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();