(TAG, "mcs_bound");
if (msg.obj != null) {
mContainerService = (IMediaContainerService) msg.obj;
}
if (mContainerService == null) {
......省略......
} else if (mPendingInstalls.size() > 0) {
HandlerParams params = mPendingInstalls.get(0);
if (params != null) {
if (params.startCopy()) {//注释1
// We are done... look for more work or to
// go idle.
if (DEBUG_SD_INSTALL) Log.i(TAG,
"Checking for more work or unbind...");
// Delete pending install
if (mPendingInstalls.size() > 0) {
mPendingInstalls.remove(0);
}
if (mPendingInstalls.size() == 0) {
if (mBound) {
if (DEBUG_SD_INSTALL) Log.i(TAG,
"Posting delayed MCS_UNBIND");
removeMessages(MCS_UNBIND);
Message ubmsg = obtainMessage(MCS_UNBIND);
// Unbind after a little delay, to avoid
// continual thrashing.
sendMessageDelayed(ubmsg, 10000);
}
} else {
// There are more pending requests in queue.
// Just post MCS_BOUND message to trigger processing
// of next pending install.
if (DEBUG_SD_INSTALL) Log.i(TAG,
"Posting MCS_BOUND for next work");
mHandler.sendEmptyMessage(MCS_BOUND);
}
}
}
} else {
// Should never happen ideally.
Slog.w(TAG, "Empty queue");
}
break;
}
如果msg.what是INIT_COPY：
则连接DefaultContainerService服务，将我们要安装的信息方法HandlerParams的mPendingInstalls中，然后再发送MCS_BOUND消息。
如果msg.what是MCS_BOUND:
则通过HandlerParams params = mPendingInstalls.get(0)获取要安装包的信息，然后清除包信息，如果还有其他包，则继续发MCS_BOUND消息，一直循环，直到安装包都安装完。
然后再调用PackageManagerService.HandlerParams—>startCopy方法：
final boolean startCopy() {
boolean res;
try {
if (DEBUG_INSTALL) Slog.i(TAG, "startCopy " + mUser + ": " + this);
if (++mRetries > MAX_RETRIES) {
Slog.w(TAG, "Failed to invoke remote methods on default container service. Giving up");
mHandler.sendEmptyMessage(MCS_GIVE_UP);
handleServiceError();
return false;
} else {
handleStartCopy();//注释1
res = true;
}
} catch (RemoteException e) {
if (DEBUG_INSTALL) Slog.i(TAG, "Posting install MCS_RECONNECT");
mHandler.sendEmptyMessage(MCS_RECONNECT);
res = false;
}
handleReturnCode();//注释2
return res;
}
其中startCopy中有两个重要的方法handleStartCopy和handleReturnCode。
handleStartCopy中会检查应用是否能安装成功，如果不能安装成功，则会返回failed的CODE；返回res标识，判断是否安装成功。
handleReturnCode方法有两处重载了，一个是删除时调用的，一个是安装时调用的，下面列出安装的地方：
@Override
void handleReturnCode() {
// If mArgs is null, then MCS couldn't be reached. When it
// reconnects, it will try again to install. At that point, this
// will succeed.
if (mArgs != null) {
processPendingInstall(mArgs, mRet);
}
}
可以看到调用了processPendingInstall方法：
private void processPendingInstall(final InstallArgs args, final int currentStatus) {
// Queue up an async operation since the package installation may take a little while.
mHandler.post(new Runnable() {
public void run() {
mHandler.removeCallbacks(this);
// Result object to be returned
PackageInstalledInfo res = new PackageInstalledInfo();
res.returnCode = currentStatus;
res.uid = -1;
res.pkg = null;
res.removedInfo = new PackageRemovedInfo();
if (res.returnCode == PackageManager.INSTALL_SUCCEEDED) {
args.doPreInstall(res.returnCode);
synchronized (mInstallLock) {
installPackageLI(args, res);//注释1
}
args.doPostInstall(res.returnCode, res.uid);
}
......省略......
