Android应用程序安装过程解析(源码解析)

￡神魔★判官ぃ 2022-07-14 15:56 274阅读 0赞

Android应用程序安装过程解析

# 1.程序安装的4大步骤 #

## （1） 拷贝apk文件到指定目录 ##

在Android系统中，apk安装文件是会被保存起来的，默认情况下，用户安装的apk首先会被拷贝到 /data/app 目录下。

/data/app目录是用户有权限访问的目录，在安装apk的时候会自动选择该目录存放用户安装的文件，而系统出厂的apk文件则被放到了 /system 分区下,包括 /system/app，/system/vendor/app，以及 /system/priv-app 等等，该分区只有Root权限的用户才能访问，这也就是为什么在没有Root手机之前，我们无法删除系统出厂的app的原因了。

## （2） 解压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，缓存起来。

然后，在/data/data/目录下创建应用程序的数据目录（以应用的包名命名），存放应用的相关数据，如数据库、xml文件、cache、二进制的so动态库等等。

## （3） 解析apk的AndroidManifinest.xml文件 ##

Android系统中，也有一个类似注册表的东西，用来记录当前所有安装的应用的基本信息，每次系统安装或者卸载了任何apk文件，都会更新这个文件。这个文件位于如下目录：

/data/system/packages.xml

系统在安装apk的过程中，会解析apk的AndroidManifinest.xml文件，提取出这个apk的重要信息写入到packages.xml文件中，这些信息包括：权限、应用包名、APK的安装位置、版本、userID等等。

由此，我们就知道了为啥一些应用市场和软件管理类的app能够很清楚地知道当前手机所安装的所有的app，以及这些app的详细信息了。

另外一件事就是Linux的用户Id和用户组Id，以便他可以获得合适的运行权限。

以上这些都是由PackageServiceManager完成的，下面我们会重点介绍PackageServiceManager。

## （4） 显示快捷方式 ##

这些应用程序只是相当于在PackageManagerService服务注册好了，如果我们想要在Android桌面上看到这些应用程序，还需要有一个Home应用程序，负责从PackageManagerService服务中把这些安装好的应用程序取出来，并以友好的方式在桌面上展现出来，例如以快捷图标的形式。在Android系统中，负责把系统中已经安装的应用程序在桌面中展现出来的Home应用程序就是Launcher了

# 2.PackageManagerService的启动过程 #

Android系统在启动的过程中，会启动一个应用程序管理服务PackageManagerService，这个服务负责扫描系统中特定的目录，找到里面的应用程序文件，即以Apk为后缀的文件，然后对这些文件进解析，得到应用程序的相关信息。

应用程序管理服务PackageManagerService安装应用程序的过程，其实就是解析析应用程序配置文件AndroidManifest.xml的过程，并从里面得到得到应用程序的相关信息，例如得到应用程序的组件Activity、Service、Broadcast Receiver和Content Provider等信息，有了这些信息后，通过ActivityManagerService这个服务，我们就可以在系统中正常地使用这些应用程序了。

应用程序管理服务PackageManagerService是系统启动的时候由SystemServer组件启动的，启后它就会执行应用程序安装的过程，因此，本文将从SystemServer启动PackageManagerService服务的过程开始分析系统中的应用程序安装的过程。

## 下面我们具体分析每一个步骤。 ##

##Step 1. SystemServer.main
    
        这个函数定义在frameworks/base/services/Java/com/android/server/SystemServer.java文件中：

[java] view plain copy public class SystemServer { ...... native public static void init1(String[] args); ...... public static void main(String[] args) { ...... init1(args); ...... } ...... }

SystemServer组件是由Zygote进程负责启动的，启动的时候就会调用它的main函数，这个函数主要调用了JNI方法init1来做一些系统初始化的工作。
        ##Step 2. SystemServer.init1
    
        这个函数是一个JNI方法，实现在 frameworks/base/services/jni/com_android_server_SystemServer.cpp文件中：

