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public class R { public static class layout { public static final int activity_main = 0x7f020000 }}

<?xml version="1.0" encoding="utf-8"?><ImageView xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="@android:color/black"></ImageView>

#define Res_GETPACKAGE(id) ((id>>24)-1)#define Res_GETTYPE(id) (((id>>16)&0xFF)-1)#define Res_GETENTRY(id) (id&0xFFFF)
#define APP_PACKAGE_ID 0x7f#define SYS_PACKAGE_ID 0x01

<?xml version="1.0" encoding="utf-8"?><ImageView xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:src="@com.google.android.webview:drawable/icon_webview"></ImageView>

bool createIfNotFound = false;const char16_t* resourceRefName;int resourceNameLen;if (len > 2 && s[1] == '+') { createIfNotFound = true; resourceRefName = s + 2; resourceNameLen = len - 2;} else if (len > 2 && s[1] == '*') { enforcePrivate = false; resourceRefName = s + 2; resourceNameLen = len - 2;} else { createIfNotFound = false; resourceRefName = s + 1; resourceNameLen = len - 1;}String16 package, type, name;if (!expandResourceRef(resourceRefName,resourceNameLen, &package, &type, &name, defType, defPackage, &errorMsg)) { if (accessor != NULL) { accessor->reportError(accessorCookie, errorMsg); } return false;}
uint32_t specFlags = 0;uint32_t rid = identifierForName(name.string(), name.size(), type.string(), type.size(), package.string(), package.size(), &specFlags);if (rid != 0) { if (enforcePrivate) { if (accessor == NULL || accessor->getAssetsPackage() != package) { if ((specFlags&ResTable_typeSpec::SPEC_PUBLIC) == 0) { if (accessor != NULL) { accessor->reportError(accessorCookie, "Resource is not public."); } return false; } } } // ...}

<?xml version="1.0" encoding="utf-8"?><ImageView xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:src="@*com.google.android.webview:drawable/icon_webview"></ImageView>

if (accessor) { rid = Res_MAKEID( accessor->getRemappedPackage(Res_GETPACKAGE(rid)), Res_GETTYPE(rid), Res_GETENTRY(rid)); if (kDebugTableNoisy) { ALOGI("Incl %s:%s/%s: 0x%08x\n", String8(package).string(), String8(type).string(), String8(name).string(), rid); }}
uint32_t packageId = Res_GETPACKAGE(rid) + 1;if (packageId != APP_PACKAGE_ID && packageId != SYS_PACKAGE_ID) { outValue->dataType = Res_value::TYPE_DYNAMIC_REFERENCE;}outValue->data = rid;

status_t DynamicRefTable::lookupResourceId(uint32_t* resId) const { uint32_t res = *resId; size_t packageId = Res_GETPACKAGE(res) + 1;
 if (packageId == APP_PACKAGE_ID && !mAppAsLib) { // No lookup needs to be done, app package IDs are absolute. return NO_ERROR; }
 if (packageId == 0 || (packageId == APP_PACKAGE_ID && mAppAsLib)) { // The package ID is 0x00. That means that a shared library is accessing // its own local resource. // Or if app resource is loaded as shared library, the resource which has // app package Id is local resources. // so we fix up those resources with the calling package ID. *resId = (0xFFFFFF & (*resId)) | (((uint32_t) mAssignedPackageId) << 24); return NO_ERROR; }
 // Do a proper lookup. uint8_t translatedId = mLookupTable[packageId]; if (translatedId == 0) { ALOGW("DynamicRefTable(0x%02x): No mapping for build-time package ID 0x%02x.", (uint8_t)mAssignedPackageId, (uint8_t)packageId); for (size_t i = 0; i < 256; i++) { if (mLookupTable[i] != 0) { ALOGW("e[0x%02x] -> 0x%02x", (uint8_t)i, mLookupTable[i]); } } return UNKNOWN_ERROR; }
 *resId = (res & 0x00ffffff) | (((uint32_t) translatedId) << 24); return NO_ERROR;}

void AssetManager2::BuildDynamicRefTable() { package_groups_.clear(); package_ids_.fill(0xff);
 // 0x01 is reserved for the android package. int next_package_id = 0x02; const size_t apk_assets_count = apk_assets_.size(); for (size_t i = 0; i < apk_assets_count; i++) { const ApkAssets* apk_asset = apk_assets_[i]; for (const std::unique_ptr<const LoadedPackage>& package : apk_asset->GetLoadedArsc()->GetPackages()) { // Get the package ID or assign one if a shared library. int package_id; if (package->IsDynamic()) { //在 LoadedArsc 中，发现如果 packageId == 0，就被定义为 DynamicPackage package_id = next_package_id++; } else { //否则使用自己定义的 packageId （非0） package_id = package->GetPackageId(); }
 // Add the mapping for package ID to index if not present. uint8_t idx = package_ids_[package_id]; if (idx == 0xff) { // 把这个 packageId 记录下来，并赋值进内存中和 package 绑定起来 package_ids_[package_id] = idx = static_cast<uint8_t>(package_groups_.size()); package_groups_.push_back({}); package_groups_.back().dynamic_ref_table.mAssignedPackageId = package_id; } PackageGroup* package_group = &package_groups_[idx];
 // Add the package and to the set of packages with the same ID. package_group->packages_.push_back(package.get()); package_group->cookies_.push_back(static_cast<ApkAssetsCookie>(i));
 // 同时更改 DynamicRefTable 中 包名 和 packageId 的对应关系 // Add the package name -> build time ID mappings. for (const DynamicPackageEntry& entry : package->GetDynamicPackageMap()) { String16 package_name(entry.package_name.c_str(), entry.package_name.size()); package_group->dynamic_ref_table.mEntries.replaceValueFor( package_name, static_cast<uint8_t>(entry.package_id)); } } }

 // 使用 O(n^2) 的方式，把已经缓存的所有 DynamicRefTable 中的 包名 -> id 的关系全部重映射一遍
 // Now assign the runtime IDs so that we have a build-time to runtime ID map. const auto package_groups_end = package_groups_.end(); for (auto iter = package_groups_.begin(); iter != package_groups_end; ++iter) { const std::string& package_name = iter->packages_[0]->GetPackageName(); for (auto iter2 = package_groups_.begin(); iter2 != package_groups_end; ++iter2) { iter2->dynamic_ref_table.addMapping(String16(package_name.c_str(), package_name.size()), iter->dynamic_ref_table.mAssignedPackageId); } }}