WEB工具类，很强很大

这个类主要是针对WEB请求响应的一个工具类，它封装了WEB请求出来的很多方法，功能非常强大

using System;
using System.Text;
using System.Net;
using System.Net.Sockets;
using System.IO;
using System.Security;
using System.Collections.Specialized;
using System.Runtime.InteropServices;
using System.Diagnostics;
using System.Net.Cache;
using System.Web;
using System.Reflection;
using System.Web.Compilation;
using System.CodeDom.Compiler;
using System.Configuration;
using mshtml;
using System.DirectoryServices;

namespace CSharpRecipes
{
    public class Web
    {
        private static string GetWebAppPath()
        {
            // get the path for this app
            string path = Path.GetDirectoryName(Process.GetCurrentProcess().MainModule.FileName);

            #region Code to make it work in debug
            // figure out where the web code is, should be in an adjacent directory
            // to the console app code
            string cscbWebPath = path;
            int index = -1;
            // keep backing up directories till we find it
            while (!Directory.Exists(cscbWebPath + @"\CSCBWeb"))
            {
                index = cscbWebPath.LastIndexOf('\\');
                if (index == -1)
                {
                    cscbWebPath = "";
                    break;
                }
                cscbWebPath = cscbWebPath.Substring(0, index);
            }
            #endregion

            // make sure we have a web path
            if (cscbWebPath.Length > 0)
            {
                // append webdir name
                cscbWebPath += @"\CSCBWeb";
            }
            return cscbWebPath;
        }


        #region 14.1 Converting an IP Address to a Host Name
        public static void ConvertIPToHostName()
        {
            // use the dns class to resolve from the address to the iphostentry
            try
            {
                IPHostEntry iphost = Dns.GetHostEntry("90.0.0.47");
                // HostName property holds the host name
                string hostName = iphost.HostName;
                // print out name
                Console.WriteLine(hostName);
            }
            catch (Exception e)
            {
                Console.WriteLine(e);
            }
        }
        #endregion

        #region 14.2 Converting a Host Name to an IP Address
        public static void ConvertingHostNameToIP()
        {
            // writes "IP Address: 208.201.239.37;IP Address: 208.201.239.36;"
            Console.WriteLine(HostName2IP("www.oreilly.com"));
        }

        public static string HostName2IP(string hostname)
        {
            // resolve the hostname into an iphost entry using the dns class
            IPHostEntry iphost = System.Net.Dns.GetHostEntry(hostname);
            // get all of the possible IP addresses for this hostname
            IPAddress[] addresses = iphost.AddressList;
            // make a text representation of the list
            StringBuilder addressList = new StringBuilder();
            // get each ip address
            foreach (IPAddress address in addresses)
            {
                // append it to the list
                addressList.AppendFormat("IP Address: {0};", address.ToString());
            }
            return addressList.ToString();
        }

        #endregion

        #region 14.3 Parsing a URI
        public static void ParsingURI()
        {
            Web.ParseUri("http://user:password@localhost:8080/www.abc.com/home%20page.htm?item=1233#stuff");
        }
        public static void ParseUri(string uriString)
        {
            try
            {
                // just use one of the constructors for the System.Net.Uri class
                // this will parse it for us.
                Uri uri = new Uri(uriString);
                // Look at the information we can get at now
                StringBuilder uriParts = new StringBuilder();
                uriParts.AppendFormat("AbsoluteURI: {0}{1}",
                                    uri.AbsoluteUri,Environment.NewLine);
                uriParts.AppendFormat("AbsolutePath: {0}{1}",
                                    uri.AbsolutePath,Environment.NewLine);
                uriParts.AppendFormat("Scheme: {0}{1}",
                                    uri.Scheme,Environment.NewLine);
                uriParts.AppendFormat("UserInfo: {0}{1}",
                                    uri.UserInfo,Environment.NewLine);
                uriParts.AppendFormat("Authority: {0}{1}",
                                    uri.Authority,Environment.NewLine);
                uriParts.AppendFormat("DnsSafeHost: {0}{1}",
                                    uri.DnsSafeHost,Environment.NewLine);
                uriParts.AppendFormat("Host: {0}{1}",
                                    uri.Host,Environment.NewLine);
                uriParts.AppendFormat("HostNameType: {0}{1}",
                                    uri.HostNameType.ToString(),Environment.NewLine);
                uriParts.AppendFormat("Port: {0}{1}",uri.Port,Environment.NewLine);
                uriParts.AppendFormat("Path: {0}{1}",uri.LocalPath,Environment.NewLine);
                uriParts.AppendFormat("QueryString: {0}{1}",uri.Query,Environment.NewLine);
                uriParts.AppendFormat("Path and QueryString: {0}{1}",
                                    uri.PathAndQuery,Environment.NewLine);
                uriParts.AppendFormat("Fragment: {0}{1}",uri.Fragment,Environment.NewLine);
                uriParts.AppendFormat("Original String: {0}{1}",
                                    uri.OriginalString,Environment.NewLine);
                uriParts.AppendFormat("Segments: {0}",Environment.NewLine);
                for (int i = 0; i < uri.Segments.Length; i++)
                    uriParts.AppendFormat("    Segment {0}:{1}{2}",
                                    i, uri.Segments[i], Environment.NewLine);


