查找了很多資料，才解決了這個問題，借鑒前輩的代碼思路
需要新建一個輔助類
主要代碼（輔助類代碼）：
// This is the COM IServiceProvider interface, not System.IServiceProvider .Net interface!
[ComImport(), ComVisible(true), Guid("6D5140C1-7436-11CE-8034-00AA006009FA"),
InterfaceTypeAttribute(ComInterfaceType.InterfaceIsIUnknown)]
public interface IServiceProvider
{
[return: MarshalAs(UnmanagedType.I4)]
[PreserveSig]
int QueryService(ref Guid guidService, ref Guid riid, [MarshalAs(UnmanagedType.Interface)] out object ppvObject);
}
public enum OLECMDF
{
OLECMDF_DEFHIDEONCTXTMENU = 0x20,
OLECMDF_ENABLED = 2,
OLECMDF_INVISIBLE = 0x10,
OLECMDF_LATCHED = 4,
OLECMDF_NINCHED = 8,
OLECMDF_SUPPORTED = 1
}
public enum OLECMDID
{
OLECMDID_PAGESETUP = 8,
OLECMDID_PRINT = 6,
OLECMDID_PRINTPREVIEW = 7,
OLECMDID_PROPERTIES = 10,
OLECMDID_SAVEAS = 4
}
public enum OLECMDEXECOPT
{
OLECMDEXECOPT_DODEFAULT,
OLECMDEXECOPT_PROMPTUSER,
OLECMDEXECOPT_DONTPROMPTUSER,
OLECMDEXECOPT_SHOWHELP
}
[ComImport, Guid("D30C1661-CDAF-11d0-8A3E-00C04FC9E26E"), TypeLibType(TypeLibTypeFlags.FOleAutomation | TypeLibTypeFlags.FDual | TypeLibTypeFlags.FHidden)]
public interface IWebBrowser2
{
[DispId(100)]
void GoBack();
[DispId(0x65)]
void GoForward();
[DispId(0x66)]
void GoHome();
[DispId(0x67)]
void GoSearch();
[DispId(0x68)]
void Navigate([In] string Url, [In] ref object flags, [In] ref object targetFrameName, [In] ref object postData, [In] ref object headers);
[DispId(-550)]
void Refresh();
[DispId(0x69)]
void Refresh2([In] ref object level);
[DispId(0x6a)]
void Stop();
[DispId(200)]
object Application { [return: MarshalAs(UnmanagedType.IDispatch)] get; }
[DispId(0xc9)]
object Parent { [return: MarshalAs(UnmanagedType.IDispatch)] get; }
[DispId(0xca)]
object Container { [return: MarshalAs(UnmanagedType.IDispatch)] get; }
[DispId(0xcb)]
object Document { [return: MarshalAs(UnmanagedType.IDispatch)] get; }
[DispId(0xcc)]
bool TopLevelContainer { get; }
[DispId(0xcd)]
string Type { get; }
[DispId(0xce)]
int Left { get; set; }
[DispId(0xcf)]
int Top { get; set; }
[DispId(0xd0)]
int Width { get; set; }
[DispId(0xd1)]
int Height { get; set; }
[DispId(210)]
string LocationName { get; }
[DispId(0xd3)]
string LocationURL { get; }
[DispId(0xd4)]
bool Busy { get; }
[DispId(300)]
void Quit();
[DispId(0x12d)]
void ClientToWindow(out int pcx, out int pcy);
[DispId(0x12e)]
void PutProperty([In] string property, [In] object vtValue);
[DispId(0x12f)]
object GetProperty([In] string property);
[DispId(0)]
string Name { get; }
[DispId(-515)]
int HWND { get; }
[DispId(400)]
string FullName { get; }
[DispId(0x191)]
string Path { get; }
[DispId(0x192)]
bool Visible { get; set; }
[DispId(0x193)]
bool StatusBar { get; set; }
[DispId(0x194)]
string StatusText { get; set; }
[DispId(0x195)]
int ToolBar { get; set; }
[DispId(0x196)]
bool MenuBar { get; set; }
[DispId(0x197)]
bool FullScreen { get; set; }
[DispId(500)]