}
从注释1处可以看到，调用的是installPackageLI方法：
private void installPackageLI(InstallArgs args, PackageInstalledInfo res) {
......省略......
if (replace) {
replacePackageLI(pkg, parseFlags, scanFlags | SCAN_REPLACING, args.user,
installerPackageName, volumeUuid, res);
} else {
installNewPackageLI(pkg, parseFlags, scanFlags | SCAN_DELETE_DATA_ON_FAILURES,
args.user, installerPackageName, volumeUuid, res);
}
......省略......
}
如果是替换安装，则走replacePackageLI的逻辑。追踪replacePackageLI的逻辑流程：
replacePackageLI—>如果是系统应用则调用replaceSystemPackageLI—>再调用PackageParser.Package的scanPackageLI方法。
replacePackageLI—>如果是非系统应用则调用replaceNonSystemPackageLI—>再调用PackageParser.Package的scanPackageLI方法。
如果是第一次安装，则走installNewPackageLI。追踪installNewPackageLI的逻辑流程：
installNewPackageLI—>再调用PackageParser.Package的scanPackageLI方法。
到了调用PackageParser.Package的scanPackageLI方法就到了系统应用安装过程中的“继续探究扫描安装过程”逻辑，后面的安装逻辑就与系统应用安装的逻辑一样了。
7. 通过命令安装应用
命令安装应用的入口是：
framework/base/cmds/pm/src/com/android/commands/pm/Pm.java
1
应用安装的时候就会调用runInstall()方法：
private int runInstall() {
......省略......
try {
VerificationParams verificationParams = new VerificationParams(verificationURI,
originatingURI, referrerURI, VerificationParams.NO_UID, null);
mPm.installPackageAsUser(apkFilePath, obs.getBinder(), installFlags,
installerPackageName, verificationParams, abi, userId);//注释1
......省略......
} catch (RemoteException e) {
System.err.println(e.toString());
System.err.println(PM_NOT_RUNNING_ERR);
return 1;
}
}
从注释1处可以看到安装逻辑调用的是PackageManagerService—>installPackageAsUser方法。后面的调用逻辑就与“网络下载应用安装”的逻辑一样了。
8. 通过外部设备安装应用
通过外部设备安装应用，调用的是Android内部的PackageInstaller去完成的，其本身也是一个apk。代码位置在
/packages/apps/PackageInstaller/
1
用于显示安装apk，但其最终的本质还是调用PackageManagerService去完成安装的。
当点击文件管理器中的apk时，文件管理器就会启动PackageInstaller中的PackageInstallerActivity,并将apk的信息通过intent传递给PackageInstallerActivity。
（1）深入到PackageInstallerActivity—>onCreate方法：
@Override
protected void onCreate(Bundle icicle) {
super.onCreate(icicle);
mPm = getPackageManager();
mInstaller = mPm.getPackageInstaller();//注释1
mUserManager = (UserManager) getSystemService(Context.USER_SERVICE);
final Intent intent = getIntent();
//注释2
if (PackageInstaller.ACTION_CONFIRM_PERMISSIONS.equals(intent.getAction())) {
final int sessionId = intent.getIntExtra(PackageInstaller.EXTRA_SESSION_ID, -1);
final PackageInstaller.SessionInfo info = mInstaller.getSessionInfo(sessionId);
if (info == null || !info.sealed || info.resolvedBaseCodePath == null) {
Log.w(TAG, "Session " + mSessionId + " in funky state; ignoring");
finish();
return;
}
mSessionId = sessionId;
mPackageURI = Uri.fromFile(new File(info.resolvedBaseCodePath));
mOriginatingURI = null;
mReferrerURI = null;
} else {
mSessionId = -1;
mPackageURI = intent.getData();
mOriginatingURI = intent.getParcelableExtra(Intent.EXTRA_ORIGINATING_URI);
mReferrerURI = intent.getParcelableExtra(Intent.EXTRA_REFERRER);
}
final boolean unknownSourcesAllowedByAdmin = isUnknownSourcesAllowedByAdmin();
final boolean unknownSourcesAllowedByUser = isUnknownSourcesEnabled();
//注释3
boolean requestFromUnknownSource = isInstallRequestFromUnknownSource(intent);
......省略.....
