可以实现例如通过应用程序操作google搜索，用户输入要搜索的内容，然后在google中搜索；可以自动点击网页上的按钮等功能

    1. 加入对Microsoft Internet Controls的引用；
    2. 加入对Microsoft HTML Object Library的引用；

（要引入Microsoft.mshtml.dll 地址是C:/Program Files/Microsoft.NET/Primary Interop Assemblies）
    3. 通过mshtml.IHTMLDocument2、SHDocVw.InternetExplorer、SHDocVw.ShellWindowsClass获取当前打开的google搜索页面的IE窗口句柄；
    4. 根据3返回的句柄，获得当前打开的google页面的mshtml.IHTMLDocument2对象；
    5. 根据4返回的IHTMLDocument2对象，获得搜索输入框和提交按钮（可查看google页面源文件，确认输入框和提交按钮的类型和名字）；
    6. 在搜索输入框中输入要搜索的内容，并执行提交按钮的click动作即可进行搜索；

简单来说：

打开ie：

SHDocVw.ShellWindows shellWindows = new SHDocVw.ShellWindowsClass();
object objFlags = 1;
object objTargetFrameName = "";
object objPostData = "";
object objHeaders = "";
SHDocVw.InternetExplorer webBrowser1= (SHDocVw.InternetExplorer)shellWindows.Item(shellWindows.Count-1);
webBrowser1.Navigate(“http://www.google.cn”, ref objFlags, ref objTargetFrameName, ref objPostData, ref objHeaders);

(可以简略点写：object c=null; myWeb.Navigate("http://zhidao.baidu.com/",ref c,ref c,ref c,ref c); )
mshtml.IHTMLDocument2 htmlDoc = webBrowser1.Document as mshtml.IHTMLDocument2;

//...获取WebBroswer中的body代码
mshtml.HTMLDocumentClass doc=(mshtml.HTMLDocumentClass)myWeb.Document;
mshtml.HTMLBody body=(mshtml.HTMLBody)docCC.body;
string html=body.innerHTML.ToString();

//...如果里面有Form，要给里面的text填充信息
mshtml.IHTMLDocument2 doc2=(mshtml.IHTMLDocument2)myWeb.Document;
mshtml.IHTMLElementCollection inputs;
inputs=(mshtml.IHTMLElementCollection)doc2.all.tags("INPUT");
mshtml.IHTMLElement element=(mshtml.IHTMLElement)inputs.item("userName",0);
mshtml.IHTMLInputElement inputElement=(mshtml.IHTMLInputElement)element;
inputElement.value="填充信息";

//...要点击里面的某个按钮
mshtml.IHTMLDocument2 doc2=(mshtml.IHTMLDocument2)myWeb.Document;
mshtml.IHTMLElementCollection inputs;
inputs=(mshtml.IHTMLElementCollection)doc2.all.tags("INPUT");
mshtml.IHTMLElement element=(mshtml.IHTMLElement)inputs.item("SubmitBut",0);
element.click();

1、根据元素ID获取元素的值。

比如要获取<img class="" >这个标签里的src属性的值：

mshtml.IHTMLDocument2 doc2 = (mshtml.IHTMLDocument2)webBrowser1.Document;
mshtml.IHTMLElement img = (mshtml.IHTMLElement)doc2.all.item("regimg", 0);

string imgUrl = (string)img.getAttribute("src");

2、填写表单，并确定

mshtml.IHTMLElement loginname = (mshtml.IHTMLElement)doc2.all.item("loginname", 0);
    mshtml.IHTMLElement loginPW = (mshtml.IHTMLElement)doc2.all.item("password", 0);
    mshtml.IHTMLElement loginBT = (mshtml.IHTMLElement)doc2.all.item("formsubmit", 0);
    mshtml.IHTMLElement loginYZ = (mshtml.IHTMLElement)doc2.all.item("regcode", 0);
    loginname.setAttribute("value", tbLoginName.Text);
    loginPW.setAttribute("value", tbLoginPassWord.Password);
    loginYZ.setAttribute("value", tbYZ.Text);
    loginBT.click();

3、获取源码

textBox1.Text = doc2.body.innerHTML;

4、执行JS

mshtml.IHTMLWindow2 win = (mshtml.IHTMLWindow2)doc2.parentWindow;
win.execScript("changeRegImg()", "javascript");//使用JS

5、禁止JS，WPF下目前发现唯一适用的一种方法：

public void HideScriptErrors(WebBrowser wb, bool Hide)
   {

    FieldInfo fiComWebBrowser = typeof(WebBrowser).GetField("_axIWebBrowser2", BindingFlags.Instance | BindingFlags.NonPublic);

    if (fiComWebBrowser == null) return;

    object objComWebBrowser = fiComWebBrowser.GetValue(wb);

    if (objComWebBrowser == null) return;

    objComWebBrowser.GetType().InvokeMember(

    "Silent", BindingFlags.SetProperty, null, objComWebBrowser, new object[] { Hide });