void Navigate2([In] ref object URL, [In] ref object flags, [In] ref object targetFrameName, [In] ref object postData, [In] ref object headers);
[DispId(0x1f5)]
OLECMDF QueryStatusWB([In] OLECMDID cmdID);
[DispId(0x1f6)]
void ExecWB([In] OLECMDID cmdID, [In] OLECMDEXECOPT cmdexecopt, ref object pvaIn, IntPtr pvaOut);
[DispId(0x1f7)]
void ShowBrowserBar([In] ref object pvaClsid, [In] ref object pvarShow, [In] ref object pvarSize);
[DispId(-525)]
WebBrowserReadyState ReadyState { get; }
[DispId(550)]
bool Offline { get; set; }
[DispId(0x227)]
bool Silent { get; set; }
[DispId(0x228)]
bool RegisterAsBrowser { get; set; }
[DispId(0x229)]
bool RegisterAsDropTarget { get; set; }
[DispId(0x22a)]
bool TheaterMode { get; set; }
[DispId(0x22b)]
bool AddressBar { get; set; }
[DispId(0x22c)]
bool Resizable { get; set; }
}
class CorssDomainHelper
{
private static Guid IID_IWebBrowserApp = new Guid("0002DF05-0000-0000-C000-000000000046");
private static Guid IID_IWebBrowser2 = new Guid("D30C1661-CDAF-11D0-8A3E-00C04FC9E26E");
// Utility for IE cross domain access
// Returns null in case of failure.
public static IHTMLDocument3 GetDocumentFromWindow(IHTMLWindow2 htmlWindow)
{
if (htmlWindow == null)
{
return null;
}
// First try the usual way to get the document.
try
{
IHTMLDocument2 doc = htmlWindow.document;
return (IHTMLDocument3)doc;
}
catch (COMException comEx)
{
// I think COMException won't be ever fired but just to be sure ...
}
catch (UnauthorizedAccessException)
{
}
catch (Exception ex)
{
return null;
}
// At this point the error was E_ACCESSDENIED because the frame contains a document from another domain.
// IE tries to prevent a cross frame scripting security issue.
try
{
// Convert IHTMLWindow2 to IWebBrowser2 using IServiceProvider.
IServiceProvider sp = (IServiceProvider)htmlWindow;
// Use IServiceProvider.QueryService to get IWebBrowser2 object.
Object brws = null;
sp.QueryService(ref IID_IWebBrowserApp, ref IID_IWebBrowser2, out brws);
// Get the document from IWebBrowser2.
IWebBrowser2 browser = (IWebBrowser2)(brws);
return (IHTMLDocument3)browser.Document;
}
catch (Exception ex)
{
Console.WriteLine(ex);
}
return null;
}
}
實現頁代碼：
for (int i = 0; i < webBrowser1.Document.Window.Frames.Count; i++)
{
IHTMLDocument3 baiduDoc = CorssDomainHelper.GetDocumentFromWindow(webBrowser1.Document.Window.Frames[i].DomWindow
as IHTMLWindow2);
if (baiduDoc != null && baiduDoc.documentElement != null && baiduDoc.documentElement.document != null)
{
IHTMLElementCollection linkss = ((HTMLDocument)(baiduDoc.documentElement.document)).links;
foreach (mshtml.IHTMLElement element in linkss)
{
IHTMLElement userid = baiduDoc.getElementById("u");
IHTMLElement userpwd = baiduDoc.getElementById("p");
IHTMLElement btn = baiduDoc.getElementById("login_button");
if (userid == null || userpwd == null || btn == null)
{
return;
}
userid.setAttribute("value", "賬號");
userpwd.setAttribute("value", "密碼");
btn.click();
}
}
}