C#模拟http 发送post或get请求

    /// <summary>
    /// 模拟HTTP提交表单并获取返回数据
    /// POST
    /// </summary>
    /// <param name="Url">提交地址</param>
    /// <param name="postDataStr">参数</param>
    /// <param name="cookies">cookies</param>
    /// <returns></returns>
    public string HttpPost(string Url, string postDataStr, CookieCollection cookies)
    {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url);
        request.Method = "POST";
        request.ContentType = "application/x-www-form-urlencoded";
        request.ContentLength = Encoding.UTF8.GetByteCount(postDataStr);
        request.UserAgent = "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/44.0.2403.155 Safari/537.36";
        if (cookies != null)
        {
            request.CookieContainer = new CookieContainer();
            request.CookieContainer.Add(cookies);
        }
        using (StreamWriter myStreamWriter = new StreamWriter(request.GetRequestStream(), Encoding.GetEncoding("utf-8")))
        {
            myStreamWriter.Write(postDataStr);
            myStreamWriter.Flush();
        }

        HttpWebResponse response = (HttpWebResponse)request.GetResponse();

        StreamReader myStreamReader = new StreamReader(response.GetResponseStream(), Encoding.GetEncoding("utf-8"));
        string retString = myStreamReader.ReadToEnd();
        myStreamReader.Close();
        response.Close();

        return retString;
    }

    /// <summary>
    /// 模拟HTTP提交表单并获取返回数据
    /// GET
    /// </summary>
    /// <param name="Url">提交地址</param>
    /// <param name="postDataStr">参数</param>
    /// <returns></returns>
    public string HttpGet(string Url, string postDataStr)
    {
        HttpWebRequest request = (HttpWebRequest)WebRequest.Create(Url + (postDataStr == "" ? "" : "?") + postDataStr);
        request.Method = "GET";
        request.ContentType = "text/html;charset=UTF-8";

        HttpWebResponse response = (HttpWebResponse)request.GetResponse();
        Stream myResponseStream = response.GetResponseStream();
        StreamReader myStreamReader = new StreamReader(myResponseStream, Encoding.GetEncoding("utf-8"));
        string retString = myStreamReader.ReadToEnd();
        myStreamReader.Close();
        myResponseStream.Close();

        return retString;
    }    

在post的时候有时也用的到cookie，像登录163发邮件时候就需要发送cookie，所以在外部一个cookie属性随时保存 CookieContainer cookie = new CookieContainer();

*注意：有时候请求会重定向，但我们就需要从重定向url获取东西，像QQ登录成功后获取sid，但上面的会自动根据重定向地址跳转。我们可以用:
request.AllowAutoRedirect = false;设置重定向禁用，你就可以从headers的Location属性中获取重定向地址。