                // GetComponents can be used to get commonly used combinations
                // of Uri information
                uriParts.AppendFormat("GetComponents for specialized combinations: {0}",
                                    Environment.NewLine);
                uriParts.AppendFormat("Host and Port (unescaped): {0}{1}",
                                    uri.GetComponents(UriComponents.HostAndPort,
                                    UriFormat.Unescaped),Environment.NewLine);
                uriParts.AppendFormat("HttpRequestUrl (unescaped): {0}{1}",
                                    uri.GetComponents(UriComponents.HttpRequestUrl, 
                                    UriFormat.Unescaped),Environment.NewLine);
                uriParts.AppendFormat("HttpRequestUrl (escaped): {0}{1}",
                                    uri.GetComponents(UriComponents.HttpRequestUrl, 
                                    UriFormat.UriEscaped),Environment.NewLine);
                uriParts.AppendFormat("HttpRequestUrl (safeunescaped): {0}{1}",
                                    uri.GetComponents(UriComponents.HttpRequestUrl, 
                                    UriFormat.SafeUnescaped),Environment.NewLine);
                uriParts.AppendFormat("Scheme And Server (unescaped): {0}{1}",
                                    uri.GetComponents(UriComponents.SchemeAndServer, 
                                    UriFormat.Unescaped),Environment.NewLine);
                uriParts.AppendFormat("SerializationInfo String (unescaped): {0}{1}",
                                    uri.GetComponents(UriComponents.SerializationInfoString, 
                                    UriFormat.Unescaped),Environment.NewLine);
                uriParts.AppendFormat("StrongAuthority (unescaped): {0}{1}",
                                    uri.GetComponents(UriComponents.StrongAuthority, 
                                    UriFormat.Unescaped),Environment.NewLine);
                uriParts.AppendFormat("StrongPort (unescaped): {0}{1}",
                                    uri.GetComponents(UriComponents.StrongPort, 
                                    UriFormat.Unescaped),Environment.NewLine);

                // write out our summary
                Console.WriteLine(uriParts.ToString());
            }
            catch (ArgumentNullException e)
            {
                // uriString is a null reference (Nothing in Visual Basic). 
                Console.WriteLine("URI string object is a null reference: {0}", e);
            }
            catch (UriFormatException e)
            {
                Console.WriteLine("URI formatting error: {0}", e);
            }
        }

        #endregion

        #region 14.4 Forming an Absolute URI
        public static void FormingAbsoluteURI()
        {
            Uri myUri = CreateAndVerifyAbsoluteUri("http://www.oreilly.com",
                "hello%20world.htm");

            // displays http://www.oreilly.com/hello world.htm
            Console.WriteLine(myUri.AbsoluteUri);
        }

        public static Uri CreateAndVerifyAbsoluteUri(string uriBaseString, string uriRelativeString)
        {
            try
            {
                // make the base uri
                Uri baseUri = new Uri(uriBaseString,UriKind.Absolute);
                // Make the relative Uri
                Uri relativeUri = new Uri(uriRelativeString, UriKind.Relative);
                // create the full uri by combining the base and relative 
                Uri absoluteUri = new Uri(baseUri, relativeUri);

                // verify we did make an absolute uri
                if(absoluteUri.IsAbsoluteUri==false)
                    throw new UriFormatException(
                        "Could not form absolute Uri from " + 
                        baseUri.OriginalString + " and " + 
                        relativeUri.OriginalString);

                // make sure our original base Uri is a base uri for the new
                // absolute Uri
                if(baseUri.IsBaseOf(absoluteUri)==false)
                    throw new UriFormatException(
                        "Base Uri was invalid for newly formed Absolute Uri: " + 
                        baseUri.OriginalString + " and " + 
                        absoluteUri.OriginalString);

