概述
一讲到APK安装流程，它有四种安装方式：
- 系统应用和预制应用安装，开机时完成，没有安装界面，在PKMS的构造函数中欧冠完成安装
- 网络下载应用安装，通过应用商店来完成，调用PackageManager.installPackages()，有安装界面
- ADB工具安装，没有安装界面，它通过启动pm脚本的形式，然后调用com.android.commands.pm.Pm类，之后调用到PMS.installStage()完成安装
- 第三方应用安装，通过SD卡里的APK文件安装，有安装界面，由packageinstaller.apk应用处理安装及卸载过程的界面.
均是通过PackageInstallObserver来监听安装是否成功。
应用安装涉及到如下几个目录：
system/app ---------------系统自带的应用程序，获得adb root权限才能删除
data/app ---------------用户程序安装的目录。用户 安装时把apk文件 复制 到此目录 data/data ---------------存放应用程序的数据 data/dalvik-cache--------将apk中的dex文件安装到dalvik-cache目录下(dex文件是dalvik虚拟机的可执行文件, 其大小约为原始apk文件大小的四分之一)
安装过程：
复制APK安装包到data/app目录下，解压并扫描安装包，把dex文件(Dalvik字节码)保存到dalvik-cache目录，并data/data目录下创建对应的应用数据目录。
卸载过程：
删除 安装过程中在上述三个目录下创建的文件及目录。
安装应用的过程解析
一.开机安装 PackageManagerService处理各种 应用的安装，卸载，管理等工作，开机时 由systemServer启动此服务
(源文件路径：android\frameworks\base\services\java\com\android\server\PackageManagerService.java)
PackageManagerService服务 启动的流程：
1 .首先 扫描安装 “system\framework” 目录下的jar包
// 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);
2.扫描 安装系统system/app的应用程序
// 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);
3.制造商的目录下/vendor/app应用包
// 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);
4.扫描 “data\app”目录，即用户安装的第三方应用
**scanDirLI**(mAppInstallDir, 0, scanMode, 0);
5.扫描" data\app-private"目录，即安装DRM保护的APK文件（一个受保护的歌曲或受保 护的视频是使用 DRM 保护的文件）
scanDirLI(mDrmAppPrivateInstallDir, PackageParser.PARSE_FORWARD_LOCK,
• scanMode, 0);
扫描方法的代码清单
private void scanDirLI(File dir, int flags, int scanMode, long currentTime) {
• String[] files = dir.list();
• if (files == null) {
• Log.d(TAG, "No files in app dir " + dir);
• return;
• }
• if (false) {
• Log.d(TAG, "Scanning app dir " + dir);
• }
• 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();
• }
• }
}
并且从该扫描方法中可以看出调用了scanPackageLI（）
private PackageParser.Package scanPackageLI(File scanFile,
int parseFlags, int scanMode, long currentTime)
跟踪scanPackageLI（）方法后发现，程序经过很多次的if else 的筛选，最后判定 可以安装apk后，调用了 mInstaller.install
if (mInstaller != null) {
• int ret = **mInstaller****.install**(pkgName, useEncryptedFSDir, pkg.applicationInfo.uid,pkg.applicationInfo.uid);
• if(ret < 0) {
• // Error from installer
• mLastScanError = PackageManager.INSTALL_FAILED_INSUFFICIENT_STORAGE;
• return null;
• }
• }
mInstaller.install（） 通过
LocalSocketAddress address = new LocalSocketAddress(
• "**installd**", LocalSocketAddress.Namespace.RESERVED);
指挥installd在C语言的文件中完成工作
PackageManagerService小节 ：
1)从apk, xml中载入pacakge信息, 存储到内部成员变量中, 用于后面的查找. 关键的方法是scanPackageLI(). 2)各种查询操作, 包括query Intent操作. 3)install package和delete package的操作. 还有后面的关键方法是installPackageLI().
二、从网络上下载应用：
下载完成后，会自动调用Packagemanager的安装方法installPackage（）
/* Called when a downloaded package installation has been confirmed by the user */
由英文注释可见PackageManagerService 类的installPackage（）函数为 安装程序 的入口。
public void installPackage(
• final Uri packageURI, final IPackageInstallObserver observer, final int flags,
• final String installerPackageName) {
• mContext.enforceCallingOrSelfPermission(
• android.Manifest.permission.INSTALL_PACKAGES, null);
• Message msg = mHandler.obtainMessage(INIT_COPY);
• msg.obj = new InstallParams(packageURI, observer, flags,
• installerPackageName);
• **mHandler****.sendMessage**(msg);
}
其中是通过PackageHandler的实例mhandler.sendMessage（msg）把信息发给继承Handler的类HandleMessage()方法
class PackageHandler extends Handler{
•
*****************省略若干********************
• public void handleMessage(Message msg) {
• try {
• doHandleMessage(msg);
• } finally {
• Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND);
• }
• }
******************省略若干**********************
}
把信息发给doHandleMessage()方法,方法中用switch（）语句进行判定传来Message
void doHandleMessage(Message msg) {
• switch (msg.what) {
•
• case INIT_COPY: {
• if (DEBUG_SD_INSTALL) Log.i(TAG, "init_copy");
• HandlerParams params = (HandlerParams) msg.obj;
• int idx = mPendingInstalls.size();
• if (DEBUG_SD_INSTALL) Log.i(TAG, "idx=" + idx);
• // If a bind was already initiated we dont really
• // need to do anything. The pending install
• // will be processed later on.
