一、讀取url
以下內容部分引自
http://blog.csdn.net/dlmu2001/article/details/5936122http的協議細節實現并不需要WebCore來關注，WebCore要關注的是，如何設置請求的相關頭部信息，如何獲取服務器返回回來的響應體部數據。
WebKit中同http打交道的類主要是ResourceRequest，ResourceResonse，ResourceHandle*，ResourceHandleManager等，這里先介紹同請求信息維護相關的ResourceRequest.
ResourceRequest類的作用比較好理解，基本上就是維護http請求相關的信息（app或者內核都有可能設置這些信息），然后當WebCore發起http請求的時候，可以獲取這些信息，調用curl的接口設置對應的http請求字段。在這些信息中，最常用到的是url。
ResourceRequest類繼承于ResourceRequestBase類，絕大部分功能在ResourceRequestBase類中實現。
一）ResourceRequest構造：構造一個ResourceRequest對象只需要url參數就夠了，這是比較簡單的一個類，沒有維護其它類的對象或者句柄。
ResourceRequest(const String& url)；
ResourceRequest(const KURL& url)；
二）ResourceRequest對象的創建與維護
1.當用戶輸入網址，觸發qt事件，由
MainWindow(WebKitBuild/Debug/QtTestBrowser/moc_mainwindow.cpp:87<--moc_launcherwindow.cpp:145)調用
changeLocation函數（另有
openLocation等）。
由
MainWindow(Tools/QtTestBrowser/mainwindow.cpp:194)獲取地址欄中的url(
QString類型/usr/include/QtCore/qstring.h)，創建QUrl類型(
/usr/include/QtCore/qurl.h url規格化類，包括host、port、scheme等成員變量)，加載頁面(
page()->mainFrame()->load(url) page()函數是全局函數？)。
最終調用
QWebFrame::load(Source/WebKit/qt/Api/qwebframe.cpp:885)函數，在該函數中，會構造出ResourceRequest(
Source/WebCore/platform/network/qt/ResourceRequest.h繼承ResourceRequestBase
Source/WebCore/platform/network/ResourceRequestBase.cpp)對象，并將這個對象作為一個參數，調用
FrameLoader對象的load函數(Source/WebCore/loader/FrameLoader.cpp:1450)。
FrameLoader類負責將documents加載到Frames。當你點擊一個鏈接的時候，FrameLoader創建一個新的處于”policy”狀態的DocumentLoader對象，等待WebKit客戶端決定是否處理這個加載。通常WebKit客戶端會指示FrameLoader將這個加載視為一個導航（navigation），而不是阻止加載等。
DocumentLoader類中會維護這個ResourceRequest(
FrameLoader.cpp:1460)，
policyChecker()
——>checkNavigationPolicy(Source/WebCore/loader/FrameLoader.cpp:1585)
1585 policyChecker()->checkNavigationPolicy(loader->request(), loader, formState,
1586 callContinueLoadAfterNavigationPolicy, this);//回調函數？如下調用
——>m_frame->loader()->client()->dispatchDecidePolicyForNavigationAction(Source/WebCore/loader/PolicyChecker.cpp:87)
84 m_callback.set(request, formState.get(), function, argument);//callContinueLoadAfterNavigationPolicy
一旦客戶端指示FrameLoader將本次加載視為一個導航，FrameLoader就推動DocumentLoader進入”provisional”狀態，在該狀態，DocumentLoader會發起一個網絡請求，并等待以確定網絡請求將發起一個下載還是一個新的document。
——>page->d->acceptNavigationRequest（Source/WebKit/qt/WebCoreSupport/FrameLoaderClientQt.cpp:1271）
callPolicyFunction(Source/WebKit/qt/WebCoreSupport/FrameLoaderClientQt.cpp:1283)
回調函數？如上
//——>(m_frame->loader()->policyChecker()->*function)(action) (245)
——>callback.call(Source/WebCore/loader/PolicyChecker.cpp:160)
——>m_navigationFunction(Source/WebCore/loader/PolicyCallback.cpp:103)
——>loader->continueLoadAfterNavigationPolicy(Source/WebCore/loader/FrameLoader.cpp:2977)
2974 void FrameLoader::callContinueLoadAfterNavigationPolicy(void* argument,
2975 const ResourceRequest& request, PassRefPtr<FormState> formState, bool shouldContinue)
2976 
{
2977 FrameLoader* loader = static_cast<FrameLoader*>(argument);
2978 loader->continueLoadAfterNavigationPolicy(request, formState, shouldContinue);
2979 }
——>continueLoadAfterWillSubmitForm(Source/WebCore/loader/FrameLoader.cpp:3105)
——>m_provisionalDocumentLoader->startLoadingMainResource(Source/WebCore/loader/FrameLoader.cpp:2572)
