谷歌浏览器的源码分析(22)

上一次说到消息转发，并分析了RenderThread类里处理消息的函数，其实大部份的消息都是在RenderView类里的OnMessageReceived函数处理，比如浏览的消息也是在这里处理。它的代码如下：

#001 void RenderView::OnMessageReceived(const IPC::Message& message) {

#002 // Let the resource dispatcher intercept resource messages first.

如果是资源消息，就直接分发去处理，以便提高效率。

#003 if (resource_dispatcher_->OnMessageReceived(message))

#004 return;

下面开始处理RenderView类里所有的消息。

#005 IPC_BEGIN_MESSAGE_MAP(RenderView, message)

#006 IPC_MESSAGE_HANDLER(ViewMsg_CreatingNew_ACK, OnCreatingNewAck)

#007 IPC_MESSAGE_HANDLER(ViewMsg_CaptureThumbnail, SendThumbnail)

#008 IPC_MESSAGE_HANDLER(ViewMsg_GetPrintedPagesCount, OnGetPrintedPagesCount)

#009 IPC_MESSAGE_HANDLER(ViewMsg_PrintPages, OnPrintPages)

#010 IPC_MESSAGE_HANDLER(ViewMsg_Navigate, OnNavigate)

#011 IPC_MESSAGE_HANDLER(ViewMsg_Stop, OnStop)

#012 IPC_MESSAGE_HANDLER(ViewMsg_LoadAlternateHTMLText, OnLoadAlternateHTMLText)

#013 IPC_MESSAGE_HANDLER(ViewMsg_StopFinding, OnStopFinding)

#014 IPC_MESSAGE_HANDLER(ViewMsg_Undo, OnUndo)

#015 IPC_MESSAGE_HANDLER(ViewMsg_Redo, OnRedo)

#016 IPC_MESSAGE_HANDLER(ViewMsg_Cut, OnCut)

#017 IPC_MESSAGE_HANDLER(ViewMsg_Copy, OnCopy)

#018 IPC_MESSAGE_HANDLER(ViewMsg_Paste, OnPaste)

#019 IPC_MESSAGE_HANDLER(ViewMsg_Replace, OnReplace)

#020 IPC_MESSAGE_HANDLER(ViewMsg_Delete, OnDelete)

#021 IPC_MESSAGE_HANDLER(ViewMsg_SelectAll, OnSelectAll)

#022 IPC_MESSAGE_HANDLER(ViewMsg_CopyImageAt, OnCopyImageAt)

#023 IPC_MESSAGE_HANDLER(ViewMsg_Find, OnFind)

#024 IPC_MESSAGE_HANDLER(ViewMsg_AlterTextSize, OnAlterTextSize)

#025 IPC_MESSAGE_HANDLER(ViewMsg_SetPageEncoding, OnSetPageEncoding)

#026 IPC_MESSAGE_HANDLER(ViewMsg_InspectElement, OnInspectElement)

#027 IPC_MESSAGE_HANDLER(ViewMsg_ShowJavaScriptConsole, OnShowJavaScriptConsole)

#028 IPC_MESSAGE_HANDLER(ViewMsg_DownloadImage, OnDownloadImage)

#029 IPC_MESSAGE_HANDLER(ViewMsg_ScriptEvalRequest, OnScriptEvalRequest)

#030 IPC_MESSAGE_HANDLER(ViewMsg_AddMessageToConsole, OnAddMessageToConsole)

#031 IPC_MESSAGE_HANDLER(ViewMsg_DebugAttach, OnDebugAttach)

#032 IPC_MESSAGE_HANDLER(ViewMsg_DebugDetach, OnDebugDetach)

#033 IPC_MESSAGE_HANDLER(ViewMsg_ReservePageIDRange, OnReservePageIDRange)

#034 IPC_MESSAGE_HANDLER(ViewMsg_UploadFile, OnUploadFileRequest)

#035 IPC_MESSAGE_HANDLER(ViewMsg_FormFill, OnFormFill)

#036 IPC_MESSAGE_HANDLER(ViewMsg_FillPasswordForm, OnFillPasswordForm)

#037 IPC_MESSAGE_HANDLER(ViewMsg_DragTargetDragEnter, OnDragTargetDragEnter)

#038 IPC_MESSAGE_HANDLER(ViewMsg_DragTargetDragOver, OnDragTargetDragOver)

#039 IPC_MESSAGE_HANDLER(ViewMsg_DragTargetDragLeave, OnDragTargetDragLeave)

#040 IPC_MESSAGE_HANDLER(ViewMsg_DragTargetDrop, OnDragTargetDrop)

#041 IPC_MESSAGE_HANDLER(ViewMsg_AllowDomAutomationBindings,

#042 OnAllowDomAutomationBindings)

#043 IPC_MESSAGE_HANDLER(ViewMsg_AllowBindings, OnAllowBindings)

#044 IPC_MESSAGE_HANDLER(ViewMsg_SetDOMUIProperty, OnSetDOMUIProperty)

#045 IPC_MESSAGE_HANDLER(ViewMsg_DragSourceEndedOrMoved, OnDragSourceEndedOrMoved)

#046 IPC_MESSAGE_HANDLER(ViewMsg_DragSourceSystemDragEnded,

#047 OnDragSourceSystemDragEnded)