• 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_SD_INSTALL) Log.i(TAG, "mcs_bound");
• if (msg.obj != null) {
• mContainerService = (IMediaContainerService) msg.obj;
• }
• if (mContainerService == null) {
• // Something seriously wrong. Bail out
• Slog.e(TAG, "Cannot bind to media container service");
• for (HandlerParams params : mPendingInstalls) {
• mPendingInstalls.remove(0);
• // Indicate service bind error
• params.serviceError();
• }
• mPendingInstalls.clear();
• } else if (mPendingInstalls.size() > 0) {
• HandlerParams params = mPendingInstalls.get(0);
• if (params != null) {
• params.startCopy();
• }
• } else {
• // Should never happen ideally.
• Slog.w(TAG, "Empty queue");
• }
• break;
• }
• ****************省略若干**********************
}
}
public final boolean sendMessage ([Message](http://developer.android.com/reference/android/os/Message.html) msg)
public final boolean sendEmptyMessage (int what)
两者参数有别。
然后调用抽象类HandlerParams中的一个startCopy（）方法
abstract class HandlerParams {
final void startCopy() {
***************若干if语句判定否这打回handler消息*******
handleReturnCode();
}
}
handleReturnCode（）复写了两次其中有一次是删除时要调用的，只列出安装调用的一个方法
@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);
• }
• }
这时可以清楚的看见 processPendingInstall（）被调用。
其中run（）方法如下
run(){
synchronized (mInstallLock) {
• ************省略*****************
• installPackageLI(args, true, res);
•
}
}
instaPacakgeLI（）args,res参数分析
//InstallArgs 是在PackageService定义的static abstract class InstallArgs 静态抽象类。
static abstract class InstallArgs {
其中定义了flag标志，packageURL，创建文件，拷贝apk，修改包名称，
还有一些删除文件的清理，释放存储函数。
}
class PackageInstalledInfo {
• String name;
• int uid;
• PackageParser.Package pkg;
• int returnCode;
• PackageRemovedInfo removedInfo;
}
private void installPackageLI(InstallArgs args,
boolean newInstall,
PackageInstalledInfo res) { int pFlags = args.flags; String installerPackageName = args.installerPackageName;
File tmpPackageFile = new File(args.getCodePath());
boolean forwardLocked = ((pFlags & PackageManager.INSTALL_FORWARD_LOCK) != 0);
boolean onSd = ((pFlags & PackageManager.INSTALL_EXTERNAL) != 0);
boolean replace = false;
int scanMode = (onSd ? 0 : SCAN_MONITOR)
| SCAN_FORCE_DEX
| SCAN_UPDATE_SIGNATURE
| (newInstall ? SCAN_NEW_INSTALL : 0);
// Result object to be returned res.returnCode = PackageManager.INSTALL_SUCCEEDED;
// Retrieve PackageSettings and parse package int parseFlags = PackageParser.PARSE_CHATTY
| (forwardLocked ? PackageParser.PARSE_FORWARD_LOCK :
0) | (onSd ? PackageParser.PARSE_ON_SDCARD : 0);
parseFlags |= mDefParseFlags;
PackageParser pp = new PackageParser(tmpPackageFile.getPath());
pp.setSeparateProcesses(mSeparateProcesses);
final PackageParser.Package pkg = pp.parsePackage(tmpPackageFile, null, mMetrics, parseFlags);
if (pkg == null) { res.returnCode = pp.getParseError();
return;
} String pkgName = res.name = pkg.packageName;
if ((pkg.applicationInfo.flags&ApplicationInfo.FLAG_TEST_ONLY) != 0)
{
if ((pFlags&PackageManager.INSTALL_ALLOW_TEST) == 0) { res.returnCode = PackageManager.INSTALL_FAILED_TEST_ONLY;
return;
}
}
if (GET_CERTIFICATES && !pp.collectCertificates(pkg, parseFlags))
{ res.returnCode = pp.getParseError();
return;
} // Get rid of all references to package scan path via parser. pp = null;
String oldCodePath = null;
boolean systemApp = false;
synchronized (mPackages)
{
// Check if installing already existing package if ((pFlags&PackageManager.INSTALL_REPLACE_EXISTING) != 0) { String oldName = mSettings.mRenamedPackages.get(pkgName);
if (pkg.mOriginalPackages != null && pkg.mOriginalPackages.contains(oldName) && mPackages.containsKey(oldName)) {
// This package is derived from an original package, // and this device has been updating from that original