                // get the relative uri from the difference between the base 
                // and the absolute uris
                Uri relCheckUri = baseUri.MakeRelativeUri(absoluteUri);
                // this new relative uri should equal our previous uri
                if(relCheckUri != relativeUri)
                    throw new UriFormatException(
                        "Could not make equivalent relative Uri from new Absolute Uri: " +
                        relCheckUri.OriginalString + " and " +
                        absoluteUri.OriginalString);

                Uri newAbsoluteUri = new Uri(baseUri, relCheckUri);
                // check that the new and the original match
                if(Uri.Compare(absoluteUri, newAbsoluteUri, 
                    UriComponents.AbsoluteUri, UriFormat.Unescaped, 
                    StringComparison.InvariantCulture) != 0)
                {
                    throw new UriFormatException(
                        "New Absolute Uri did not equal originally formed Absolute Uri: " + 
                        baseUri.OriginalString + " and " + 
                        absoluteUri.OriginalString);
                }

                // it's ok, send it
                return absoluteUri;
            }
            catch (ArgumentNullException e)
            {
                // uriString is a null reference (Nothing in Visual Basic). 
                Console.WriteLine("URI string object is a null reference: {0}", e);
            }
            catch (UriFormatException e)
            {
                Console.WriteLine("URI formatting error: {0}", e);

            }
            return null;
        }

        #endregion

        #region 14.5 Handling Web Server Errors
        public enum ResponseCategories
        {
            Unknown = 0,        // unknown code  ( < 100 or > 599)
            Informational = 1,  // informational codes (100 <= 199)
            Success = 2,        // success codes (200 <= 299)
            Redirected = 3,     // redirection code (300 <= 399)
            ClientError = 4,    // client error code (400 <= 499)
            ServerError = 5     // server error code (500 <= 599)
        }

        public static void HandlingWebServerErrors()
        {
            HttpWebRequest httpRequest = null;
            // get a URI object
            Uri uri = new Uri("http://localhost");
            // create the initial request
            httpRequest = (HttpWebRequest)WebRequest.Create(uri);
            HttpWebResponse httpResponse = null;
            try
            {
                httpResponse = (HttpWebResponse)httpRequest.GetResponse();
            }
            catch (WebException we)
            {
                Console.WriteLine(we.ToString());
                return;
            }
            switch (VerifyResponse(httpResponse))
            {
                case ResponseCategories.Unknown:
                    Console.WriteLine("Unknown");
                    break;
                case ResponseCategories.Informational:
                    Console.WriteLine("Informational");
                    break;
                case ResponseCategories.Success:
                    Console.WriteLine("Success");
                    break;
                case ResponseCategories.Redirected:
                    Console.WriteLine("Redirected");
                    break;
                case ResponseCategories.ClientError:
                    Console.WriteLine("ClientError");
                    break;
                case ResponseCategories.ServerError:
                    Console.WriteLine("ServerError");
                    break;

            }
        }

        public static ResponseCategories VerifyResponse(HttpWebResponse httpResponse)
        {
            // Just in case there are more success codes defined in the future
            // by HttpStatusCode, we will check here for the "success" ranges
            // instead of using the HttpStatusCode enum as it overloads some
            // values
            int statusCode = (int)httpResponse.StatusCode;
            if ((statusCode >= 100) && (statusCode <= 199))
            {
                return ResponseCategories.Informational;
            }
            else if ((statusCode >= 200) && (statusCode <= 299))
            {
                return ResponseCategories.Success;
            }
            else if ((statusCode >= 300) && (statusCode <= 399))
            {
                return ResponseCategories.Redirected;
            }
            else if ((statusCode >= 400) && (statusCode <= 499))
            {
                return ResponseCategories.ClientError;
            }
            else if ((statusCode >= 500) && (statusCode <= 599))
            {
                return ResponseCategories.ServerError;
            }
            return ResponseCategories.Unknown;
        }

        #endregion

        #region 14.6 Communicating with a Web Server
        public static void CommunicatingWithWebServer()
        {
            HttpWebRequest request =
                GenerateHttpWebRequest("http://localhost/mysite/index.aspx");

            using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
            {
                // This next line uses VerifyResponse from Recipe 14.5
                if (VerifyResponse(response) == ResponseCategories.Success)
                {
                    Console.WriteLine("Request succeeded");
                }
            }
        }