// Block the install attempt on the Unknown Sources setting if necessary.
if (!requestFromUnknownSource) {
initiateInstall();//注释4
return;
}
......省略.....
if (!unknownSourcesAllowedByAdmin
|| (!unknownSourcesAllowedByUser && isManagedProfile)) {
showDialogInner(DLG_ADMIN_RESTRICTS_UNKNOWN_SOURCES);
mInstallFlowAnalytics.setFlowFinished(
InstallFlowAnalytics.RESULT_BLOCKED_BY_UNKNOWN_SOURCES_SETTING);
} else if (!unknownSourcesAllowedByUser) {
// Ask user to enable setting first
showDialogInner(DLG_UNKNOWN_SOURCES);
mInstallFlowAnalytics.setFlowFinished(
InstallFlowAnalytics.RESULT_BLOCKED_BY_UNKNOWN_SOURCES_SETTING);
} else {
initiateInstall();//注释5
}
}
注释1：获取PackageInstaller对象
注释2：PackageInstaller检查权限
注释3：PackageInstaller检查是否开启未知来源
注释4、注释5：调用initiateInstall方法
（2）深入到PackageInstallerActivity—>initiateInstall方法
private void initiateInstall() {
String pkgName = mPkgInfo.packageName;
// Check if there is already a package on the device with this name
// but it has been renamed to something else.
String[] oldName = mPm.canonicalToCurrentPackageNames(new String[] { pkgName });
if (oldName != null && oldName.length > 0 && oldName[0] != null) {
pkgName = oldName[0];
mPkgInfo.packageName = pkgName;
mPkgInfo.applicationInfo.packageName = pkgName;
}
// Check if package is already installed. display confirmation dialog if replacing pkg
try {
// This is a little convoluted because we want to get all uninstalled
// apps, but this may include apps with just data, and if it is just
// data we still want to count it as "installed".
mAppInfo = mPm.getApplicationInfo(pkgName,
PackageManager.GET_UNINSTALLED_PACKAGES);
if ((mAppInfo.flags&ApplicationInfo.FLAG_INSTALLED) == 0) {
mAppInfo = null;
}
} catch (NameNotFoundException e) {
mAppInfo = null;
}
mInstallFlowAnalytics.setReplace(mAppInfo != null);
mInstallFlowAnalytics.setSystemApp(
(mAppInfo != null) && ((mAppInfo.flags & ApplicationInfo.FLAG_SYSTEM) != 0));
startInstallConfirm();//调用
}
initiateInstall方法主要负责检查是否已经安装过，是否是系统应用等。然后继续调用了startInstallConfirm方法。
(3) 深入到PackageInstallerActivity—>startInstallConfirm方法
private void startInstallConfirm() {
TabHost tabHost = (TabHost)findViewById(android.R.id.tabhost);
tabHost.setup();
ViewPager viewPager = (ViewPager)findViewById(R.id.pager);
TabsAdapter adapter = new TabsAdapter(this, tabHost, viewPager);
adapter.setOnTabChangedListener(new TabHost.OnTabChangeListener() {
@Override
public void onTabChanged(String tabId) {
if (TAB_ID_ALL.equals(tabId)) {
mInstallFlowAnalytics.setAllPermissionsDisplayed(true);
} else if (TAB_ID_NEW.equals(tabId)) {
mInstallFlowAnalytics.setNewPermissionsDisplayed(true);
}
}
});
// If the app supports runtime permissions the new permissions will
// be requested at runtime, hence we do not show them at install.
