该静态函数执行一个 HTTP GET 操作，并将回应作为 String 返回。

/// <summary>  /// Get a response as a string, given a uri string.  /// </summary>  /// <param name="uriArg">Specifies a uri such as "http://www.google.com" or @"file://X:\dir\myFile.html"</param>  /// <returns>web response as a string.</returns>  /// <example>  /// try  /// {  ///    string uri = "http://www.google.zzz"; // note bad uri with zzz to exercise exception.  ///    string s = GetWebPageResponse( uri );   ///    Console.WriteLine( s );  /// }  /// catch ( WebException ex )  /// {  ///    // wex.Message could be something like: The remote server returned an error: (404) Not Found.  ///    string s = string.Format( "Request: {0}\nResult: {1}", uri, ex.Message );  ///    Console.WriteLine( s );  /// }  /// </example>  static string GetWebPageResponse(string uriArg)  {      Stream responseStream = WebRequest.Create(uriArg).GetResponse().GetResponseStream();        StreamReader reader = new StreamReader(responseStream);        return reader.ReadToEnd();  }    /// <summary>  /// Similar to GetWebPageResponse(string uriArg), but uses a user/pw to log in.  /// </summary>  /// <param name="uriArg">e.g. "http://192.168.2.1"</param>  /// <param name="userArg">e.g. "root"</param>  /// <param name="pwArg">e.g. "admin"</param>  /// <returns>string containing the http response.</returns>  /// <example>  /// // Example to get a response with DHCP table from my LinkSys router.  /// string s = GetWebPageResponse( "http://192.168.2.1/DHCPTable.htm", "root", "admin" );  /// </example>  static string GetWebPageResponse(string uriArg, string userArg, string pwArg)  {      Uri uri = new Uri(uriArg);      HttpWebRequest req = (HttpWebRequest)WebRequest.Create(uri);      CredentialCache creds = new CredentialCache();        // See http://msdn.microsoft.com/en-us/library/system.directoryservices.protocols.authtype.aspx for list of types.      const string authType = "basic";        creds.Add(uri, authType, new NetworkCredential(userArg, pwArg));      req.PreAuthenticate = true;      req.Credentials = creds.GetCredential(uri, authType);        Stream responseStream = req.GetResponse().GetResponseStream();        StreamReader reader = new StreamReader(responseStream);        return reader.ReadToEnd();  }