[cpp] view plain copy 
    namespace android {   
    
    extern "C" int system_init();  
    
    static void android_server_SystemServer_init1(JNIEnv* env, jobject clazz)  
    {  
        system_init();  
    }  
    
    /* * JNI registration. */  
    static JNINativeMethod gMethods[] = {  
        /* name, signature, funcPtr */  
        { "init1", "([Ljava/lang/String;)V", (void*) android_server_SystemServer_init1 },  
    };  
    
    int register_android_server_SystemServer(JNIEnv* env)  
    {  
        return jniRegisterNativeMethods(env, "com/android/server/SystemServer",  
                gMethods, NELEM(gMethods));  
    }  
    
    }; // namespace android

这个函数很简单，只是调用了system_init函数来进一步执行操作。
        ##Step 3. libsystem_server.system_init
    
        函数system_init实现在libsystem_server库中，源代码位于frameworks/base/cmds/system_server/library/system_init.cpp文件中：

[cpp] view plain copy 
    extern "C" status_t system_init()  
    {  
        LOGI("Entered system_init()");  
    
        sp<ProcessState> proc(ProcessState::self());  
    
        sp<IServiceManager> sm = defaultServiceManager();  
        LOGI("ServiceManager: %p\n", sm.get());  
    
        sp<GrimReaper> grim = new GrimReaper();  
        sm->asBinder()->linkToDeath(grim, grim.get(), 0);  
    
        char propBuf[PROPERTY_VALUE_MAX];  
        property_get("system_init.startsurfaceflinger", propBuf, "1");  
        if (strcmp(propBuf, "1") == 0) {  
            // Start the SurfaceFlinger 
            SurfaceFlinger::instantiate();  
        }  
    
        // Start the sensor service 
        SensorService::instantiate();  
    
        // On the simulator, audioflinger et al don't get started the 
        // same way as on the device, and we need to start them here 
        if (!proc->supportsProcesses()) {  
    
            // Start the AudioFlinger 
            AudioFlinger::instantiate();  
    
            // Start the media playback service 
            MediaPlayerService::instantiate();  
    
            // Start the camera service 
            CameraService::instantiate();  
    
            // Start the audio policy service 
            AudioPolicyService::instantiate();  
        }  
    
        // And now start the Android runtime. We have to do this bit 
        // of nastiness because the Android runtime initialization requires 
        // some of the core system services to already be started. 
        // All other servers should just start the Android runtime at 
        // the beginning of their processes's main(), before calling 
        // the init function. 
        LOGI("System server: starting Android runtime.\n");  
    
        AndroidRuntime* runtime = AndroidRuntime::getRuntime();  
    
        LOGI("System server: starting Android services.\n");  
        runtime->callStatic("com/android/server/SystemServer", "init2");  
    
        // If running in our own process, just go into the thread 
        // pool. Otherwise, call the initialization finished 
        // func to let this process continue its initilization. 
        if (proc->supportsProcesses()) {  
            LOGI("System server: entering thread pool.\n");  
            ProcessState::self()->startThreadPool();  
            IPCThreadState::self()->joinThreadPool();  
            LOGI("System server: exiting thread pool.\n");  
        }  
    
        return NO_ERROR;  
    }

这个函数首先会初始化SurfaceFlinger、SensorService、AudioFlinger、MediaPlayerService、CameraService和AudioPolicyService这几个服务，然后就通过系统全局唯一的AndroidRuntime实例变量runtime的callStatic来调用SystemServer的init2函数了。关于这个AndroidRuntime实例变量runtime的相关资料，可能参考前面一篇文章Android应用程序进程启动过程的源代码分析一文。
       ## Step 4. AndroidRuntime.callStatic
    
