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FrameLoader类负责将documents加载到Frames。当你点击一个链接的时候,FrameLoader创建一个新的处于”policy”状态的DocumentLoader对象,等待WebKit客户端决定是否处理这个加载。通常WebKit客户端会指示FrameLoader将这个加载视为一个导航(navigation),而不是阻止加载等。
DocumentLoader 类中会维护这个ResourceRequest( FrameLoader.cpp :1460), policyChecker()一旦客户端指示FrameLoader将本次加载视为一个导航,FrameLoader就推动DocumentLoader进入”provisional”状态,在该状态,DocumentLoader会发起一个网络请求,并等待以确定网络请求将发起一个下载还是一个新的document。
——>page->d->acceptNavigationRequest(Source/WebKit/qt/WebCoreSupport/FrameLoaderClientQt.cpp:1271)
callPolicyFunction(Source/WebKit/qt/WebCoreSupport/FrameLoaderClientQt.cpp:1283)
回调函数?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)
——>continueLoadAfterWillSubmitForm(Source/WebCore/loader/FrameLoader.cpp:3105)
——>m_provisionalDocumentLoader->startLoadingMainResource(Source/WebCore/loader/FrameLoader.cpp:2572)
接下去,DocumentLoader会创建一个MainResourceLoader对象,这个对象主要用来通过ResourceHandle接口同平台网络库进行交互。将MainResourceLoader和DocumentLoader分开来主要有两个目的:(1)MainResourceLoader让DocumentLoader从处理ResourceHandle回调的细节中抽身出来(2)降低MainResourceLoader的生命周期和DocumentLoader的生命周期(同Document绑定)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) 设置http头
——>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)
建立连接(ESTABLISHED)、发送请求 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通过此种方式异步回调??(yes, 信号、槽机制,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 }
一旦加载系统接收到足够的信息可以确定资源确实代表了document,FrameLoader就将DocumentLoader推向”committed”状态,在该状态中,frame将显示document。
下载完了之后
——>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)
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