Android APK应用安装原理解析之AndroidManifest使用PackageParser.parserPackage原理分析

public Package parsePackage(File sourceFile, String destCodePath,  DisplayMetrics metrics, int flags) {//最后要跑出的解析错误信息mParseError = PackageManager.INSTALL_SUCCEEDED;//获得要解析的文件的路径mArchiveSourcePath = sourceFile.getPath();//如果要解析的不是文件类型就跳过并且返回该方法if (!sourceFile.isFile()) {  Log.w(TAG, "Skipping dir: " + mArchiveSourcePath);  //更新错误信息  mParseError = PackageManager.INSTALL_PARSE_FAILED_NOT_APK;  return null;}//如果文件不是以.apk结尾并且flag没有确定一定是APK，那么也返回if (!isPackageFilename(sourceFile.getName())    && (flags&PARSE_MUST_BE_APK) != 0) {  if ((flags&PARSE_IS_SYSTEM) == 0) {    // We expect to have non-.apk files in the system dir,    // so don't warn about them.    Log.w(TAG, "Skipping non-package file: " + mArchiveSourcePath);  }  //更新错误信息  mParseError = PackageManager.INSTALL_PARSE_FAILED_NOT_APK;  return null;}if ((flags&PARSE_CHATTY) != 0 && Config.LOGD) Log.d(  TAG, "Scanning package: " + mArchiveSourcePath);XmlResourceParser parser = null;AssetManager assmgr = null;boolean assetError = true;try {  assmgr = new AssetManager();  //将一个文件添加到AssetManager中并返回一个唯一标识  int cookie = assmgr.addAssetPath(mArchiveSourcePath);  if(cookie != 0) {    //通过标识去AssetManager中找到标识对应资源中的Manifest清单文件，并返回一个XML的解析器    parser = assmgr.openXmlResourceParser(cookie, "AndroidManifest.xml");    //走到这里证明一切顺利    assetError = false;  } else {    Log.w(TAG, "Failed adding asset path:"+mArchiveSourcePath);  }} catch (Exception e) {  Log.w(TAG, "Unable to read AndroidManifest.xml of "      + mArchiveSourcePath, e);}if(assetError) {  if (assmgr != null) assmgr.close();  mParseError = PackageManager.INSTALL_PARSE_FAILED_BAD_MANIFEST;  return null;}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);  //这个是真正在解析的package的方法，是private method  pkg = parsePackage(res, parser, flags, errorText);} catch (Exception e) {  errorException = e;  mParseError = PackageManager.INSTALL_PARSE_FAILED_UNEXPECTED_EXCEPTION;}if (pkg == null) {  if (errorException != null) {    Log.w(TAG, mArchiveSourcePath, errorException);  } else {    Log.w(TAG, mArchiveSourcePath + " (at "        + parser.getPositionDescription()        + "): " + errorText[0]);  }  parser.close();  assmgr.close();  if (mParseError == PackageManager.INSTALL_SUCCEEDED) {    mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;  }  return null;}

private Package parsePackage(    Resources res, XmlResourceParser parser, int flags, String[] outError)    throws XmlPullParserException, IOException {    AttributeSet attrs = parser;    //每次调用这个方法时候清空这些变量    mParseInstrumentationArgs = null;    mParseActivityArgs = null;    mParseServiceArgs = null;    mParseProviderArgs = null;    //这里调用这个方法获得包名    String pkgName = parsePackageName(parser, attrs, flags, outError);    if (pkgName == null) {      mParseError = PackageManager.INSTALL_PARSE_FAILED_BAD_PACKAGE_NAME;      return null;    }    int type;    final Package pkg = new Package(pkgName);    boolean foundApp = false;    //从资源里获得AndroidManifest的数组    TypedArray sa = res.obtainAttributes(attrs,        com.android.internal.R.styleable.AndroidManifest);    //继续挖掘出版本号    pkg.mVersionCode = sa.getInteger(        com.android.internal.R.styleable.AndroidManifest_versionCode, 0);    //获取版本名    pkg.mVersionName = sa.getNonConfigurationString(        com.android.internal.R.styleable.AndroidManifest_versionName, 0);    if (pkg.mVersionName != null) {      pkg.mVersionName = pkg.mVersionName.intern();    }    //获得sharedUserId    String str = sa.getNonConfigurationString(        com.android.internal.R.styleable.AndroidManifest_sharedUserId, 0);    if (str != null && str.length() > 0) {      //验证包名是否符合规则      String nameError = validateName(str, true);      if (nameError != null && !"android".equals(pkgName)) {        outError[0] = "<manifest> specifies bad sharedUserId name /""          + str + "/": " + nameError;        mParseError = PackageManager.INSTALL_PARSE_FAILED_BAD_SHARED_USER_ID;        return null;      }      pkg.mSharedUserId = str.intern();      pkg.mSharedUserLabel = sa.getResourceId(          com.android.internal.R.styleable.AndroidManifest_sharedUserLabel, 0);    }    sa.recycle();    //安装的位置    pkg.installLocation = sa.getInteger(        com.android.internal.R.styleable.AndroidManifest_installLocation,        PARSE_DEFAULT_INSTALL_LOCATION);    // Resource boolean are -1, so 1 means we don't know the value.    int supportsSmallScreens = 1;    int supportsNormalScreens = 1;    int supportsLargeScreens = 1;    int resizeable = 1;    int anyDensity = 1;    int outerDepth = parser.getDepth();    //关键时刻到了，真正的开始解析了    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 (foundApp) {          if (RIGID_PARSER) {            outError[0] = "<manifest> has more than one <application>";            mParseError = PackageManager.INSTALL_PARSE_FAILED_MANIFEST_MALFORMED;            return null;          } else {            Log.w(TAG, "<manifest> has more than one <application>");            XmlUtils.skipCurrentTag(parser);            continue;          }        }        foundApp = true;        if (!parseApplication(pkg, res, parser, attrs, flags, outError)) {          return null;        }      } else if (tagName.equals("permission-group")) {        if (parsePermissionGroup(pkg, res, parser, attrs, outError) == null) {          return null;        }      } else if (tagName.equals("permission")) {        if (parsePermission(pkg, res, parser, attrs, outError) == null) {          return null;        }      } else if (tagName.equals("permission-tree")) {        if (parsePermissionTree(pkg, res, parser, attrs, outError) == null) {          return null;        }      } else if (tagName.equals("uses-permission")) {        sa = res.obtainAttributes(attrs,            com.android.internal.R.styleable.AndroidManifestUsesPermission);        // Note: don't allow this value to be a reference to a resource        // that may change.        String name = sa.getNonResourceString(            com.android.internal.R.styleable.AndroidManifestUsesPermission_name);        sa.recycle();       ...................................................       ...................................................       ...................................................篇幅有限