        这个函数定义在frameworks/base/core/jni/AndroidRuntime.cpp文件中：

[cpp] view plain copy /* * Call a static Java Programming Language function that takes no arguments and returns void. */ status_t AndroidRuntime::callStatic(const char* className, const char* methodName) { JNIEnv* env; jclass clazz; jmethodID methodId; env = getJNIEnv(); if (env == NULL) return UNKNOWN_ERROR; clazz = findClass(env, className); if (clazz == NULL) { LOGE("ERROR: could not find class '%s'\n", className); return UNKNOWN_ERROR; } methodId = env->GetStaticMethodID(clazz, methodName, "()V"); if (methodId == NULL) { LOGE("ERROR: could not find method %s.%s\n", className, methodName); return UNKNOWN_ERROR; } env->CallStaticVoidMethod(clazz, methodId); return NO_ERROR; }

这个函数调用由参数className指定的java类的静态成员函数，这个静态成员函数是由参数methodName指定的。上面传进来的参数className的值为"com/android/server/SystemServer"，而参数methodName的值为"init2"，因此，接下来就会调用SystemServer类的init2函数了。
        ##Step 5. SystemServer.init2
    
        这个函数定义在frameworks/base/services/java/com/android/server/SystemServer.java文件中：

[java] view plain copy 
    public class SystemServer  
    {  
        ......  
    
        public static final void init2() {  
            Slog.i(TAG, "Entered the Android system server!");  
            Thread thr = new ServerThread();  
            thr.setName("android.server.ServerThread");  
            thr.start();  
        }  
    }

这个函数创建了一个ServerThread线程，PackageManagerService服务就是这个线程中启动的了。这里调用了ServerThread实例thr的start函数之后，下面就会执行这个实例的run函数了。
        ##Step 6. ServerThread.run
    
        这个函数定义在frameworks/base/services/java/com/android/server/SystemServer.java文件中：

[java] view plain copy 
    class ServerThread extends Thread {   
        ......  
    
        @Override  
        public void run() {  
            ......  
    
            IPackageManager pm = null;  
    
            ......  
    
            // Critical services... 
            try {  
                ......  
    
                Slog.i(TAG, "Package Manager");  
                pm = PackageManagerService.main(context,  
                            factoryTest != SystemServer.FACTORY_TEST_OFF);  
    
                ......  
            } catch (RuntimeException e) {  
                Slog.e("System", "Failure starting core service", e);  
            }  
    
            ......  
        }  
    
        ......  
    }

这个函数除了启动PackageManagerService服务之外，还启动了其它很多的服务，例如在前面学习Activity和Service的几篇文章中经常看到的ActivityManagerService服务，有兴趣的读者可以自己研究一下。
        ##Step 7. PackageManagerService.main
    
        这个函数定义在frameworks/base/services/java/com/android/server/PackageManagerService.java文件中：

[cpp] view plain copy 
    class PackageManagerService extends IPackageManager.Stub {   
        ......  
    
        public static final IPackageManager main(Context context, boolean factoryTest) {  
            PackageManagerService m = new PackageManagerService(context, factoryTest);  
            ServiceManager.addService("package", m);  
            return m;  
        }  
    
        ......  
    }

# 3.常见的4种安装场景 #

## 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。 ##

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。

# (1)系统应用安装――开机时完成，没有安装界面 #

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

在创建这个PackageManagerService服务实例时，会在PackageManagerService类的构造函数中开始执行安装应用程序的过程：

## PackageManagerService核心代码 ##

[java] view plain copy 
    class PackageManagerService extends IPackageManager.Stub {   
        ......  
    
        public PackageManagerService(Context context, boolean factoryTest) {  
            ......  
        mSetting = new Setting();
            synchronized (mInstallLock) {  
                synchronized (mPackages) {  
                    ......  
    
                    File dataDir = Environment.getDataDirectory();  
                    mAppDataDir = new File(dataDir, "data");  
                    mSecureAppDataDir = new File(dataDir, "secure/data");  
    
            mRestoredSetting = mASetting.readLP();
    
                    mDrmAppPrivateInstallDir = new File(dataDir, "app-private");  
    
                    ......  
    
                    mFrameworkDir = new File(Environment.getRootDirectory(), "framework");  
                    mDalvikCacheDir = new File(dataDir, "dalvik-cache");  
    
                    ......  
    