        // GET overload
        public static HttpWebRequest GenerateHttpWebRequest(string uriString)
        {
            // get a URI object
            Uri uri = new Uri(uriString);
            // create the initial request
            HttpWebRequest httpRequest = (HttpWebRequest)WebRequest.Create(uri);
            // return the request
            return httpRequest;
        }

        // POST overload
        public static HttpWebRequest GenerateHttpWebRequest(string uriString,
            string postData,
            string contentType)
        {
            // get a URI object
            Uri uri = new Uri(uriString);
            // create the initial request
            HttpWebRequest httpRequest = (HttpWebRequest)WebRequest.Create(uri);

            // Get the bytes for the request, should be pre-escaped
            byte[] bytes = Encoding.UTF8.GetBytes(postData);

            // Set the content type of the data being posted.
            httpRequest.ContentType = contentType;
                //"application/x-www-form-urlencoded"; for forms

            // Set the content length of the string being posted.
            httpRequest.ContentLength = postData.Length;

            // Get the request stream and write the post data in
            using (Stream requestStream = httpRequest.GetRequestStream())
            {
                requestStream.Write(bytes, 0, bytes.Length);
            }
            // return the request
            return httpRequest;
        }

        #endregion

        #region 14.7 Going Through a Proxy
        public static void GoingThroughProxy()
        {
            HttpWebRequest request =
                GenerateHttpWebRequest("http://internethost/mysite/index.aspx");

            // add the proxy info
            AddProxyInfoToRequest(request, "http://webproxy:80", "user", "pwd", "domain");

            // or set it up to go through the same proxy for all responses
            Uri proxyURI = new Uri("http://webproxy:80");

            // in 1.1 you used to do this:
            //GlobalProxySelection.Select = new WebProxy(proxyURI);
            // Now in 2.0 you do this:
            WebRequest.DefaultWebProxy = new WebProxy(proxyURI);
        }

        public static HttpWebRequest AddProxyInfoToRequest(HttpWebRequest httpRequest,
            string proxyUri,
            string proxyID,
            string proxyPwd,
            string proxyDomain)
        {
            if (httpRequest != null)
            {
                // create the proxy object
                WebProxy proxyInfo = new WebProxy();
                // add the address of the proxy server to use
                proxyInfo.Address = new Uri(proxyUri);
                // tell it to bypass the proxy server for local addresses
                proxyInfo.BypassProxyOnLocal = true;
                // add any credential information to present to the proxy server
                proxyInfo.Credentials = new NetworkCredential(proxyID,
                    proxyPwd,
                    proxyDomain);
                // assign the proxy information to the request
                httpRequest.Proxy = proxyInfo;
            }
            // return the request
            return httpRequest;
        }

        #endregion

        #region 14.8 Obtaining the HTML from a URL
        public static void ObtainingHTMLFromURL()
        {
            try
            {
                string html = GetHtmlFromUrl("http://www.oreilly.com");
            }
            catch (WebException e)
            {
                Console.WriteLine(e);
            }
        }

        public static string GetHtmlFromUrl(string url)
        {
            if (string.IsNullOrEmpty(url))
                throw new ArgumentNullException("url","Parameter is null or empty");

            string html = "";
            HttpWebRequest request = GenerateHttpWebRequest(url);
            using(HttpWebResponse response = (HttpWebResponse)request.GetResponse())
            {
                if (VerifyResponse(response) == ResponseCategories.Success)
                {
                    // get the response stream.
                    Stream responseStream = response.GetResponseStream();
                    // use a stream reader that understands UTF8
                    using(StreamReader reader = new StreamReader(responseStream, Encoding.UTF8))
                    {
                        html = reader.ReadToEnd();
                    }
                }
            }
            return html;
        }

        #endregion

        #region "14.9 Using the new web browser control"
        // See the WebBrowser project 
        #endregion 

        #region "14.10 Tying your database code to the cache"
        // See the CSCBWeb project for this code 
        #endregion

        #region "14.11 Caching data with multiple dependencies"
        // See the CSCBWeb project for this code 
        #endregion

        #region "14.12 Pre-building an ASP.NET web site programmatically"
        public class MyClientBuildManagerCallback : ClientBuildManagerCallback
        {
            public MyClientBuildManagerCallback()
                : base()
            {
            }

            public override void ReportCompilerError(CompilerError error)
            {
                string msg = "Report Compiler Error: " + error.ToString();
                Debug.WriteLine(msg);
                Console.WriteLine(msg);
            }

            public override void ReportParseError(ParserError error)
            {
                string msg = "Report Parse Error: " + error.ToString();
                Debug.WriteLine(msg);
                Console.WriteLine(msg);
            }

            public override void ReportProgress(string message)
            {
                string msg = "Report Progress: " + message;
                Debug.WriteLine(msg);
                Console.WriteLine(msg);
            }
        }

        public static void TestBuildASPNETPages()
        {
            try
            {
                // get the path to the web app shipping with this code
                string cscbWebPath = GetWebAppPath();