接下去，DocumentLoader會創建一個MainResourceLoader對象，這個對象主要用來通過ResourceHandle接口同平臺網絡庫進行交互。將MainResourceLoader和DocumentLoader分開來主要有兩個目的：（1）MainResourceLoader讓DocumentLoader從處理ResourceHandle回調的細節中抽身出來（2）降低MainResourceLoader的生命周期和DocumentLoader的生命周期（同Document綁定）的耦合度。
——>m_mainResourceLoader->load(Source/WebCore/loader/DocumentLoader.cpp:798)
——>loadNow(Source/WebCore/loader/MainResourceLoader.cpp:612)
——>ResourceHandle::create(Source/WebCore/loader/MainResourceLoader.cpp:585)
——>newHandle->start(Source/WebCore/platform/network/ResourceHandle.cpp:71)
——>new QNetworkReplyHandler(Source/WebCore/platform/network/qt/ResourceHandleQt.cpp:100)
——>r.toNetworkRequest(Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:399) 設置http頭
——>m_queue.push 提交事件？ (Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:401)
——>flush();(Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:164)
——>(m_replyHandler->*(m_enqueuedCalls.takeFirst()))(); （Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:195）
——>QNetworkReplyHandler::start() (Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:659)
建立連接(ESTABLISHED)、發送請求 665： QNetworkReply* reply = sendNetworkRequest(d->m_context->networkAccessManager(), d->m_firstRequest);
——>601 WebCore::QNetworkReplyHandler::sendNetworkRequest
——>626 manager->get(m_request)
665 QNetworkReply* reply = sendNetworkRequest(d->m_context->networkAccessManager(), d->m_firstRequest);
669 m_replyWrapper = new QNetworkReplyWrapper(&m_queue, reply, m_resourceHandle->shouldContentSniff() && d->m_context-
>mimeSniffingEnabled(), this);
——>208 QNetworkReplyWrapper::QNetworkReplyWrapper(QNetworkReplyHandlerCallQueue* queue, QNetworkReply* reply, bool
sniffMIMETypes, QObject* parent)
209 : QObject(parent)
210 , m_reply(reply)
211 , m_queue(queue)
212 , m_responseContainsData(false)
213 , m_sniffMIMETypes(sniffMIMETypes)
214 {
215 Q_ASSERT(m_reply);
216
217 // setFinished() must be the first that we connect, so isFinished() is updated when running other slots.
//QT通過此種方式異步回調??(yes, 信號、槽機制，http://www.ibm.com/developerworks/cn/linux/guitoolkit/qt/signal-slot/ )
218 connect(m_reply, SIGNAL(finished()), this, SLOT(setFinished()));
219 connect(m_reply, SIGNAL(finished()), this, SLOT(receiveMetaData()));
220 connect(m_reply, SIGNAL(readyRead()), this, SLOT(receiveMetaData()));
221 }
一旦加載系統接收到足夠的信息可以確定資源確實代表了document，FrameLoader就將DocumentLoader推向”committed”狀態，在該狀態中，frame將顯示document。
下載完了之后
——>QtMIMETypeSniffer::qt_metacall() (WebKitBuild/Debug/WebCore/moc_QtMIMETypeSniffer.cpp:77)
——>trySniffing()(Source/WebCore/platform/network/qt/QtMIMETypeSniffer.cpp:59)
——>m_sniffer.sniff(data.constData(), data.size())(Source/WebCore/platform/network/qt/QtMIMETypeSniffer.cpp:51)
50 QByteArray data = m_reply->peek(m_sniffer.dataSize());
51 const char* sniffedMimeType = m_sniffer.sniff(data.constData(), data.size()); data.constData()保存著網頁內容，涉及的變量包括m_reply、m_sniffer
——>emit finished (Source/WebCore/platform/network/qt/QtMIMETypeSniffer.cpp:65)
——>QMetaObject::activate(WebKitBuild/Debug/WebCore/moc_QtMIMETypeSniffer.cpp:88)
……
WebCore::QNetworkReplyWrapper::qt_metacall (WebKitBuild/Debug/WebCore/moc_QNetworkReplyHandler.cpp)
77 if (_c == QMetaObject::InvokeMetaMethod) {
78 switch (_id) {
79 case 0: receiveMetaData(); break;