                    // 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);  
    
                    // 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);  
    
                    // 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);  
    
    
                    mAppInstallObserver = new AppDirObserver(  
                        mAppInstallDir.getPath(), OBSERVER_EVENTS, false);  
                    mAppInstallObserver.startWatching();  
                    scanDirLI(mAppInstallDir, 0, scanMode, 0);  
    
                    mDrmAppInstallObserver = new AppDirObserver(  
                        mDrmAppPrivateInstallDir.getPath(), OBSERVER_EVENTS, false);  
                    mDrmAppInstallObserver.startWatching();  
                    scanDirLI(mDrmAppPrivateInstallDir, PackageParser.PARSE_FORWARD_LOCK,  
                        scanMode, 0);  
    
                    ......  
            final boolean regrantPermissions = mSetting.mInternalSDKplatform != mSdkVersion;
            updatePermissionsLP(null,null,true,rregrantPermissions .regrantPermissions );
            msetting.writeLP();
                }  
            }  
        }  
    
        ......  
    }

#这里会调用scanDirLI函数来扫描移动设备上的下面这五个目录中的Apk文件
    
        /system/framework
    
        /system/app
    
        /vendor/app
    
        /data/app
    
        /data/app-private
    
    
    由于Android每次启动的时候都需要安装一次信息，但是有些信息是保持不变的，例如Linux用户组Id，PackageManagerService 每次安装程序之后，都会把这些程序的信息保存下来，以便下次使用，

恢复上一次程序的安装信息是通过PackageManagerService 的成员变量mSetting的readLP()来实现的，恢复信息之后就开始扫描和安装app了。

#扫描安装app
    
    
       ##Step 8. PackageManagerService.scanDirLI
       这个函数定义在frameworks/base/services/java/com/android/server/PackageManagerService.java文件中：

[java] view plain copy 
    class PackageManagerService extends IPackageManager.Stub {   
        ......  
    
        private void scanDirLI(File dir, int flags, int scanMode, long currentTime) {  
            String[] files = dir.list();  
            ......  
    
            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();  
                }  
            }  
        }  
    
    
        ......  
    }

对于目录中的每一个文件，如果是以后Apk作为后缀名，那么就调用scanPackageLI函数来对它进行解析和安装。
         ##Step 9. PackageManagerService.scanPackageLI
    
         这个函数定义在frameworks/base/services/java/com/android/server/PackageManagerService.java文件中：

[java] view plain copy 在CODE上查看代码片派生到我的代码片
    class PackageManagerService extends IPackageManager.Stub {   
        ......  
    
        private PackageParser.Package scanPackageLI(File scanFile,  
                int parseFlags, int scanMode, long currentTime) {  
            ......  
    
            String scanPath = scanFile.getPath();  
            parseFlags |= mDefParseFlags;  
            PackageParser pp = new PackageParser(scanPath);  
    
            ......  
    
            final PackageParser.Package pkg = pp.parsePackage(scanFile,  
                scanPath, mMetrics, parseFlags);  
    
            ......  
    
            return scanPackageLI(pkg, parseFlags, scanMode | SCAN_UPDATE_SIGNATURE, currentTime);  
        }  
    
        ......  
    }

这个函数首先会为这个Apk文件创建一个PackageParser实例，接着调用这个实例的parsePackage函数来对这个Apk文件进行解析。这个函数最后还会调用另外一个版本的scanPackageLI函数把来解析后得到的应用程序信息保存在PackageManagerService中。
       ## Step 10. PackageParser.parsePackage
        这个函数定义在frameworks/base/core/java/android/content/pm/PackageParser.java文件中：

[java] view plain copy 在CODE上查看代码片派生到我的代码片
    public class PackageParser {  
        ......  
    
        public Package parsePackage(File sourceFile, String destCodePath,  
                DisplayMetrics metrics, int flags) {  
            ......  
    
            mArchiveSourcePath = sourceFile.getPath();  
    
            ......  
    
