通過代理下載文件

//source 元文件地址  fileName 保存地址

 private void DownloadFile(string source, string fileName)
        {
            try
            {
                //WebProxy _WP = new WebProxy(ProxyName, ProxyPort);
                FileStream localStream;
                //create   a   web   Httprequest    
                HttpWebRequest wReq = (HttpWebRequest)HttpWebRequest.Create(source);
                //set   the   address   and   port   of   the   proxy   server    
                WebProxy wp = new WebProxy("192.168.11.8", 8080);

                wp.BypassProxyOnLocal = true;
                ICredentials credentials = new NetworkCredential("sun", "sun");
                wp.Credentials = credentials;

                //set   the   web   request's   proxy   server               
                wReq.Proxy = wp;
                //create   a   web   Httpresponse    
                HttpWebResponse wResp = (HttpWebResponse)wReq.GetResponse();
                //write   the   response   to   a   stream    
                Stream respStream = wResp.GetResponseStream();
                //create   a   new   file   to   receive   the   response   stream    
                localStream = new FileStream(fileName, FileMode.Append, FileAccess.Write);

                BinaryReader reader = new BinaryReader(respStream);
                //set   the   receive   binary   buffer    
                const int BufferSize = 102400;
                byte[] buffer = new Byte[BufferSize];
                bool bFinished = false;
                int dataRead;

                //just   write   the   buffer   to   the   binaryReader   again   and   again    
                do
                {
                    try
                    {
                        dataRead = reader.Read(buffer, 0, BufferSize);
                        if (dataRead == 0)
                            bFinished = true;
                        localStream.Write(buffer, 0, dataRead);
                    }
                    catch
                    {
                        localStream.Close();
                        respStream.Close();
                    }
                } while (!bFinished);
                //close   all   file   stream    
                localStream.Close();
                respStream.Close();
                //ShowLog("Download   finished");
            }
            catch (Exception ex)
            {
                throw new Exception("下載失敗，原因是：" + ex.Message, ex);
            }
        }