Android APK安装过程【手把手细节解析】_守住Android最后的光_apk安装流程

网络投稿 02-07 2558

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 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技术资料，可以点击查看《Android核心技术手册》获得免费方法。

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。