80 case 1: didReceiveFinished(); break;
81 case 2: didReceiveReadyRead(); break;
82 case 3: receiveSniffedMIMEType(); break;
83 case 4: setFinished(); break;
84 default: ;
85 }
86 _id -= 5;
87 }
——>receiveSniffedMIMEType()(WebKitBuild/Debug/WebCore/moc_QNetworkReplyHandler.cpp:82)
——>emitMetaDataChanged()(Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:305)
——>QueueLocker lock(m_queue)(Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp)
——>~QueueLocker() { m_queue->unlock(); } (203)
——>flush();(178)
——>(m_replyHandler->*(m_enqueuedCalls.takeFirst()))(); （195）
——>1、QNetworkReplyHandler::forwardData (572)
——>client->didReceiveData(m_resourceHandle, data.constData(), data.length(), -1); (586)
——>ResourceLoader::didReceiveData(ResourceHandle*, const char* data, int length, int encodedDataLength) (Source/WebCore/loader/ResourceLoader.cpp:427)
data指向保存頁面內容
——>MainResourceLoader::didReceiveData (Source/WebCore/loader/MainResourceLoader.cpp:431)
——>ResourceLoader::didReceiveData (Source/WebCore/loader/ResourceLoader.cpp:267)
279 addData(data, length, allAtOnce);
280 // FIXME: If we get a resource with more than 2B bytes, this code won't do the right thing.
281 // However, with today's computers and networking speeds, this won't happen in practice.
282 // Could be an issue with a giant local file.
283 if (m_sendResourceLoadCallbacks && m_frame)
284 frameLoader()->notifier()->didReceiveData(this, data, length, static_cast<int>(encodedDataLength)); 保存頁面到cache 函數： addData()
——>ResourceLoadNotifier::didReceiveData (Source/WebCore/loader/ResourceLoadNotifier.cpp:77)
——>ResourceLoadNotifier::dispatchDidReceiveContentLength (133)
——>InspectorInstrumentation::didReceiveContentLength （Source/WebCore/inspector/InspectorInstrumentation.h：713）
——>InspectorInstrumentation::didReceiveContentLengthImpl （Source/WebCore/inspector/InspectorInstrumentation.cpp：487）
html解析
——>2、QNetworkReplyHandler::finish(Source/WebCore/platform/network/qt/QNetworkReplyHandler.cpp:437)
——>ResourceLoader::didFinishLoading (Source/WebCore/loader/ResourceLoader.cpp:434)
——>MainResourceLoader::didFinishLoading (Source/WebCore/loader/MainResourceLoader.cpp:466)
——>FrameLoader::finishedLoading (Source/WebCore/loader/FrameLoader.cpp：2287)
——>DocumentLoader::finishedLoading (Source/WebCore/loader/DocumentLoader.cpp:282)
——>FrameLoader::finishedLoadingDocument(DocumentLoader* loader) (Source/WebCore/loader/FrameLoader.cpp:2333)
——>FrameLoaderClientQt::finishedLoading(DocumentLoader* loader) (Source/WebKit/qt/WebCoreSupport/FrameLoaderClientQt.cpp:626)
——>DocumentWriter::end() (Source/WebCore/loader/DocumentWriter.cpp:211)
211 void DocumentWriter::end()
212 {
213 m_frame->loader()->didEndDocument();
214 endIfNotLoadingMainResource();
215 } 213 ——>Document::finishParsing() (Source/WebCore/dom/Document.cpp:2246)
214： DocumentWriter::endIfNotLoadingMainResource() （Source/WebCore/loader/DocumentWriter.cpp 228）
228 addData(0, 0, true);
229 m_frame->document()->finishParsing(); ——>DocumentWriter::addData() (208)
——>DecodedDataDocumentParser::appendBytes(DocumentWriter* writer , const char* data, int length, bool shouldFlush) （Source/WebCore/dom/DecodedDataDocumentParser.cpp：40）