                // make sure we have a web path
                if(cscbWebPath.Length>0)
                {
                    string appVirtualDir = @"CSCBWeb";
                    string appPhysicalSourceDir = cscbWebPath;
                    // make the target an adjacent directory as it cannot be in the same tree
                    // or the buildmanager screams
                    string appPhysicalTargetDir = Path.GetDirectoryName(cscbWebPath) + @"\BuildCSCB"; 

                    // check flags again in Beta2, more options
                    //AllowPartiallyTrustedCallers   
                    //Clean   
                    //CodeAnalysis   
                    //Default   
                    //DelaySign   
                    //FixedNames   
                    //ForceDebug   
                    //OverwriteTarget   
                    //Updatable 

//                    Report Progress: Building directory '/CSCBWeb/App_Data'.
//Report Progress: Building directory '/CSCBWeb/Role_Database'.
//Report Progress: Building directory '/CSCBWeb'.
//Report Compiler Error: c:\PRJ32\Book_2_0\C#Cookbook2\Code\CSCBWeb\Default.aspx.cs(14,7) : warning CS0105: The using directive for 'System.Configuration' appeared previously in this namespace


//                    Report Progress: Building directory '/CSCBWeb/App_Data'.
//Report Progress: Building directory '/CSCBWeb/Role_Database'.
//Report Progress: Building directory '/CSCBWeb'.

                    PrecompilationFlags flags = PrecompilationFlags.ForceDebug |
                                                PrecompilationFlags.OverwriteTarget;

                    ClientBuildManagerParameter cbmp = new ClientBuildManagerParameter();
                    cbmp.PrecompilationFlags = flags;
                    ClientBuildManager cbm =
                            new ClientBuildManager(appVirtualDir, 
                                                    appPhysicalSourceDir, 
                                                    appPhysicalTargetDir,
                                                    cbmp);
                    MyClientBuildManagerCallback myCallback = new MyClientBuildManagerCallback();
                    cbm.PrecompileApplication(myCallback);
                }
            }
            catch (Exception e)
            {
                Debug.WriteLine(e.ToString());
            }
        }
        #endregion

        #region "14.13 Escaping and Unescaping data for the web"
        public static void TestEscapeUnescape()
        {
            string data = "<H1>My html</H1>";
            Console.WriteLine("Original Data: {0}",data);
            Console.WriteLine();
            // public static string EscapeDataString(string stringToEscape);
            string escapedData = Uri.EscapeDataString(data);
            Console.WriteLine("escaped Data: {0}",escapedData);
            Console.WriteLine();
            // public static string UnescapeDataString(    string stringToUnescape);
            string unescapedData = Uri.UnescapeDataString(escapedData);
            Console.WriteLine("unescaped Data: {0}",data);
            Console.WriteLine();
            string uriString = "http://user:password@localhost:8080/www.abc.com/" + 
                "home page.htm?item=1233;html=<h1>Heading</h1>#stuff";
            Console.WriteLine("Original Uri string: {0}",uriString);
            Console.WriteLine();

            // public static string EscapeUriString(string stringToEscape);
            string escapedUriString = Uri.EscapeUriString(uriString);
            Console.WriteLine("Escaped Uri string: {0}",escapedUriString);
            Console.WriteLine();

            // Why not just use EscapeDataString to escape a Uri?  It's not picky enough
            string escapedUriData = Uri.EscapeDataString(uriString);
            Console.WriteLine("Escaped Uri data: {0}",escapedUriData);
            Console.WriteLine();