            XmlResourceParser parser = null;  
            AssetManager assmgr = null;  
            boolean assetError = true;  
            try {  
                assmgr = new AssetManager();  
                int cookie = assmgr.addAssetPath(mArchiveSourcePath);  
                if(cookie != 0) {  
                    parser = assmgr.openXmlResourceParser(cookie, "AndroidManifest.xml");  
                    assetError = false;  
                } else {  
                    ......  
                }  
            } catch (Exception e) {  
                ......  
            }  
    
            ......  
    
            String[] errorText = new String[1];  
            Package pkg = null;  
            Exception errorException = null;  
            try {  
                // XXXX todo: need to figure out correct configuration. 
                Resources res = new Resources(assmgr, metrics, null);  
                pkg = parsePackage(res, parser, flags, errorText);  
            } catch (Exception e) {  
                ......  
            }  
    
            ......  
    
            parser.close();  
            assmgr.close();  
    
            // Set code and resource paths 
            pkg.mPath = destCodePath;  
            pkg.mScanPath = mArchiveSourcePath;  
            //pkg.applicationInfo.sourceDir = destCodePath; 
            //pkg.applicationInfo.publicSourceDir = destRes; 
            pkg.mSignatures = null;  
    
            return pkg;  
        }  
    
        ......  
    }

每一个Apk文件都是一个归档文件，它里面包含了Android应用程序的配置文件AndroidManifest.xml，这里主要就是要对这个配置文件就行解析了，从Apk归档文件中得到这个配置文件后，就调用另一外版本的parsePackage函数对这个应用程序进行解析了：

\[java\] view plain copy 在CODE上查看代码片派生到我的代码片

public class PackageParser {  
        ......  
    
        private Package parsePackage(  
                Resources res, XmlResourceParser parser, int flags, String[] outError)  
                throws XmlPullParserException, IOException {  
            ......  
    
            String pkgName = parsePackageName(parser, attrs, flags, outError);  
    
            ......  
    
            final Package pkg = new Package(pkgName);  
    
            ......  
    
            int type; 
    
            ......  
    
            TypedArray sa = res.obtainAttributes(attrs,  
                com.android.internal.R.styleable.AndroidManifest);  
    
            ......  
    
            while ((type=parser.next()) != parser.END_DOCUMENT  
                && (type != parser.END_TAG || parser.getDepth() > outerDepth)) {  
                    if (type == parser.END_TAG || type == parser.TEXT) {  
                        continue;  
                    }  
    
                    String tagName = parser.getName();  
                    if (tagName.equals("application")) {  
                        ......  
    
                        if (!parseApplication(pkg, res, parser, attrs, flags, outError)) {  
                            return null;  
                        }  
                    } else if (tagName.equals("permission-group")) {  
                        ......  
                    } else if (tagName.equals("permission")) {  
                        ......  
                    } else if (tagName.equals("permission-tree")) {  
                        ......  
                    } else if (tagName.equals("uses-permission")) {  
                        ......  
                    } else if (tagName.equals("uses-configuration")) {  
                        ......  
                    } else if (tagName.equals("uses-feature")) {  
                        ......  
                    } else if (tagName.equals("uses-sdk")) {  
                        ......  
                    } else if (tagName.equals("supports-screens")) {  
                        ......  
                    } else if (tagName.equals("protected-broadcast")) {  
                        ......  
                    } else if (tagName.equals("instrumentation")) {  
                        ......  
                    } else if (tagName.equals("original-package")) {  
                        ......  
                    } else if (tagName.equals("adopt-permissions")) {  
                        ......  
                    } else if (tagName.equals("uses-gl-texture")) {  
                        ......  
                    } else if (tagName.equals("compatible-screens")) {  
                        ......  
                    } else if (tagName.equals("eat-comment")) {  
                        ......  
                    } else if (RIGID_PARSER) {  
                        ......  
                    } else {  
                        ......  
                    }  
            }  
    