——> HTMLDocumentParser::append(const SegmentedString& source) (Source/WebCore/html/parser/HTMLDocumentParser.cpp:367)
——> HTMLDocumentParser::pumpTokenizerIfPossible(SynchronousMode mode) (175)
——> HTMLDocumentParser::pumpTokenizer(SynchronousMode mode) (261)
解析、執行script
——> HTMLDocumentParser::canTakeNextToken(SynchronousMode mode, PumpSession& session) (223)
——> HTMLDocumentParser::runScriptsForPausedTreeBuilder() (205)
——> HTMLScriptRunner::execute(PassRefPtr<Element> scriptElement, const TextPosition1& scriptStartPosition) Source/WebCore/html/parser/HTMLScriptRunner.cpp:167)
——> WebCore::HTMLScriptRunner::runScript(this=0x81e2a58, script=0x832c040, scriptStartPosition=...) (296)
——> WebCore::ScriptElement::prepareScript (this=0x832c084, scriptStartPosition=..., supportLegacyTypes=WebCore::ScriptElement::DisallowLegacyTypeInTypeAttribute) (Source/WebCore/dom/ScriptElement.cpp:240)
——> WebCore::ScriptElement::executeScript (this=0x832c084, sourceCode=...) (283)
——> WebCore::ScriptController::evaluate (this=0x828d1a4, sourceCode=...) (Source/WebCore/bindings/js/ScriptController.cpp:166)
——> WebCore::ScriptController::evaluateInWorld (143)
——> WebCore::JSMainThreadExecState::evaluate (Source/WebCore/bindings/js/JSMainThreadExecState.h:54)
——> JSC::evaluate(exec=0xae3f499c, scopeChain=0xae3ee5c8, source=..., thisValue=...) (Source/JavaScriptCore/runtime/Completion.cpp:64)
——> JSC::Interpreter::execute (Source/JavaScriptCore/interpreter/Interpreter.cpp:767)
——> JSC::JITCode::execute (Source/JavaScriptCore/jit/JITCode.h:77)
——> ?? ()
——> WebCore::jsHTMLDocumentPrototypeFunctionWrite(WebCore/generated/JSHTMLDocument.cpp:445)
——> WebCore::JSHTMLDocument::write (Source/WebCore/bindings/js/JSHTMLDocumentCustom.cpp:161)
——> WebCore::documentWrite (156)
——> WebCore::Document::write (Source/WebCore/dom/Document.cpp:2227)
——> WebCore::HTMLDocumentParser::insert (Source/WebCore/html/parser/HTMLDocumentParser.cpp:324)
回到了html的解析
——> WebCore::HTMLDocumentParser::pumpTokenizerIfPossible (175)
——> WebCore::HTMLDocumentParser::pumpTokenizer (299)
查看是否有script，1、如果有，轉到“ 解析、執行script”；2、如果沒有轉到下面“”
完成解析html
InspectorInstrumentation::didWriteHTML(cookie, m_tokenizer->lineNumber());
——> InspectorInstrumentation::didWriteHTML (Source/WebCore/inspector/InspectorInstrumentation.h:803)
——>
——> Document::finishParsing() (Source/WebCore/dom/Document.cpp:2259)
——>HTMLDocumentParser::finish() (Source/WebCore/html/parser/HTMLDocumentParser.cpp:427)
——>HTMLDocumentParser::attemptToEnd() (399)
——>
生成dom樹
附件(js)下載、解析
二、下載
三、加載
參考文檔
1.官方文檔：http://www.webkit.org/blog/1188/how-webkit-loads-a-web-page/
2.dlmu2001的譯文：http://blog.csdn.net/dlmu2001/article/details/5941432
3.dlmu200：WebCore中的http請求信息維護 http://blog.csdn.net/dlmu2001/article/details/59361221
4.其他技術性文章：Introduction to WebKit Objective-C Programming Guide http://developer.apple.com/library/mac/#documentation/Cocoa/Conceptual/DisplayWebContent/DisplayWebContent.html
5.其他技術性文章：Introduction to WebKit DOM Programming Topics http://developer.apple.com/library/mac/#documentation/AppleApplications/Conceptual/SafariJSProgTopics/WebKitJavaScript.html
6. http://www.webkit.org/coding/technical-articles.html
相關技巧
1.cscope查找類的定義：cs find e class.*QString[^;]*($|{)