.net 4.0 以下HttpWebRequest Header 修改hosts方法

.net 4.0 以下HttpWebRequest Header 修改hosts方法 特此记录

 public class CusteredHeaderCollection : WebHeaderCollection
    {
        public bool HostHeaderValueReplaced { get; private set; }

        public string ClusterUrl { get; private set; }

        public CusteredHeaderCollection(string commonClusterUrl) : base()
        {
            if (string.IsNullOrEmpty("commonClusterUrl"))
                throw new ArgumentNullException("commonClusterUrl");

            this.ClusterUrl = commonClusterUrl;
        }

        public override string ToString()
        {
            this["Host"] = this.ClusterUrl;
            string tmp = base.ToString();
            this.HostHeaderValueReplaced = true;

            return tmp;
        }

    }

   HttpWebRequest request = (HttpWebRequest)WebRequest.Create(uri);

  FieldInfo headersFieldInfo = request.GetType().GetField("_HttpRequestHeaders", System.Reflection.BindingFlags.NonPublic
                                                   | System.Reflection.BindingFlags.Instance
                                                   | System.Reflection.BindingFlags.GetField);

                CusteredHeaderCollection WssHeaders = new CusteredHeaderCollection(sDomain);

                headersFieldInfo.SetValue(request, WssHeaders);

                request.Proxy = null;