            ......  
    
            return pkg;  
        }  
    
        ......  
    }

这里就是对AndroidManifest.xml文件中的各个标签进行解析了，各个标签的含义可以参考官方文档http://developer.android.com/guide/topics/manifest/manifest-intro.html，这里我们只简单看一下application标签的解析，这是通过调用parseApplication函数来进行的。
      ##  Step 11. PackageParser.parseApplication
        这个函数定义在frameworks/base/core/java/android/content/pm/PackageParser.java文件中：

[java] view plain copy 在CODE上查看代码片派生到我的代码片 public class PackageParser { ...... private boolean parseApplication(Package owner, Resources res, XmlPullParser parser, AttributeSet attrs, int flags, String[] outError) throws XmlPullParserException, IOException { final ApplicationInfo ai = owner.applicationInfo; final String pkgName = owner.applicationInfo.packageName; TypedArray sa = res.obtainAttributes(attrs, com.android.internal.R.styleable.AndroidManifestApplication); ...... int type; while ((type=parser.next()) != parser.END_DOCUMENT && (type != parser.END_TAG || parser.getDepth() > innerDepth)) { if (type == parser.END_TAG || type == parser.TEXT) { continue; } String tagName = parser.getName(); if (tagName.equals("activity")) { Activity a = parseActivity(owner, res, parser, attrs, flags, outError, false); ...... owner.activities.add(a); } else if (tagName.equals("receiver")) { Activity a = parseActivity(owner, res, parser, attrs, flags, outError, true); ...... owner.receivers.add(a); } else if (tagName.equals("service")) { Service s = parseService(owner, res, parser, attrs, flags, outError); ...... owner.services.add(s); } else if (tagName.equals("provider")) { Provider p = parseProvider(owner, res, parser, attrs, flags, outError); ...... owner.providers.add(p); } else if (tagName.equals("activity-alias")) { Activity a = parseActivityAlias(owner, res, parser, attrs, flags, outError); ...... owner.activities.add(a); } else if (parser.getName().equals("meta-data")) { ...... } else if (tagName.equals("uses-library")) { ...... } else if (tagName.equals("uses-package")) { ...... } else { ...... } } return true; } ...... }

这里就是对AndroidManifest.xml文件中的application标签进行解析了，我们常用到的标签就有activity、service、receiver和provider，各个标签的含义可以参考官方文档http://developer.android.com/guide/topics/manifest/manifest-intro.html。
        这里解析完成后，一层层返回到Step 9中，调用另一个版本的scanPackageLI函数把来解析后得到的应用程序信息保存下来。
    
        ##Step 12. PackageManagerService.scanPackageLI
    
        这个函数定义在frameworks/base/services/java/com/android/server/PackageManagerService.java文件中：

[java] view plain copy 在CODE上查看代码片派生到我的代码片
    class PackageManagerService extends IPackageManager.Stub {  
        ......  
    
        // Keys are String (package name), values are Package.  This also serves  
        // as the lock for the global state.  Methods that must be called with  
        // this lock held have the prefix "LP".  
        final HashMap<String, PackageParser.Package> mPackages =  
            new HashMap<String, PackageParser.Package>(); 
    
        ......  
    
        // All available activities, for your resolving pleasure.  
        final ActivityIntentResolver mActivities =  
        new ActivityIntentResolver(); 
    
        // All available receivers, for your resolving pleasure.  
        final ActivityIntentResolver mReceivers =  
            new ActivityIntentResolver(); 
    
        // All available services, for your resolving pleasure.  
        final ServiceIntentResolver mServices = new ServiceIntentResolver(); 
    
        // Keys are String (provider class name), values are Provider.  
        final HashMap<ComponentName, PackageParser.Provider> mProvidersByComponent =  
            new HashMap<ComponentName, PackageParser.Provider>(); 
    
        ......  
    
        private PackageParser.Package scanPackageLI(PackageParser.Package pkg,  
                int parseFlags, int scanMode, long currentTime) {  
            ......  
    
            synchronized (mPackages) {  
                ......  
    