boolean supportsRuntimePermissions = mPkgInfo.applicationInfo.targetSdkVersion
>= Build.VERSION_CODES.M;
boolean permVisible = false;
mScrollView = null;
mOkCanInstall = false;
int msg = 0;
AppSecurityPermissions perms = new AppSecurityPermissions(this, mPkgInfo);
final int N = perms.getPermissionCount(AppSecurityPermissions.WHICH_ALL);
if (mAppInfo != null) {
msg = (mAppInfo.flags & ApplicationInfo.FLAG_SYSTEM) != 0
? R.string.install_confirm_question_update_system
: R.string.install_confirm_question_update;
mScrollView = new CaffeinatedScrollView(this);
mScrollView.setFillViewport(true);
boolean newPermissionsFound = false;
if (!supportsRuntimePermissions) {
newPermissionsFound =
(perms.getPermissionCount(AppSecurityPermissions.WHICH_NEW) > 0);
mInstallFlowAnalytics.setNewPermissionsFound(newPermissionsFound);
if (newPermissionsFound) {
permVisible = true;
mScrollView.addView(perms.getPermissionsView(
AppSecurityPermissions.WHICH_NEW));
}
}
if (!supportsRuntimePermissions && !newPermissionsFound) {
LayoutInflater inflater = (LayoutInflater)getSystemService(
Context.LAYOUT_INFLATER_SERVICE);
TextView label = (TextView)inflater.inflate(R.layout.label, null);
label.setText(R.string.no_new_perms);
mScrollView.addView(label);
}
adapter.addTab(tabHost.newTabSpec(TAB_ID_NEW).setIndicator(
getText(R.string.newPerms)), mScrollView);
} else {
findViewById(R.id.tabscontainer).setVisibility(View.GONE);
findViewById(R.id.divider).setVisibility(View.VISIBLE);
}
if (!supportsRuntimePermissions && N > 0) {
permVisible = true;
LayoutInflater inflater = (LayoutInflater)getSystemService(
Context.LAYOUT_INFLATER_SERVICE);
View root = inflater.inflate(R.layout.permissions_list, null);
if (mScrollView == null) {
mScrollView = (CaffeinatedScrollView)root.findViewById(R.id.scrollview);
}
((ViewGroup)root.findViewById(R.id.permission_list)).addView(
perms.getPermissionsView(AppSecurityPermissions.WHICH_ALL));
adapter.addTab(tabHost.newTabSpec(TAB_ID_ALL).setIndicator(
getText(R.string.allPerms)), root);
}
mInstallFlowAnalytics.setPermissionsDisplayed(permVisible);
if (!permVisible) {
if (mAppInfo != null) {
// This is an update to an application, but there are no
// permissions at all.
msg = (mAppInfo.flags & ApplicationInfo.FLAG_SYSTEM) != 0
? R.string.install_confirm_question_update_system_no_perms
: R.string.install_confirm_question_update_no_perms;
} else {
// This is a new application with no permissions.
msg = R.string.install_confirm_question_no_perms;
}
tabHost.setVisibility(View.GONE);
mInstallFlowAnalytics.setAllPermissionsDisplayed(false);
mInstallFlowAnalytics.setNewPermissionsDisplayed(false);
findViewById(R.id.filler).setVisibility(View.VISIBLE);
findViewById(R.id.divider).setVisibility(View.GONE);
mScrollView = null;
}
if (msg != 0) {
((TextView)findViewById(R.id.install_confirm_question)).setText(msg);
}
mInstallConfirm.setVisibility(View.VISIBLE);
mOk = (Button)findViewById(R.id.ok_button);
mOk.requestFocus();
mCancel = (Button)findViewById(R.id.cancel_button);
mOk.setOnClickListener(this);
mCancel.setOnClickListener(this);
//add by wangqi begin{@
TabWidget tabWidget = tabHost.getTabWidget();
int childCount = tabWidget.getChildCount();
if (childCount == 2) {
final View left = tabWidget.getChildAt(0);
final View right = tabWidget.getChildAt(1);
left.setId(tabWidget.getId() + 1);
right.setId(tabWidget.getId() + 2);
right.setNextFocusLeftId(left.getId());
right.setOnKeyListener(new View.OnKeyListener() {
@Override
public boolean onKey(View v, int keyCode, KeyEvent event) {
if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT && event.getAction() == KeyEvent.ACTION_DOWN) {
left.requestFocus();
}
return true;
}
});
}
// end @}
if (mScrollView == null) {
// There is nothing to scroll view, so the ok button is immediately
// set to install.
