APK的安装流程

//点击APK文件，弹起对话框，询问是否安装此应用。
File apkFile;
Intent intent = new Intent(Intent.ACTION_VIEW);
intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
intent.setDataAndType(Uri.fromFile(apkFile), "application/vnd.android.package-archive");
context.startActivity(intent);

public class PackageManagerService extends IPackageManager.Stub {
    
       private PackageParser.Package scanPackageDirtyLI(PackageParser.Package pkg, int parseFlags,
               int scanFlags, long currentTime, UserHandle user) throws PackageManagerException {
           //...
           // writer
           synchronized (mPackages) {
               // 验证已注册的ContentProvider是否有其他同名，做冲突检测。
               if ((scanFlags & SCAN_NEW_INSTALL) != 0) {
                   final int N = pkg.providers.size();
                   int i;
                   for (i=0; i<N; i++) {
                       PackageParser.Provider p = pkg.providers.get(i);
                       if (p.info.authority != null) {
                           String names[] = p.info.authority.split(";");
                           for (int j = 0; j < names.length; j++) {
                               if (mProvidersByAuthority.containsKey(names[j])) {
                                   PackageParser.Provider other = mProvidersByAuthority.get(names[j]);
                                   final String otherPackageName =
                                           ((other != null && other.getComponentName() != null) ?
                                                   other.getComponentName().getPackageName() : "?");
                                   throw new PackageManagerException(
                                           INSTALL_FAILED_CONFLICTING_PROVIDER,
                                                   "Can't install because provider name " + names[j]
                                                   + " (in package " + pkg.applicationInfo.packageName
                                                   + ") is already used by " + otherPackageName);
                               }
                           }
                       }
                   }
               }
           }
         
           if (mPlatformPackage == pkg) {
              //...
           } else {
               // This is a normal package, need to make its data directory.
               dataPath = getDataPathForPackage(pkg.packageName, 0);
               if (dataPath.exists()) {
                   //...
               } else {
                   //invoke installer to do the actual installation
                   //这里创建了应用数据目录，用于存放用户数据
                   int ret = createDataDirsLI(pkgName, pkg.applicationInfo.uid,
                                              pkg.applicationInfo.seinfo);
                   //...
               }
             
           }
         
           // We also need to dexopt any apps that are dependent on this library.  Note that
           // if these fail, we should abort the install since installing the library will
           // result in some apps being broken.
           if (clientLibPkgs != null) {
               if ((scanFlags & SCAN_NO_DEX) == 0) {
                   for (int i = 0; i < clientLibPkgs.size(); i++) {
                       PackageParser.Package clientPkg = clientLibPkgs.get(i);
                       if (performDexOptLI(clientPkg, null /* instruction sets */, forceDex,
                               (scanFlags & SCAN_DEFER_DEX) != 0, false) == DEX_OPT_FAILED) {
                           throw new PackageManagerException(INSTALL_FAILED_DEXOPT,
                                   "scanPackageLI failed to dexopt clientLibPkgs");
                       }
                   }
               }
           }
         
           // writer
           synchronized (mPackages) {
               //...
               // 以下对四大组件进行注册
               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);
                   //注册Content Provider
                   mProviders.addProvider(p);
                   //...
               }
               //...
           }
       }
       //...
   }
}

public class PackageParser {
    
     public Package parsePackage(File packageFile, int flags) throws PackageParserException {
         if (packageFile.isDirectory()) {
             return parseClusterPackage(packageFile, flags);
         } else {
             return parseMonolithicPackage(packageFile, flags);
         }
     }
     
     private Package parseClusterPackage(File packageDir, int flags) throws PackageParserException {
             //...
             
             //初始化AssetManager
             final AssetManager assets = new AssetManager();
             try {
                 //...
                 //解析Base APk，解析AndroidManifest.xml
                 final Package pkg = parseBaseApk(baseApk, assets, flags);
                 if (pkg == null) {
                     throw new PackageParserException(INSTALL_PARSE_FAILED_NOT_APK,
                             "Failed to parse base APK: " + baseApk);
                 }
     
                 //如果splitName不为空，则循环解析Split Apk
                 if (!ArrayUtils.isEmpty(lite.splitNames)) {
                     final int num = lite.splitNames.length;
                     pkg.splitNames = lite.splitNames;
                     pkg.splitCodePaths = lite.splitCodePaths;
                     pkg.splitRevisionCodes = lite.splitRevisionCodes;
                     pkg.splitFlags = new int[num];
                     pkg.splitPrivateFlags = new int[num];
     
                     for (int i = 0; i < num; i++) {
                         //解析
                         parseSplitApk(pkg, i, assets, flags);
                     }
                 }
     
                 pkg.setCodePath(packageDir.getAbsolutePath());
                 pkg.setUse32bitAbi(lite.use32bitAbi);
                 return pkg;
             } finally {
                 IoUtils.closeQuietly(assets);
             }
         }
}

public final class Installer {  
    public int dexopt(String apkPath, int uid, boolean isPublic) {  
        StringBuilder builder = new StringBuilder("dexopt");  
        builder.append(' ');  
        builder.append(apkPath);  
        builder.append(' ');  
        builder.append(uid);  
        builder.append(isPublic ? " 1" : " 0");  
        return execute(builder.toString());  
    }  
}