                // Add the new setting to mPackages  
                mPackages.put(pkg.applicationInfo.packageName, pkg); 
    
                ......  
    
                int N = pkg.providers.size(); 
                int i; 
                for (i=0; i<N; i++) { 
                    PackageParser.Provider p = pkg.providers.get(i); 
                    p.info.processName = fixProcessName(pkg.applicationInfo.processName,  
                        p.info.processName, pkg.applicationInfo.uid); 
                    mProvidersByComponent.put(new ComponentName(p.info.packageName,  
                        p.info.name), p); 
    
                    ......  
                }  
    
                N = pkg.services.size(); 
                for (i=0; i<N; i++) { 
                    PackageParser.Service s = pkg.services.get(i); 
                    s.info.processName = fixProcessName(pkg.applicationInfo.processName,  
                        s.info.processName, pkg.applicationInfo.uid); 
                    mServices.addService(s); 
    
                    ......  
                }  
    
                N = pkg.receivers.size(); 
                r = null; 
                for (i=0; i<N; i++) { 
                    PackageParser.Activity a = pkg.receivers.get(i); 
                    a.info.processName = fixProcessName(pkg.applicationInfo.processName,  
                        a.info.processName, pkg.applicationInfo.uid); 
                    mReceivers.addActivity(a, "receiver"); 
    
                    ......  
                }  
    
                N = pkg.activities.size(); 
                for (i=0; i<N; i++) { 
                    PackageParser.Activity a = pkg.activities.get(i); 
                    a.info.processName = fixProcessName(pkg.applicationInfo.processName,  
                        a.info.processName, pkg.applicationInfo.uid); 
                    mActivities.addActivity(a, "activity"); 
    
                    ......  
                }  
    
                ......  
            }  
    
            ......  
    
            return pkg; 
        }  
    
        ......  
    }

这个函数主要就是把前面解析应用程序得到的package、provider、service、receiver和activity等信息保存在PackageManagerService服务中了。

# PackageManagerService的作用总结： #

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().

# 后面重点介绍installPackageLI，后面的额方式本质都会调用它。 #

# （2）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。

\[java\] view plain copy  
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

\[java\] view plain copy  
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

\[java\] view plain copy  
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

\[java\] view plain copy  
@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
    
    [java] view plain copy
    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。

\[java\] view plain copy  
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;  
\}

--------------------

\[java\] view plain copy  
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(）

\[java\] view plain copy  
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。 #(3)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

\[java\] view plain copy  
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

\[java\] view plain copy  
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。
    
    
    
    
    #(4)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

\[java\] view plain copy  
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

\[java\] view plain copy  
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完成安装。

对于mSetting的介绍还不完善，后续会继续补充

本文是读过下面的几篇博客和Android系统源代码情景分析之后写成的，感谢各位作者。

参考：

[http://ticktick.blog.51cto.com/823160/1669525][http_ticktick.blog.51cto.com_823160_1669525]  
[http://blog.csdn.net/hdhd588/article/details/6739281][http_blog.csdn.net_hdhd588_article_details_6739281]  
[http://blog.csdn.net/luoshengyang/article/details/6766010][http_blog.csdn.net_luoshengyang_article_details_6766010]  
《Android系统源代码情景分析》

[http_ticktick.blog.51cto.com_823160_1669525]: http://ticktick.blog.51cto.com/823160/1669525
[http_blog.csdn.net_hdhd588_article_details_6739281]: http://blog.csdn.net/hdhd588/article/details/6739281
[http_blog.csdn.net_luoshengyang_article_details_6766010]: http://blog.csdn.net/luoshengyang/article/details/6766010