采用代理调用搜索服务

 换 代理 IP
 和数据采集原理 差不多的。
http://www.haozs.net/proxyip/

///  <summary>
        ///  下载文件
        ///  </summary>
        ///  <param name="PageUrl">网址 </param>
        ///  <param name="filename">保存文件路径 </param>
        public void DownFile(string PageUrl, string filename)
        {
            if (!Directory.Exists(filename))
            {
                Directory.CreateDirectory(filename);
            }
            string  path = PageUrl.Substring(PageUrl.LastIndexOf("/") + 1);
            string dirname = filename + "\\" + path;


            if (File.Exists(dirname))
            {
                return;
            }
            else
            {
                try
                {                    
                    WebClient wc = new WebClient();
                    WebProxy wp = new WebProxy(al[proxy].ToString(), true);
                    wc.Proxy = wp;
                    wc.DownloadFile(PageUrl, dirname);
                }
                catch (WebException ex)
                {                   
                    if (ex.Status == WebExceptionStatus.ProtocolError)
                    {
                        //文件未找到--跳出 
                        //MessageBox.Show(ex.ToString());
                        return;
                    }
                    else
                    {
                        //换代理 IP
                        //MessageBox.Show(ex.ToString());
                        proxy++;
                        if (proxy >= al.Count)
                        {
                            al = ReadIPproxy("e:\\test.txt");//初始化代理   IP
                        }
                        DownFile(PageUrl, filename);
                    }
                }
            }

        }

＝＝＝＝＝＝＝＝＝＝
///  <summary>
        ///  请求失败的时候，反复操作
        ///  </summary>
        ///  <param name="PageUrl"> </param>
        ///  <returns> </returns>
        public string ToServer(string PageUrl)
        {
            string responseFromServer = "";
          
            try
            {                
                while (1 == 1)
                {
                    WebRequest request = WebRequest.Create(PageUrl);
                    WebProxy wp = new WebProxy(al[proxy].ToString(), true);
                    request.Proxy = wp;
                    request.Timeout = 1000 * 45;

                    HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                    Stream dataStream = response.GetResponseStream();
                    StreamReader reader=null;
                 
                        reader = new StreamReader(dataStream, System.Text.Encoding.Default);
                        responseFromServer = reader.ReadToEnd();
                    
                    reader.Close();
                    dataStream.Close();
                    response.Close();
                    if (responseFromServer.Contains("refresh")  ¦ ¦ responseFromServer == "")
                    {
                        proxy++;
                        if (proxy >= al.Count)
                        {
                            al = ReadIPproxy("e:\\test.txt");//初始化代理   IP
                        }
                        //ToServer(PageUrl);
                    }
                    else
                    {
                        break;
                    }
                }
            }
            catch (WebException ex)
            {                
                if (ex.Status == WebExceptionStatus.ProtocolError)
                {                   
                    responseFromServer = "";
                }
                else
                {
                    proxy++;
                    if (proxy >= al.Count)
                    {
                        al = ReadIPproxy("e:\\test.txt");//初始化代理   IP
                    }
                    ToServer(PageUrl);
                }
            }           
            return responseFromServer;
        }