android PakageManagerService启动流程分析详解手机开发

“android“该Package与系统有非常重要的作用，这里保存特殊处理保存该Package的信息，主要是为了提高运行过程中的效率，例如ChooserActivity使用的地方非常多。
接下里scanPackageDirtyLI方法会对系统其它的Package做处理,关键源码如下：

//mPackages用于保存系统内的所有Package，以packageName为key 
 if (mPackages.containsKey(pkg.packageName) 
                || mSharedLibraries.containsKey(pkg.packageName)) { 
           //... 
                   } 
 
        if ((scanFlags & SCAN_REQUIRE_KNOWN) != 0) { 
            if (mExpectingBetter.containsKey(pkg.packageName)) { 
                logCriticalInfo(Log.WARN, 
                        "Relax SCAN_REQUIRE_KNOWN requirement for package " + pkg.packageName); 
            } else { 
                PackageSetting known = mSettings.peekPackageLPr(pkg.packageName); 
                if (known != null) { 
                    if (DEBUG_PACKAGE_SCANNING) { 
                        Log.d(TAG, "Examining " + pkg.codePath 
                                + " and requiring known paths " + known.codePathString 
                                + " & " + known.resourcePathString); 
                    } 
                    if (!pkg.applicationInfo.getCodePath().equals(known.codePathString) 
                            || !pkg.applicationInfo.getResourcePath().equals(known.resourcePathString)) { 
                        throw new PackageManagerException(INSTALL_FAILED_PACKAGE_CHANGED, 
                                "Application package " + pkg.packageName 
                                + " found at " + pkg.applicationInfo.getCodePath() 
                                + " but expected at " + known.codePathString + "; ignoring."); 
                    } 
                } 
            } 
        } 
 
        // Initialize package source and resource directories 
        File destCodeFile = new File(pkg.applicationInfo.getCodePath()); 
        File destResourceFile = new File(pkg.applicationInfo.getResourcePath()); 
 
        SharedUserSetting suid = null; 
        PackageSetting pkgSetting = null; 
 
        if (!isSystemApp(pkg)) { 
            // Only system apps can use these features. 
            pkg.mOriginalPackages = null; 
            pkg.mRealPackage = null; 
            pkg.mAdoptPermissions = null; 
        } 
        //... 
        final String pkgName = pkg.packageName; 
 
        final long scanFileTime = scanFile.lastModified(); 
        final boolean forceDex = (scanFlags & SCAN_FORCE_DEX) != 0; 
        //确定运行该package的进程名，一般用package作为进程名 
        pkg.applicationInfo.processName = fixProcessName( 
                pkg.applicationInfo.packageName, 
                pkg.applicationInfo.processName, 
                pkg.applicationInfo.uid); 
 
        File dataPath; 
        if (mPlatformPackage == pkg) { 
            // The system package is special. 
            dataPath = new File(Environment.getDataDirectory(), "system"); 
 
            pkg.applicationInfo.dataDir = dataPath.getPath(); 
 
        } else { 
            // This is a normal package, need to make its data directory. 
            //该函数返回data/data/packageName 
            dataPath = Environment.getDataUserPackageDirectory(pkg.volumeUuid, 
                    UserHandle.USER_OWNER, pkg.packageName); 
 
            boolean uidError = false; 
            if (dataPath.exists()) { 
                //.. 
            } else { 
                if (DEBUG_PACKAGE_SCANNING) { 
                    if ((parseFlags & PackageParser.PARSE_CHATTY) != 0) 
                        Log.v(TAG, "Want this data dir: " + dataPath); 
                } 
                //该方法调用installer发送install命令，其实就是在/data/data/目录下建立packageName目录 
                //然后为系统所有的user安装此apk 
                int ret = createDataDirsLI(pkg.volumeUuid, pkgName, pkg.applicationInfo.uid, 
                        pkg.applicationInfo.seinfo); 
                //安装错误 
                if (ret < 0) { 
                    // Error from installer 
                    throw new PackageManagerException(INSTALL_FAILED_INSUFFICIENT_STORAGE, 
                            "Unable to create data dirs [errorCode=" + ret + "]"); 
                } 
 
            } 
 
            pkgSetting.uidError = uidError; 
        } 
 
        final String path = scanFile.getPath(); 
        final String cpuAbiOverride = deriveAbiOverride(pkg.cpuAbiOverride, pkgSetting); 
        //在/data/data/pageName/lib下建立和CPU类型对应的目录，例如ARM平台的事arm/,MIP平台的事mips/ 
        if ((scanFlags & SCAN_NEW_INSTALL) == 0) { 
            derivePackageAbi(pkg, scanFile, cpuAbiOverride, true /* extract libs */); 
 
