一、概述
APK为AndroidPackage的缩写,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。
应用安装涉及到如下几个目录:
(1)system/app:系统自带的应用程序,获得adb root权限才能删除
(2)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
(3)data/data:存放应用程序运行产生的数据
(4)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:
(1)复制APK安装包到data/app目录下,解压并扫描安装包,
(2)将dex文件(Dalvik字节码)保存到dalvik-cache目录,
(3)在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。
1、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
(1)首先扫描安装“system/framework”目录下的jar包
scanDirLI(mFrameworkDir, PackageParser.PARSE_IS_SYSTEM, scanMode | SCAN_NO_DEX);
(2)扫描安装“system/app”目录下的各个系统应用
scanDirLI(mSystemAppDir,PackageParser.PARSE_IS_SYSTEM, scanMode);
扫描“data/app”目录,即用户安装的第三方应用
scanDirLI(mAppInstallDir, 0, scanMode);
扫描" data/app-PRivate"目录,即安装DRM保护的APK文件(目前没有遇到过此类的应用)
scanDirLI(mDrmAppPrivateInstallDir,0, scanMode | SCAN_FORWARD_LOCKED)
(3)安装应用的过程
scanDirLI(Filedir, int flags, int scanMode) 遍历安装指定目录下的文件
scanPackageLI(FilescanFile,File destCodeFile, FiledestResourceFile, int parseFlags,int scanMode) 安装package文件
scanPackageLI(File scanFile, File destCodeFile, FiledestResourceFile,PackageParser.Package pkg, intparseFlags, int scanMode)通过解析安装包parsePackage获取到安装包的信息结构
mInstaller.install(pkgName,pkg.applicationInfo.uid,pkg.applicationInfo.uid); 实现文件复制的安装过程
2、从market上下载应用
Google Market应用需要使用Gmail账户登录才可以使用,选择某一应用后,开始下载安装包,此过程中,在手机的信号区有进度条提示,下载完成后,会自动调用PackageManager#installPackage接口
3、从ADB工具安装
Android Debug Bridge (adb) 是SDK自带的管理设备的工具,通过ADB命令行的方式也可以为手机或模拟器安装应用,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
ADB命令行的形式为adb install <path_to_apk> ,还可以带安装参数如:"-l""-r" "-i" "-t"
函数runInstall()中判断参数:"-l"――INSTALL_FORWARD_LOCK"-r"——INSTALL_REPLACE_EXISTING "-i" ——installerPackageName"-t"——INSTALL_ALLOW_TEST
我们常用的参数为-r,表示覆盖安装手机上已安装的同名应用。从market上下载的应用,也是直接传入这个参数安装的。
runInstall与market调用同样的接口完成应用安装。
public void installPackage(android.net.Uri packageURI,android.content.pm.ipackageInstallObserver observer, int flags,java.lang.String installerPackageName)
4、第三方应用安装――通过SD卡里的APK文件安装
把APK安装包保存在SD卡中,从手机里访问SD卡中的APK安装包,点击就可以启动安装界面,系统应用Packageinstaller.apk处理这种方式下的安装及卸载界面流程。
首先PackageInstallerActivity负责解析包,判断是否是可用的Apk文件,然后,创建临时安装文件/data/data/com.android.packageinstaller/files/ApiDemos.apk,并启动安装确认界面startInstallConfirm,列出解析得到的该应用基本信息。如果手机上已安装有同名应用,则需要用户确认是否要替换安装。确认安装后,启动InstallAppProgress,调用安装接口完成安装。
pm.installPackage(mPackageURI,observer, installFlags);
【PS】
(1)PackageManagerService.java的内部类AppDirObserver实现了监听app目录的功能:当把某个APK拖到app目录下时,可以直接调用scanPackageLI完成安装。
(2)手机数据区目录“data/system/packages.xml”文件中,包含了手机上所有已安装应用的基本信息,如安装路径,申请的permission等信息。
二、PMS#installPackage
installPackage方法中主要调用了installPackageAsUser,其源码如下:
public void installPackage(String originPath, IPackageInstallObserver2 observer, int installFlags, String installerPackageName, VerificationParams verificationParams, String packageAbiOverride) { installPackageAsUser(originPath, observer, installFlags, installerPackageName, verificationParams, packageAbiOverride, UserHandle.getCallingUserId()); } 再看installPackageAsUser,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); final int callingUid = Binder.getCallingUid(); enforceCrossUserPermission(callingUid, userId, true, true, "installPackageAsUser"); if (isUserRestricted(userId, UserManager.DISALLOW_INSTALL_APPS)) { try { if (observer != null) { observer.onPackageInstalled("", INSTALL_FAILED_USER_RESTRICTED, null, null); } } catch (RemoteException re) { } return; } if ((callingUid == Process.SHELL_UID) || (callingUid == Process.ROOT_UID)) { installFlags |= PackageManager.INSTALL_FROM_ADB; } else { // Caller holds INSTALL_PACKAGES permission, so we're less strict // about installerPackageName. installFlags &= ~PackageManager.INSTALL_FROM_ADB; installFlags &= ~PackageManager.INSTALL_ALL_USERS; } UserHandle user; if ((installFlags & PackageManager.INSTALL_ALL_USERS) != 0) { user = UserHandle.ALL; } else { user = new UserHandle(userId); } // Only system components can circumvent runtime permissions when installing. if ((installFlags & PackageManager.INSTALL_GRANT_RUNTIME_PERMISSIONS) != 0 && mContext.checkCallingOrSelfPermission(Manifest.permission .INSTALL_GRANT_RUNTIME_PERMISSIONS) == PackageManager.PERMISSION_DENIED) { throw new SecurityException("You need the " + "android.permission.INSTALL_GRANT_RUNTIME_PERMISSIONS permission " + "to use the PackageManager.INSTALL_GRANT_RUNTIME_PERMISSIONS flag"); } verificationParams.setInstallerUid(callingUid); final File originFile = new File(originPath); final OriginInfo origin = OriginInfo.fromUntrustedFile(originFile); // 直接交给mHandler来处理了,这个mHandler在PackageManagerService构造函数中初始化,是一个PackageHandler实例 final Message msg = mHandler.obtainMessage(INIT_COPY); msg.obj = new InstallParams(origin, null, observer, installFlags, installerPackageName, null, verificationParams, user, packageAbiOverride, null); mHandler.sendMessage(msg); } 再看PackageHandler类class PackageHandler extends Handler { PackageHandler(Looper looper) { super(looper); } public void handleMessage(Message msg) { try { doHandleMessage(msg); } finally { Process.setThreadPriority(Process.THREAD_PRIORITY_BACKGROUND); } } void doHandleMessage(Message msg) { switch (msg.what) { case INIT_COPY: { HandlerParams params = (HandlerParams) msg.obj; int idx = mPendingInstalls.size(); if (DEBUG_INSTALL) Slog.i(TAG, "init_copy idx=" + idx + ": " + params); // 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_INSTALL) Slog.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) { // Indicate service bind error params.serviceError(); } mPendingInstalls.clear(); } else if (mPendingInstalls.size() > 0) { HandlerParams params = mPendingInstalls.get(0);//获取第一个任务 if (params != null) { if (params.startCopy()) {//开始安装 // 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; } ... } }...} 首先,sendMessage发出的消息由PackageHandler.handleMessage()捕获,而具体的执行由PackageHandler.doHandleMessage()完成,接着,调用抽象类HandlerParams中的一个startCopy()方法,进而调用scanPackageLI()。
新闻热点
疑难解答