   }

   void webBrowser1_Navigated(object sender, NavigationEventArgs e)
   {

    HideScriptErrors(webBrowser1,

    true);

   }

下面是另外一遍博客里写的比较好的

#region Search    
        public static void Search(string searchText)   
        {   
            SHDocVw.InternetExplorer ieWnd = GetIEWndOfGoogle();   
            mshtml.IHTMLDocument2 ieDoc = GetIEDocOfGoogle(ref ieWnd);   
  
            System.Diagnostics.Trace.Assert(ieDoc != null);   
            SearchTextInGoogle(ieDoc, searchText);   
  
            //activate ie window    
            SetForegroundWindow(ieWnd.HWND);               
        }   
        #endregion   
 
        #region get ie window of google page    
        public static SHDocVw.InternetExplorer GetIEWndOfGoogle()   
        {   
            mshtml.IHTMLDocument2 ieDoc;   
            SHDocVw.InternetExplorer ieWnd = null;   
            SHDocVw.ShellWindowsClass shellWindows = new SHDocVw.ShellWindowsClass();   
  
            foreach (SHDocVw.InternetExplorer ie in shellWindows)   
            {   
                //if it is ie window    
                if (ie.FullName.ToUpper().IndexOf("IEXPLORE.EXE") > 0)   
                {   
                    //get the document displayed    
                    ieDoc = (mshtml.IHTMLDocument2)ie.Document;   
                    if (ieDoc.title.ToUpper().IndexOf("GOOGLE") >= 0)   
                    {   
                        ieWnd = ie;   
                        break;   
                    }   
                }   
            }   
               
            shellWindows = null;   
  
            return ieWnd;   
        }   
        #endregion   
 
        #region get ie document of google page    
        public static mshtml.IHTMLDocument2 GetIEDocOfGoogle(ref SHDocVw.InternetExplorer ieWnd)   
        {   
            object missing = null;   
            mshtml.IHTMLDocument2 ieDoc;   
  
            if (ieWnd == null)   
            {   
                ieWnd = new SHDocVw.InternetExplorer();   
                ieWnd.Visible = true;   
                ieWnd.Navigate("http://www.google.com", ref missing, ref missing, ref missing, ref missing);   
  
                //wait for loading completed, or using DocumentComplete Event    
                while (ieWnd.StatusText.IndexOf("完成") == -1)   
                    Application.DoEvents();   
            }   
  
            ieDoc = (mshtml.IHTMLDocument2)ieWnd.Document;   
            return ieDoc;   
        }   
        #endregion

#region Search the given text in google    
        ///// <summary>    
        /// search the given text in google home page    
        /// we can see the source file of google home page to confirm the elements we need    
        /// the html file of google home page is as follows    
        ///     
        /// <table cellpadding=0 cellspacing=0>    
        ///     <tr valign=top>    
        ///         <td width=25%> </td>    
        ///         <td align=center nowrap>    
        ///             <input name=hl type=hidden value=zh-CN>    
        ///             <input autocomplete="off" maxlength=2048 name=q size=55 title="Google 搜索" value="">    
        ///             <br>    
        ///             <input name=btnG type=submit value="Google 搜索">    
        ///             <input name=btnI type=submit value=" 手气不错 ">    
        ///         </td>    
        ///         ...    
        ///// </summary>            
        public static void SearchTextInGoogle(mshtml.IHTMLDocument2 ieDoc, string searchText)   
        {   
            mshtml.HTMLInputElementClass input;   
  
            //set the text to be searched    
            foreach (mshtml.IHTMLElement ieElement in ieDoc.all)   
            {   
                //if its tag is input and name is q(question)    
                if (ieElement.tagName.ToUpper().Equals("INPUT"))   
                {   
                    input = ((mshtml.HTMLInputElementClass)ieElement);   
                    if (input.name == "q")   
                    {   
                        input.value = searchText;   
                        break;   
                    }   
                }   
            }   
  
            //click the submit button to search    
            foreach (mshtml.IHTMLElement ieElement in ieDoc.all)   
            {   
                //if its tag is input    
                if (ieElement.tagName.ToUpper().Equals("INPUT"))   
                {   
                    input = (mshtml.HTMLInputElementClass)ieElement;   
                    if (input.name == "btnG")   
                    {   
                        input.click();   
                        break;   
                    }   
                }   
            }   
        }   
        #endregion