            //系统package的native库统一放在/system/lib下， 
            //所以系统不会提取系统package目录apk包中的native库 
            if (isSystemApp(pkg) && !pkg.isUpdatedSystemApp() && 
                    pkg.applicationInfo.primaryCpuAbi == null) { 
                setBundledAppAbisAndRoots(pkg, pkgSetting); 
                setNativeLibraryPaths(pkg); 
            } 
 
        } else { 
            if ((scanFlags & SCAN_MOVE) != 0) { 
            // 
            setNativeLibraryPaths(pkg); 
        } 
        //... 
        if ((scanFlags & SCAN_NO_DEX) == 0) { 
            //对该APK做dex优化 
            int result = mPackageDexOptimizer.performDexOpt(pkg, null /* instruction sets */, 
                    forceDex, (scanFlags & SCAN_DEFER_DEX) != 0, false /* inclDependencies */); 
      //如果该apk已经存在，要先杀掉该APK的进程 
         if ((scanFlags & SCAN_REPLACING) != 0) { 
            killApplication(pkg.applicationInfo.packageName, 
                        pkg.applicationInfo.uid, "replace pkg"); 
        } 
        //在此之前，四大组件信息都是Package对象的私有的，在这里把它们注册到PKM内部的财产管理对象中。 
        //这样，PKMS就可对外提供统一的组件信息。 
        synchronized (mPackages) { 
                ... 
            //注册该Package中的provider到PKM的mProviders上 
            int N = pkg.providers.size(); 
            StringBuilder r = null; 
            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); 
                mProviders.addProvider(p); 
                p.syncable = p.info.isSyncable; 
                if (p.info.authority != null) { 
                   //...            
                    } 
            //注册该Package中的service到PKM的mServices上 
            N = pkg.services.size(); 
            r = null; 
            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); 
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) { 
                    if (r == null) { 
                        r = new StringBuilder(256); 
                    } else { 
                        r.append(' '); 
                    } 
                    r.append(s.info.name); 
                } 
            } 
            if (r != null) { 
                if (DEBUG_PACKAGE_SCANNING) Log.d(TAG, "  Services: " + r); 
            } 
            //注册该Package中的receiver到PKM的mReceivers上 
            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"); 
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) { 
                    if (r == null) { 
                        r = new StringBuilder(256); 
                    } else { 
                        r.append(' '); 
                    } 
                    r.append(a.info.name); 
                } 
            } 
            if (r != null) { 
                if (DEBUG_PACKAGE_SCANNING) Log.d(TAG, "  Receivers: " + r); 
            } 
            //注册该Package中的activity到PKM的mActivities上 
            N = pkg.activities.size(); 
            r = null; 
            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"); 
                if ((parseFlags&PackageParser.PARSE_CHATTY) != 0) { 
                    if (r == null) { 
                        r = new StringBuilder(256); 
                    } else { 
                        r.append(' '); 
                    } 
                    r.append(a.info.name); 
                } 
            } 
            if (r != null) { 
                if (DEBUG_PACKAGE_SCANNING) Log.d(TAG, "  Activities: " + r); 
            } 
            //... 
          return pkg; 
    } 
 

        if (!mOnlyCore) { 
                EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_DATA_SCAN_START, 
                        SystemClock.uptimeMillis()); 
                scanDirLI(mAppInstallDir, 0, scanFlags | SCAN_REQUIRE_KNOWN, 0); 
 
                scanDirLI(mDrmAppPrivateInstallDir, PackageParser.PARSE_FORWARD_LOCK, 
                        scanFlags | SCAN_REQUIRE_KNOWN, 0); 
        } 
 

            //整理更新Permisssion的信息 
            updatePermissionsLPw(null, null, updateFlags); 
            //... 
 
            //将信息写到package.xml，pacakage.list和package-stopped.xml中 
            mSettings.writeLPr(); 
 
            EventLog.writeEvent(EventLogTags.BOOT_PROGRESS_PMS_READY, 
                    SystemClock.uptimeMillis()); 
 
            mRequiredVerifierPackage = getRequiredVerifierLPr(); 
            mRequiredInstallerPackage = getRequiredInstallerLPr(); 
 
        } // synchronized (mPackages) 
        } // synchronized (mInstallLock) 
 
        //gc 
        Runtime.getRuntime().gc();