public static CookieContainer theCC = new CookieContainer();

/// <summary>     
/// 登录方法(无验证码)     
/// </summary>     
/// <PARAM name="url">POST请求的地址</PARAM>     
/// <PARAM name="paramList">参数列表 例如 name=zhangsan&pass=lisi</PARAM>     
/// <PARAM name="referer">来源地址</PARAM>     
/// <RETURNS></RETURNS>     
public static string Login(String url, String paramList, string referer)
{
    HttpWebResponse res = null;
    HttpWebRequest req = null;
    string strResult = "";
    try
    {
        req = (HttpWebRequest)WebRequest.Create(url);
        //配置请求header     
        req.Headers.Add(HttpRequestHeader.AcceptCharset, "GBK,utf-8;q=0.7,*;q=0.3");
        req.Headers.Add(HttpRequestHeader.AcceptEncoding, "gzip,deflate,sdch");
        req.Headers.Add(HttpRequestHeader.AcceptLanguage, "zh-CN,zh;q=0.8");
        req.Accept = "application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5";
        req.KeepAlive = true;
        req.Referer = referer;
        req.Headers.Add(HttpRequestHeader.CacheControl, "max-age=0");
        req.UserAgent = "Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US) AppleWebKit/534.7 (KHTML, like Gecko) Chrome/7.0.517.5 Safari/534.7";
        req.Method = "POST";
        req.ContentType = "application/x-www-form-urlencoded";
        req.AllowAutoRedirect = true;
        //设置cookieContainer用来接收cookie     
        req.CookieContainer = theCC;
        StringBuilder UrlEncoded = new StringBuilder();
        //对参数进行encode     
        Char[] reserved = { '?', '=', '&' };
        byte[] SomeBytes = null;
        if (paramList != null)
        {
            int i = 0, j;
            while (i < paramList.Length)
            {
                j = paramList.IndexOfAny(reserved, i);
                if (j == -1)
                {
                    UrlEncoded.Append(HttpUtility.UrlEncode(paramList.Substring(i, paramList.Length - i)));
                    break;
                }
                UrlEncoded.Append(HttpUtility.UrlEncode(paramList.Substring(i, j - i)));
                UrlEncoded.Append(paramList.Substring(j, 1));
                i = j + 1;
            }
            SomeBytes = Encoding.UTF8.GetBytes(UrlEncoded.ToString());
            req.ContentLength = SomeBytes.Length;
            Stream newStream = req.GetRequestStream();
            newStream.Write(SomeBytes, 0, SomeBytes.Length);
            newStream.Close();
        }
        else
        {
            req.ContentLength = 0;
        }
        //返回请求     
        res = (HttpWebResponse)req.GetResponse();
        Encoding encode = System.Text.Encoding.GetEncoding("utf-8");
        Stream responseStream = null;
        if (res.ContentEncoding.ToLower() == "gzip")
        {
            responseStream = new System.IO.Compression.GZipStream(res.GetResponseStream(), System.IO.Compression.CompressionMode.Decompress);
        }
        else if (res.ContentEncoding.ToLower() == "deflate")
        {
            responseStream = new System.IO.Compression.DeflateStream(res.GetResponseStream(), System.IO.Compression.CompressionMode.Decompress);
        }
        else
        {
            responseStream = res.GetResponseStream();
        }
        StreamReader sr = new StreamReader(responseStream, encode);
        strResult = sr.ReadToEnd();
    }
    catch (Exception e)
    {
        //writeLog     
    }
    finally
    {
        res.Close();
    }
    return strResult;
}

/// <summary>  获取页面HTML     
///      
/// <PARAM name="url"></PARAM>     
/// <PARAM name="paramList"></PARAM>     
/// <RETURNS></RETURNS>     
public static string getPage(String url, string referer)
{
    HttpWebRequest req = (HttpWebRequest)WebRequest.Create(url);
    string strResult = string.Empty;
    req.Headers["If-None-Match"] = "36d0ed736e88c71:d9f";
    req.Referer = referer;
    req.CookieContainer = theCC;
    HttpWebResponse res = (HttpWebResponse)req.GetResponse();
    StreamReader sr = null;
    try
    {
        sr = new StreamReader(res.GetResponseStream(), Encoding.UTF8);
        strResult = sr.ReadToEnd();
    }
    catch (System.Exception ex)
    {
        //writeLog     
    }
    finally
    {
        sr.Close();
    }
    return strResult;
}