            Console.WriteLine(Uri.UnescapeDataString(escapedUriString));
        }
        



        #endregion

        #region "14.14 Bulletproof creating a Uri"
        public class UriBuilderFix : UriBuilder
        {
            public UriBuilderFix() : base()
            {
            }

            public new string Query
            {
                get
                {
                    return base.Query;
                }
                 set
                {
                    if (!string.IsNullOrEmpty(value))
                    {
                        if (value[0] == '?')
                            // trim off the leading ? as the underlying 
                            // UriBuilder class will add one to the 
                            // querystring.  Also prepend ; for additional items
                            base.Query = value.Substring(1);
                        else
                            base.Query = value;
                    }
                    else
                        base.Query = string.Empty;
                }
            }
        }
        
        public static void TestUriBuilder()
        {
            //string uriString = "http://user:password@localhost:8080/www.abc.com/" + 
            //    "home page.htm?item=1233;html=<h1>Heading</h1>#stuff";
            //[scheme]://[user]:[password]@[host/authority]:[port]/[path];[params]?
            //[query string]#[fragment]

            try
            {
                UriBuilderFix ubf = new UriBuilderFix();
                ubf.Scheme = "http";
                ubf.UserName = "user";
                ubf.Password = "password";
                ubf.Host = "localhost";
                ubf.Port = 8080;
                ubf.Path = "www.abc.com/home page.htm";

                //The Query property contains any query information included in the URI. 
                //Query information is separated from the path information by a question mark (?) and continues 
                //to the end of the URI. The query information returned includes the leading question mark.
                //The query information is escaped according to RFC 2396.
                //Setting the Query property to null or to System.String.Empty clears the property.
                //Note:   Do not append a string directly to this property. 
                //Instead retrieve the property value as a string, remove the leading question mark, 
                //append the new query string, and set the property with the combined string.

                // Don't Do This, too many ? marks, one for every append
                ubf.Query = "item=1233";
                ubf.Query += ";html=<h1>heading</h1>";

                ubf.Fragment = "stuff";

                Console.WriteLine("Absolute Composed Uri: " + ubf.Uri.AbsoluteUri); 
                Console.WriteLine("Composed Uri: " + ubf.ToString());

                UriBuilder ub = new UriBuilder();
                ub.Query = "item=1233";
                ub.Query += ";html=<h1>heading</h1>";
                
            }
            catch (Exception e)
            {
                Console.WriteLine("Exception thrown building Uri: " + e.ToString());
            }
        }
        #endregion

        #region "14.15 Inspect and change your web application configuration (System.Web.Configuration)"
        // see the CSCBWeb project for code
        #endregion

        #region "14.16 Working with HTML"
        public static void TestHTMLParser()
        {
            HTMLDocument htmlDoc = new HTMLDocument();
            IHTMLDocument2 iHtmlDoc2 = null;

            string html = 
                "<!DOCTYPE html PUBLIC \"-//W3C//DTD XHTML 1.1//EN\"" +
                "\"http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd\">" +
                "<html xmlns=\"http://www.w3.org/1999/xhtml\" >" + 
                "<head><title>Test Page</title></head>" +
                "<body><form method=\"post\" action=\"Default.aspx\" id=\"form1\">" +
                "<div><input id=\"Text1\" type=\"text\" />" +
                "<input id=\"Checkbox1\" type=\"checkbox\" />" +
                "<input id=\"Radio1\" type=\"radio\" />" +
                "<select id=\"Select1\">" +
                "<option selected=\"selected\"></option></select>" +
                "<input name=\"TextBox1\" type=\"text\" id=\"TextBox1\" />" +
                "</div></form></body></html>";

            // get the IHTMLDocument2 interface
            iHtmlDoc2 = (IHTMLDocument2)htmlDoc;

            // Put the document in design mode so we don't execute scripts
            // while loading
            iHtmlDoc2.designMode = "On";

            // Have to put some HTML in the DOM before using it
            iHtmlDoc2.write(html);

            // close it
            iHtmlDoc2.close();

            //roll over every element in the html
            foreach (IHTMLElement htmlElem in (IHTMLElementCollection)iHtmlDoc2.body.all)
            {
                // Note: every time we do the is and as, it does a COM call to the
                // MSHTML object.  This can be rather expensive so you would want to cache
                // the results elsewhere once you have them, don't just keep calling
                // properties on it as those end up making a round trip as well.
                if (htmlElem is IHTMLAnchorElement)
                {
                    HTMLAnchorElementClass anchor = htmlElem as HTMLAnchorElementClass;
                    if (anchor != null)
                        Console.WriteLine("Anchor element found: " + anchor.href);
                    continue;
                }
                else if (htmlElem is IHTMLFormElement)
                {
                    HTMLFormElementClass form = htmlElem as HTMLFormElementClass;
                    if (form != null)
                        Console.WriteLine("Form element found: " + form.id);
                    continue;
                }
                else if (htmlElem is IHTMLInputElement)
                {
                    HTMLInputElementClass input = htmlElem as HTMLInputElementClass;
                    if (input != null)
                        Console.WriteLine("Input Element found: " + input.name);
                    continue;
                }
                else if (htmlElem is IHTMLTextAreaElement)
                {
                    HTMLTextAreaElementClass text = htmlElem as HTMLTextAreaElementClass;
                    if (text != null)
                        Console.WriteLine("Text Area Element found: " + text.name);
                    continue;
                }