// name. We must continue using the original name, so
// rename the new package here. pkg.setPackageName(oldName);
pkgName = pkg.packageName; replace = true;
}
else if (mPackages.containsKey(pkgName))
{
// This package, under its official name, already exists
// on the device; we should replace it. replace = true;
}
}
PackageSetting ps = mSettings.mPackages.get(pkgName);
if (ps != null) { oldCodePath = mSettings.mPackages.get(pkgName).codePathString;
if (ps.pkg != null && ps.pkg.applicationInfo != null)
{
systemApp = (ps.pkg.applicationInfo.flags & ApplicationInfo.FLAG_SYSTEM) != 0;
}
}
}
if (systemApp && onSd)
{
// Disable updates to system apps on sdcard Slog.w(TAG, "Cannot install updates to system apps on sdcard");
res.returnCode = PackageManager.INSTALL_FAILED_INVALID_INSTALL_LOCATION; return;
}
if
(!args.doRename(res.returnCode, pkgName, oldCodePath))
{
res.returnCode = PackageManager.INSTALL_FAILED_INSUFFICIENT_STORAGE;
return;
}
// Set application objects path explicitly after the rename setApplicationInfoPaths(pkg, args.getCodePath(), args.getResourcePath()); pkg.applicationInfo.nativeLibraryDir = args.getNativeLibraryPath();
if (replace) { replacePackageLI(pkg, parseFlags, scanMode, installerPackageName, res);
}
else
{
installNewPackageLI(pkg, parseFlags, scanMode, installerPackageName,res);
}
}
最后判断 如果以前 不存在 那么调用installNewPackageLI(）
private void installNewPackageLI
(PackageParser.Package pkg, int parseFlags,
int scanMode,
String installerPackageName,
PackageInstalledInfo res)
{ **********省略若干************** PackageParser.Package newPackage = **scanPackageLI**(pkg, parseFlags, scanMode,
System.currentTimeMillis());
*******省略若干*****}
最后终于 回到了和 开机安装 一样的地方. 与开机方式安装 调用统一方法。
三、从ADB工具安装
其 入口函数 源文件为pm.java
(源文件路径：android\frameworks\base\cmds\pm\src\com\android\commands\pm\Pm.java)
其中\system\framework\pm.jar 包管理库
包管理脚本 \system\bin\pm 解析
*Pm.java *文件里的 showUsage就是使用方法
private static void showUsage()
{
System.err.println("usage: pm [list|path|install|uninstall]");
System.err.println(" pm list packages [-f]");
System.err.println(" pm list permission-groups");
System.err.println(" pm list permissions [-g] [-f] [-d] [-u] [GROUP]");
System.err.println(" pm list instrumentation [-f] [TARGET-PACKAGE]");
System.err.println(" pm list features"); System.err.println(" pm path PACKAGE");
System.err.println(" pm install [-l] [-r] [-t] [-i INSTALLER_PACKAGE_NAME] [-s] [-f] PATH");
System.err.println(" pm uninstall [-k] PACKAGE"); System.err.println(" pm enable PACKAGE_OR_COMPONENT");
System.err.println(" pm disable PACKAGE_OR_COMPONENT");
System.err.println(" pm setInstallLocation [0/auto] [1/internal] [2/external]");
**************省略**************
}
安装时候 会调用 runInstall（）方法
private void runInstall()
{
int installFlags = 0;
String installerPackageName = null;
String opt;
while ((opt=nextOption()) != null)
{
if (opt.equals("-l"))
{
installFlags |= PackageManager.INSTALL_FORWARD_LOCK; }
else if (opt.equals("-r")) { installFlags |= PackageManager.INSTALL_REPLACE_EXISTING;
}
else if (opt.equals("-i")) { installerPackageName = nextOptionData();
if (installerPackageName == null) { System.err.println("Error: no value specified for -i");
showUsage();
return;
}
}
else if (opt.equals("-t"))
{
installFlags |= PackageManager.INSTALL_ALLOW_TEST;
}
else if (opt.equals("-s"))
{ // Override if -s option is specified. installFlags |= PackageManager.INSTALL_EXTERNAL;
}
else if (opt.equals("-f"))
{
// Override if -s option is specified. installFlags |= PackageManager.INSTALL_INTERNAL;
}
else { System.err.println("Error: Unknown option: " + opt);
showUsage();
return;
}
} String apkFilePath = nextArg(); System.err.println("\tpkg: " + apkFilePath);