#048 IPC_MESSAGE_HANDLER(ViewMsg_SetInitialFocus, OnSetInitialFocus)

#049 IPC_MESSAGE_HANDLER(ViewMsg_FindReplyACK, OnFindReplyAck)

#050 IPC_MESSAGE_HANDLER(ViewMsg_UpdateTargetURL_ACK, OnUpdateTargetURLAck)

#051 IPC_MESSAGE_HANDLER(ViewMsg_UpdateWebPreferences, OnUpdateWebPreferences)

#052 IPC_MESSAGE_HANDLER(ViewMsg_SetAltErrorPageURL, OnSetAltErrorPageURL)

#053 IPC_MESSAGE_HANDLER(ViewMsg_InstallMissingPlugin, OnInstallMissingPlugin)

#054 IPC_MESSAGE_HANDLER(ViewMsg_RunFileChooserResponse, OnFileChooserResponse)

#055 IPC_MESSAGE_HANDLER(ViewMsg_EnableViewSourceMode, OnEnableViewSourceMode)

#056 IPC_MESSAGE_HANDLER(ViewMsg_UpdateBackForwardListCount,

#057 OnUpdateBackForwardListCount)

#058 IPC_MESSAGE_HANDLER(ViewMsg_GetAllSavableResourceLinksForCurrentPage,

#059 OnGetAllSavableResourceLinksForCurrentPage)

#060 IPC_MESSAGE_HANDLER(ViewMsg_GetSerializedHtmlDataForCurrentPageWithLocalLinks,

#061 OnGetSerializedHtmlDataForCurrentPageWithLocalLinks)

#062 IPC_MESSAGE_HANDLER(ViewMsg_GetApplicationInfo, OnGetApplicationInfo)

#063 IPC_MESSAGE_HANDLER(ViewMsg_ShouldClose, OnMsgShouldClose)

#064 IPC_MESSAGE_HANDLER(ViewMsg_ClosePage, OnClosePage)

#065 IPC_MESSAGE_HANDLER(ViewMsg_ThemeChanged, OnThemeChanged)

#066 #ifdef CHROME_PERSONALIZATION

#067 IPC_MESSAGE_HANDLER(ViewMsg_PersonalizationEvent, OnPersonalizationEvent)

#068 #endif

#069 IPC_MESSAGE_HANDLER(ViewMsg_HandleMessageFromExternalHost,

#070 OnMessageFromExternalHost)

这里对于没有处理的消息进行提示。

#071 // Have the super handle all other messages.

#072 IPC_MESSAGE_UNHANDLED(RenderWidget::OnMessageReceived(message))

#073 IPC_END_MESSAGE_MAP()

#074 }

从上面这个函数可以看到，它的消息处理是非常多的，下面来分析一个浏览网络连接的消息，它就是ViewMsg_Navigate，可以看到这个消息后面响应函数是OnNavigate，也就是说，当你输入网络地址之后按回车，就会通过上说过的IPC机制把消息发送到这里，接着来看这个函数OnNavigate的代码，如下：

#001 void RenderView::OnNavigate(const ViewMsg_Navigate_Params& params) {

判断窗口是否关闭，如果关闭就不用去打开连接地址了。

#002 if (!webview())

#003 return;

#004

处理一些about的连接处理，比如about:crash。

#005 AboutHandler::MaybeHandle(params.url);

#006

保存是否重新加载网页。

#007 bool is_reload = params.reload;

#008

获取WEB的显示框架。

#009 WebFrame* main_frame = webview()->GetMainFrame();

判断当是重新加载时，而当前又不是历史网页的情况。

#010 if (is_reload && !main_frame->HasCurrentState()) {

#011 // We cannot reload if we do not have any history state. This happens, for

#012 // example, when recovering from a crash. Our workaround here is a bit of

#013 // a hack since it means that reload after a crashed tab does not cause an

#014 // end-to-end cache validation.

#015 is_reload = false;

#016 }

#017

下面设置缓冲策略。

#018 WebRequestCachePolicy cache_policy;

#019 if (is_reload) {

#020 cache_policy = WebRequestReloadIgnoringCacheData;

#021 } else if (params.page_id != -1 || main_frame->GetInViewSourceMode()) {

#022 cache_policy = WebRequestReturnCacheDataElseLoad;

#023 } else {

#024 cache_policy = WebRequestUseProtocolCachePolicy;

#025 }

#026

下面创建一个下载请求，并把相关参数设置到请求里面。

#027 scoped_ptr<WebRequest> request(WebRequest::Create(params.url));

#028 request->SetCachePolicy(cache_policy);

#029 request->SetExtraData(new RenderViewExtraRequestData(

#030 params.page_id, params.transition, params.url));

#031

设置WEBKIT的请求状态。

#032 // If we are reloading, then WebKit will use the state of the current page.

#033 // Otherwise, we give it the state to navigate to.

#034 if (!is_reload)

#035 request->SetHistoryState(params.state);

#036

让主WEB显示框架去下载请求显示。

#037 main_frame->LoadRequest(request.get());

#038 }

分析这个函数，就可以知道处理浏览消息的过程，下一次来分析WebFrame里的接口函数LoadRequest处理过程，到底它是怎么样处理javascript脚本网页下载的呢？