            }

        }
        #endregion

        #region "14.17 Using cached results when working with HTTP for faster performance"
        public static void TestCache()
        {
            // 14.6 has generategetorpostrequest
            string html = "";
            string url = "http://www.oreilly.com";
            // set up the request
            HttpWebRequest request = GenerateHttpWebRequest(url);
            
            // make a cache policy to use cached results if available
            // the default is to Bypass the cache in machine.config.
            RequestCachePolicy rcpCheckCache = 
                new RequestCachePolicy(RequestCacheLevel.CacheIfAvailable);
            
            // assign the new policy to the request
            request.CachePolicy = rcpCheckCache;

            // execute the request
            HttpWebResponse response = null;
            try
            {
                response = (HttpWebResponse)request.GetResponse();
                // check if we hit the cache
                if(response.IsFromCache==false)
                {
                    Console.WriteLine("Didn't hit the cache");
                }

                // get the response stream.
                Stream responseStream = response.GetResponseStream();
                // use a stream reader that understands UTF8
                StreamReader reader = new StreamReader(responseStream, Encoding.UTF8);

                try
                {
                    html = reader.ReadToEnd();
                }
                finally
                {
                    // close the reader
                    reader.Close();
                }
                Console.WriteLine("Html retrieved: " + html);
            }
            catch (WebException we)
            {
                Console.WriteLine(we.ToString());
            }
        }
        #endregion 

        #region "14.18 Checking out a web server's custom error pages
        public static void GetCustomErrorPageLocations()
        {
            // MetaEdit can be gotten here: http://support.microsoft.com/kb/q232068/
            // Find metabase properties here
            // http://msdn.microsoft.com/library/default.asp?url=/library/en-us/iissdk/html/4930f687-3a39-4f7d-9bc7-56dbb013d2b5.asp

            // Sometimes the COM world is a rough place
            UInt32 E_RPC_SERVER_UNAVAILABLE = 0x800706BA;

            try
            {
                // This is a case sensitive entry in the metabase
                // You'd think it was misspelled but you would be mistaken
                const string WebServerSchema = "IIsWebServer";

                // set up to talk to the local IIS server
                string server = "localhost";

                // Create a dictionary entry for the IIS server with a fake
                // user and password.  Credentials would have to be provided
                // if you are running as a regular user
                using (DirectoryEntry w3svc = 
                    new DirectoryEntry(
                        string.Format("IIS://{0}/w3svc", server), 
                            "Domain/UserCode", "Password"))
                {
                    // can't talk to the metabase for some reason, bail
                    if (w3svc != null)
                    {
                        foreach (DirectoryEntry site in w3svc.Children)
                        {
                            if (site != null)
                            {
                                using (site)
                                {
                                    // check all web servers on this box
                                    if (site.SchemaClassName == WebServerSchema)
                                    {
                                        // get the metabase entry for this server
                                        string metabaseDir = 
                                            string.Format("/w3svc/{0}/ROOT", site.Name);

                                        if (site.Children != null)
                                        {
                                            // find the ROOT directory for each server
                                            foreach (DirectoryEntry root in site.Children)
                                            {
                                                using (root)
                                                {
                                                    // did we find the root dir for this site?
                                                    if (root != null && 
                                                        root.Name.Equals("ROOT", 
                                                            StringComparison.OrdinalIgnoreCase))
                                                    {
                                                        // get the HttpErrors
                                                        if (root.Properties.Contains("HttpErrors") == true)
                                                        {
                                                            // write them out
                                                            PropertyValueCollection httpErrors = root.Properties["HttpErrors"];
                                                            if (httpErrors != null)
                                                            {
                                                                for (int i = 0; i < httpErrors.Count; i++)
                                                                {
                                                                    //400,*,FILE,C:\WINDOWS\help\iisHelp\common\400.htm
                                                                    string[] errorParts = httpErrors[i].ToString().Split(',');
                                                                    Console.WriteLine("Error Mapping Entry:");
                                                                    Console.WriteLine("\tHTTP error code: {0}", errorParts[0]);
                                                                    Console.WriteLine("\tHTTP sub-error code: {0}", errorParts[1]);
                                                                    Console.WriteLine("\tMessage Type: {0}", errorParts[2]);
                                                                    Console.WriteLine("\tPath to error HTML file: {0}", errorParts[3]);
                                                                }
                                                            }
                                                        }
                                                    }
                                                }
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
            catch (COMException e)
            {
                // apparently it won't talk to us right now
                // this could be set up in a loop to retry.
                if (e.ErrorCode != (Int32)E_RPC_SERVER_UNAVAILABLE)
                {
                    throw;
                }
            }
        }
        #endregion