/// <summary>     
/// 模仿异步请求POST的方法     
/// </summary>     
/// <PARAM name="url"></PARAM>     
/// <PARAM name="referer"></PARAM>     
/// <PARAM name="methed"></PARAM>     
/// <PARAM name="paramList"></PARAM>     
/// <RETURNS></RETURNS>     
public static string VisitPage(string url, string referer, string paramList)
{
    HttpWebResponse response = null;
    string strResult = string.Empty;
    try
    {
        HttpWebRequest request = HttpWebRequest.Create(url) as HttpWebRequest;
        request.Method = "POST";
        request.KeepAlive = true;
        request.Referer = referer;
        request.Headers.Add(HttpRequestHeader.AcceptCharset, "GBK,utf-8;q=0.7,*;q=0.3");
        request.Headers.Add(HttpRequestHeader.AcceptEncoding, "gzip,deflate,sdch");
        request.Headers.Add(HttpRequestHeader.AcceptLanguage, "zh-CN,zh;q=0.8");
        request.Accept = "application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*/*;q=0.5";
        request.UserAgent = "Mozilla/5.0 (Windows; U; Windows NT 5.2; en-US) AppleWebKit/534.7 (KHTML, like Gecko) Chrome/7.0.517.5 Safari/534.7";
        request.ContentType = "application/x-www-form-urlencoded";
        request.CookieContainer = theCC;
        request.Headers.Add("X-Requested-With", "XMLHttpRequest");
        StringBuilder UrlEncoded = new StringBuilder();
        //对参数进行encode     
        Char[] reserved = { '?', '=', '&' };
        byte[] SomeBytes = null;
        if (paramList != null)
        {
            int i = 0, j;
            while (i < paramList.Length)
            {
                j = paramList.IndexOfAny(reserved, i);
                if (j == -1)
                {
                    UrlEncoded.Append(HttpUtility.UrlEncode(paramList.Substring(i, paramList.Length - i)));
                    break;
                }
                UrlEncoded.Append(HttpUtility.UrlEncode(paramList.Substring(i, j - i)));
                UrlEncoded.Append(paramList.Substring(j, 1));
                i = j + 1;
            }
            SomeBytes = Encoding.UTF8.GetBytes(UrlEncoded.ToString());
            request.ContentLength = SomeBytes.Length;
            Stream newStream = request.GetRequestStream();
            newStream.Write(SomeBytes, 0, SomeBytes.Length);
            newStream.Close();
        }
        response = (HttpWebResponse)request.GetResponse();
        Encoding encode = System.Text.Encoding.GetEncoding("utf-8");
        Stream responseStream = null;
        if (response.ContentEncoding.ToLower() == "gzip")
        {
            responseStream = new System.IO.Compression.GZipStream(response.GetResponseStream(), System.IO.Compression.CompressionMode.Decompress);
        }
        else if (response.ContentEncoding.ToLower() == "deflate")
        {
            responseStream = new System.IO.Compression.DeflateStream(response.GetResponseStream(), System.IO.Compression.CompressionMode.Decompress);
        }
        else
        {
            responseStream = response.GetResponseStream();
        }
        StreamReader sr = new StreamReader(responseStream, encode);
        strResult = sr.ReadToEnd();
    }
    catch
    {
        //dosomething     
    }
    finally
    {
        response.Close();
    }
    return strResult;
}

/// <summary>
/// Http下载文件
/// </summary>
public static string HttpDownloadFile(string url, string path)
{
    // 设置参数
    HttpWebRequest request = WebRequest.Create(url) as HttpWebRequest;
    //发送请求并获取相应回应数据
    HttpWebResponse response = request.GetResponse() as HttpWebResponse;
    //直到request.GetResponse()程序才开始向目标网页发送Post请求
    Stream responseStream = response.GetResponseStream();
    //创建本地文件写入流
    Stream stream = new FileStream(path, FileMode.Create);
    byte[] bArr = new byte[1024];
    int size = responseStream.Read(bArr, 0, (int)bArr.Length);
    while (size > 0)
    {
        stream.Write(bArr, 0, size);
        size = responseStream.Read(bArr, 0, (int)bArr.Length);
    }
    stream.Close();
    responseStream.Close();
    return path;
}