Android(安卓)APK安装过程及原理详解

http://blog.csdn.net/hdhd588/article/details/6739281

应用程序包的安装是android的特点

APK---AndroidPackage

Android应用安装有如下四种方式：

1.系统应用安装---开机时完成，没有安装界面

2.网络下载应用安装---通过market应用完成，没有安装界面

3.ADB工具安装---没有安装界面。

4.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。

应用安装的流程及路径
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。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

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);       }   }

其中的

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)

这样就是从网络下载安装的入口了。

四,从SD卡安装

系统调用PackageInstallerActivity.java（/home/zhongda/androidSRC/vortex-8inch-for-hoperun/packages/apps/PackageInstaller/src/com/android/packageinstaller）

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);    }

方法最后我们可以看到再次调用安装接口installPackage()完成安装。

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