        #region "14.19 Determining the application mappings for ASP.NET set up on IIS
        public static void DumpASPNETAppMappings()
        {
            // MetaEdit can be gotten here: http://support.microsoft.com/kb/q232068/
            // Find metabase properties here
            // http://msdn.microsoft.com/library/default.asp?url=/library/en-us/iissdk/html/4930f687-3a39-4f7d-9bc7-56dbb013d2b5.asp

            // Sometimes the COM world is a rough place
            UInt32 E_RPC_SERVER_UNAVAILABLE = 0x800706BA;

            try
            {
                // This is a case sensitive entry in the metabase
                // You'd think it was misspelled but you would be mistaken
                const string WebServerSchema = "IIsWebServer";

                // set up to talk to the local IIS server
                string server = "localhost";

                // Create a dictionary entry for the IIS server with a fake
                // user and password.  Credentials would have to be provided
                // if you are running as a regular user
                using (DirectoryEntry w3svc = new DirectoryEntry(string.Format("IIS://{0}/w3svc", server), "Domain/UserCode", "Password"))
                {
                    // can't talk to the metabase for some reason, bail
                    if (w3svc != null)
                    {
                        foreach (DirectoryEntry site in w3svc.Children)
                        {
                            using (site)
                            {
                                if (site != null)
                                {
                                    // check all web servers on this box
                                    if (site.SchemaClassName == WebServerSchema)
                                    {
                                        // get the metabase entry for this server
                                        string metabaseDir =
                                            string.Format("/w3svc/{0}/ROOT", site.Name);

                                        if (site.Children != null)
                                        {
                                            // find the ROOT directory for each server
                                            foreach (DirectoryEntry root in site.Children)
                                            {
                                                using (root)
                                                {
                                                    // did we find the root dir for this site?
                                                    if (root != null &&
                                                        root.Name.Equals("ROOT", StringComparison.OrdinalIgnoreCase))
                                                    {
                                                        // get the Application Mappings in the ScriptMaps property
                                                        if (root.Properties.Contains("ScriptMaps") == true)
                                                        {
                                                            // write them out
                                                            PropertyValueCollection scriptMaps = root.Properties["ScriptMaps"];
                                                            if (scriptMaps != null)
                                                            {
                                                                for (int i = 0; i < scriptMaps.Count; i++)
                                                                {
                                                                    //.aspx,C:\WINDOWS\Microsoft.NET\Framework\v2.0.50110\aspnet_isapi.dll,1,GET,HEAD,POST,DEBUG
                                                                    string[] mappingParts = scriptMaps[i].ToString().Split(',');
                                                                    // The ASP.NET redirector is implemented in the 
                                                                    // aspnet_isapi.dll file so any extensions mapped to it
                                                                    // will be processed by asp.net
                                                                    if (mappingParts[1].ToUpper().IndexOf("ASPNET_ISAPI") != -1)
                                                                    {
                                                                        // write out details for the ASP.NET mappings
                                                                        Console.WriteLine("Extension Mappings:");
                                                                        Console.WriteLine("\tMapped Extension: {0}", mappingParts[0]);
                                                                        Console.WriteLine("\tHandler: {0}", mappingParts[1]);
                                                                        for (int j = 3; j < mappingParts.Length; j++)
                                                                            Console.WriteLine("\tHTTP VERB: {0}", mappingParts[j]);
                                                                    }
                                                                    else
                                                                    {
                                                                        // write out those unmapped items
                                                                        Console.WriteLine("Skipping {0} as it is not processed by ASP.NET", mappingParts[0]);
                                                                    }
                                                                }
                                                            }
                                                        }
                                                    }
                                                }
                                            }
                                        }
                                    }
                                }
                            }
                        }
                    }
                }
            }
            catch (COMException e)
            {
                // apparently it won't talk to us right now
                // this could be set up in a loop to retry.
                if (e.ErrorCode != (Int32)E_RPC_SERVER_UNAVAILABLE)
                {
                    throw;
                }
            }
        }
        #endregion
    }
}