if (apkFilePath == null) { System.err.println("Error: no package specified"); showUsage();
return;
}
**PackageInstallObserver** obs = new PackageInstallObserver();
try { mPm.installPackage(Uri.fromFile(new File(apkFilePath)), obs, installFlags, installerPackageName);
synchronized (obs) { while (!obs.finished) { try { obs.wait();
} catch (InterruptedException e) {
}
}
if (obs.result == PackageManager.INSTALL_SUCCEEDED) { System.out.println("Success");
} else { System.err.println("Failure [" + installFailureToString(obs.result) + "]");
}
}
} catch (RemoteException e) { System.err.println(e.toString()); System.err.println(PM_NOT_RUNNING_ERR);
}
}
其中
PackageInstallObserver obs = new PackageInstallObserver();
• mPm.installPackage(Uri.fromFile(new File(apkFilePath)), obs, installFlags,
• installerPackageName);
如果 安装成功
obs.result == PackageManager.INSTALL_SUCCEEDED)
又因为有
IPackageManage mPm；
mPm = IpackageManager.Stub.asInterface(ServiceManager.getService("package"));
Stub是接口IPackageManage的静态抽象类，asInterface是返回IPackageManager代理的静态方法。
因为class PackageManagerService extends IPackageManager.Stub
所以mPm.installPackage 调用
/* Called when a downloaded package installation has been confirmed by the user */
public void **installPackage**(
• final Uri packageURI, final IPackageInstallObserver observer, final int flags,final String installerPackageName)
这样 最后 就是 相当于 调用 从网络下载安装的 入口了。
四,从SD卡安装
系统调用 PackageInstallerActivity.java
源码路径：android/packages/ apps/PackageInstaller/src/com/android/packageinstaller/PackageInstallerActivity.java
进入这个Activity会判断信息是否有错，然后调用
private void initiateInstall() 判断 是否 曾经有过 同名包的安装，或者包已经安装
通过后 执行private void startInstallConfirm() 点击OK按钮后经过一系列的安装信息的判断 Intent跳转到
public class **InstallAppProgress**
extends Activity implements View.OnClickListener, OnCancelListener public void onCreate(Bundle icicle)
{
super.onCreate(icicle);
Intent intent = getIntent();
mAppInfo = intent.getParcelableExtra(PackageUtil.INTENT_ATTR_APPLICATION_INFO);
mPackageURI = intent.getData();
**initView**();
}
方法中调用了initView（）方法
public void initView() { requestWindowFeature(Window.FEATURE_NO_TITLE); setContentView(R.layout.op_progress);
int installFlags = 0;
PackageManager pm = getPackageManager();
try { PackageInfo pi = pm.getPackageInfo(mAppInfo.packageName, PackageManager.GET_UNINSTALLED_PACKAGES);
if(pi != null) { installFlags |= PackageManager.INSTALL_REPLACE_EXISTING;
}
}
catch (NameNotFoundException e) { }
if((installFlags & PackageManager.INSTALL_REPLACE_EXISTING )!= 0)
{ Log.w(TAG, "Replacing package:" + mAppInfo.packageName);
}
PackageUtil.AppSnippet as = PackageUtil.getAppSnippet(this, mAppInfo, mPackageURI);
mLabel = as.label; PackageUtil.initSnippetForNewApp(this, as, R.id.app_snippet);
mStatusTextView = (TextView)findViewById(R.id.center_text); mStatusTextView.setText(R.string.installing);
mProgressBar = (ProgressBar) findViewById(R.id.progress_bar); mProgressBar.setIndeterminate(true);
// Hide button till progress is being displayed mOkPanel = (View)findViewById(R.id.buttons_panel);
mDoneButton = (Button)findViewById(R.id.done_button); mLaunchButton = (Button)findViewById(R.id.launch_button);
mOkPanel.setVisibility(View.INVISIBLE);
String installerPackageName = getIntent().getStringExtra( Intent.EXTRA_INSTALLER_PACKAGE_NAME);
PackageInstallObserver observer = new PackageInstallObserver();
pm.**installPackage**(mPackageURI, observer, installFlags, installerPackageName);
}
以上就是Android中apk的安装流程详细解析；如需更多进阶Android技术交流可以前往下方链接： 传送直达↓↓↓ docs.qq.com/doc/DUkNRVF…
总结：
1.系统应用安装――开机时完成
2.网络下载应用安装――最后 会 调用 系统应用安装 的 scanPackageLI 接口；
3.ADB工具安装――最后 会 调用 网络下载应用安装 的installPackage 接口，从而 相当于 走的 还是系统应用安装 的 路径；
4.第三方应用安装――由 packageinstaller.apk 应用处理安装及卸载，最后也会 调用 网络下载应用安装 的installPackage 接口，从而 相当于 走的 还是系统应用安装 的 路径。
