C#开发中WebBrowser控件的跨域问题使用实例

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我们在做web测试时，经常会使用WebBrowser来进行一些自动化的任务。而有些网页上面会用IFrame去嵌套别的页面，这些页面可能不是在相同域名下的，这时就会出现跨域问题，无法直接在WebBrowser中获取到IFrame中的元素。下面来做个试验，自己写个页面嵌套一个百度的首页，然后在我们自己的页面上输入要查询的词，最后在百度上自动完成搜索。

<!DOCTYPE html>

<html lang="en" xmlns="http://www.w3.org/1999/xhtml">
<head>
    <meta charset="utf-8" />
    <title></title>
</head>
<body>
    <iframe id="baidu" style="float:left;" width="500" height="500" src="http://www.baidu.com"></iframe>
    <div>
        测试值：<input id="search" type="text" />
    </div>
</body>
</html>

下面再建一个简单的WinForm工程测试一下，界面如下：

下面就是WebBrowser的测试代码：

using System;
using System.Windows.Forms;

namespace WebBrowsertest
{
    public partial class Form1 : Form
    {

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            this.webBrowser1.Navigate(this.textBox1.Text);
        }

        private void button2_Click(object sender, EventArgs e)
        {
            var doc = this.webBrowser1.Document;
            var frames = doc.Window.Frames;
            String testValue = doc.GetElementById("search").GetAttribute("value");
            frames[0].Document.GetElementById("kw").SetAttribute("value", testValue);
            frames[0].Document.GetElementById("su").InvokeMember("click");

        }

    }
}

我们运行我们的测试程序后，加载之前我们自己写的页面后，在自己的页面上输入我们要查询的词，点击测试按钮，就会看到程序报未处理 UnauthorizedAccessException错误：

下面来编写一个Helper类来解决这个问题，主要原理大致就是利用IWebBrowser2这个接口来获取Ifream中的Dom，IWebBrowser2中的document可以转换为IHtmlDocument1，IHtmlDocument2，IHtmlDocument3。

using System;
using System.Runtime.InteroPServices;
using System.Windows.Forms;
using mshtml;

namespace WebBrowserTest
{
    // 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;
        }
    }
}

最后将我们的运行代码改为如下形式，调用Helper类中的GetDocumentFromWindow方法：

using System;
using System.Windows.Forms;
using mshtml;

namespace WebBrowserTest
{
    public partial class Form1 : Form
    {

        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            this.webBrowser1.Navigate(this.textBox1.Text);
        }

        private void button2_Click(object sender, EventArgs e)
        {
            var doc = this.webBrowser1.Document;
            var frames = doc.Window.Frames;
            String testValue = doc.GetElementById("search").GetAttribute("value");
            IHTMLDocument3 baiduDoc = CorssDomainHelper.GetDocumentFromWindow(frames[0].DomWindow as IHTMLWindow2);
            baiduDoc.getElementById("kw").setAttribute("value", testValue);
            baiduDoc.getElementById("su").click();

        }
    }
}