//mOk.setText(R.string.install);
mOkCanInstall = true;
} else {
mScrollView.setFullScrollAction(new Runnable() {
@Override
public void run() {
//mOk.setText(R.string.install);
mOkCanInstall = true;
}
});
}
}
startInstallConfirm主要负责界面初始化，显示权限信息等。
界面初始化完成后，安装界面就会呈现在用户面前，如果用户想要安装这个应用程序，可以直接点击确认按钮，此时就会调用PackageInstallerActivity中的onClick方法：
public void onClick(View v) {
if (v == mOk) {
if (mOkCanInstall || mScrollView == null) {
mInstallFlowAnalytics.setInstallButtonClicked();
if (mSessionId != -1) {
mInstaller.setPermissionsResult(mSessionId, true);
// We're only confirming permissions, so we don't really know how the
// story ends; assume success.
mInstallFlowAnalytics.setFlowFinishedWithPackageManagerResult(
PackageManager.INSTALL_SUCCEEDED);
finish();
} else {
startInstall();//注释1
}
} else {
mScrollView.pageScroll(View.FOCUS_DOWN);
}
} else if(v == mCancel) {
// Cancel and finish
setResult(RESULT_CANCELED);
if (mSessionId != -1) {
mInstaller.setPermissionsResult(mSessionId, false);
}
mInstallFlowAnalytics.setFlowFinished(
InstallFlowAnalytics.RESULT_CANCELLED_BY_USER);
finish();
}
}
onClick方法中分别会对取消和确定按钮做处理，如果是确定按钮，就会调用注释1处的startInstall方法。
(4) 深入到PackageInstallerActivity—>startInstall方法
private void startInstall() {
// Start subactivity to actually install the application
Intent newIntent = new Intent();
newIntent.putExtra(PackageUtil.INTENT_ATTR_APPLICATION_INFO,
mPkgInfo.applicationInfo);
newIntent.setData(mPackageURI);
newIntent.setClass(this, InstallAppProgress.class);//跳转的Activity
newIntent.putExtra(InstallAppProgress.EXTRA_MANIFEST_DIGEST, mPkgDigest);
newIntent.putExtra(
InstallAppProgress.EXTRA_INSTALL_FLOW_ANALYTICS, mInstallFlowAnalytics);
String installerPackageName = getIntent().getStringExtra(
Intent.EXTRA_INSTALLER_PACKAGE_NAME);
......省略.....
if(localLOGV) Log.i(TAG, "downloaded app uri="+mPackageURI);
startActivity(newIntent);//注释1
finish();
}
startInstall方法启动后，将会跳转到注释1处的InstallAppProgress界面。并关掉当前的PackageInstallerActivity
(5) 深入到InstallAppProgress.java文件中
当InstallAppProgress.java启动时，会先调用InstallAppProgress.java—>onCreate方法：
@Override
public void onCreate(Bundle icicle) {
......省略.....
initView();
}
onCreate方法中会调用initView方法初始化界面：
public void initView() {
......省略.....
if ("package".equals(mPackageURI.getScheme())) {
try {
pm.installExistingPackage(mAppInfo.packageName);
observer.packageInstalled(mAppInfo.packageName,
PackageManager.INSTALL_SUCCEEDED);
} catch (PackageManager.NameNotFoundException e) {
observer.packageInstalled(mAppInfo.packageName,
PackageManager.INSTALL_FAILED_INVALID_APK);
}
} else {
pm.installPackageWithVerificationAndEncryption(mPackageURI, observer, installFlags,
installerPackageName, verificationParams, null);
}
}
可以看到有两条安装逻辑，我这里只探索else中的逻辑。else中实际上是调用了ApplicationPackageManager的installPackageWithVerificationAndEncryption方法来安装。
(6) 深入到ApplicationPackageManager—>installPackageWithVerificationAndEncryption方法：
@Override
public void installPackageWithVerificationAndEncryption(Uri packageURI,
PackageInstallObserver observer, int flags, String installerPackageName,
VerificationParams verificationParams, ContainerEncryptionParams encryptionParams) {
installCommon(packageURI, observer, flags, installerPackageName, verificationParams,
encryptionParams);//注释1
}
注意installPackageWithVerificationAndEncryption方法上有个Override，说明继承于父类的PackageManager中。
从注释1中可以看到调用的是installCommon方法：
private void installCommon(Uri packageURI,
PackageInstallObserver observer, int flags, String installerPackageName,
VerificationParams verificationParams, ContainerEncryptionParams encryptionParams) {
......省略.....
try {
mPM.installPackage(originPath, observer.getBinder(), flags, installerPackageName,
verificationParams, null);//注释1
} catch (RemoteException ignored) {
}
}
从注释1中可以看到调用的是PMS中的installPackage方法。到这里后续的逻辑就与前面的“网络下载应用安装”中的逻辑一样了。