C#-HTTP请求Post_c# http post

/// <summary>
/// post发送字符串数据-可指定数据类型,可设置timeout
/// </summary>
/// <param name="Url"></param>
/// <param name="SendData"></param>
/// <param name="SendData"></param>
/// <param name="ContentType">指定数据类型(text/html, text/plain, text/css, text/javascript, image/jpeg, image/png, image/gif,application/x-www-form-urlencoded, multipart/form-data, application/json, application/xml)</param>
/// <param name="timeout">指定超时时间</param>
/// <param name="state">返回操作状态0:正常;远程服务器报错;数据提交超时</param>
/// <returns></returns>
public static string SendRequestPostData(string Url, string SendData, string ContentType, int timeout, Dictionary<string, string> headers
    , ref string Status, ref int StatusCode, string Tag, string LogName)
{
    Status = "OK";
    System.GC.Collect();//垃圾回收，回收没有正常关闭的http连接
    string strURL = Url;
    //设置最大连接数
    ServicePointManager.DefaultConnectionLimit = 200;
    //设置https验证方式
    if (Url.StartsWith("https", StringComparison.OrdinalIgnoreCase))
    {
	ServicePointManager.ServerCertificateValidationCallback =
		new RemoteCertificateValidationCallback(CheckValidationResult);
    }
    //创建一个HTTP请求  
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(strURL);
    //Post请求方式  
    request.Method = "POST";
    if (timeout != 0)
    {
	request.Timeout = timeout;
    }
    CookieContainer cookieContainer = new CookieContainer();
    request.CookieContainer = cookieContainer;
    request.AllowAutoRedirect = true;
    //内容类型
    request.ContentType = ContentType == null ? "text/html" : ContentType;
    if (headers != null)
    {
	foreach (string key in headers.Keys)
	{
	    request.Headers.Add(key, headers[key]);
	}
    }
 
    //设置参数，并进行URL编码 
 
    string paraUrlCoded = SendData;//System.Web.HttpUtility.UrlEncode(jsonParas);   
 
    byte[] payload;
    //将Json字符串转化为字节  
    payload = System.Text.Encoding.UTF8.GetBytes(paraUrlCoded);
    //设置请求的ContentLength   
    request.ContentLength = payload.Length;
    //发送请求，获得请求流 
 
    ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3 | SecurityProtocolType.Tls;
    Stream writer;
    try
    {
	writer = request.GetRequestStream();//获取用于写入请求数据的Stream对象
    }
    catch (Exception ex)
    {
	Status = ex.Message;
	T9.Util.LogUtil.WriteLog("SendRequestPostData方法出错[0]" + (Tag != null ? "[" + Tag + "]" : "") + ":" + ex.Message + "\r\n" + ex.StackTrace, LogName);
	writer = null;
	request.Abort();
	return null;
    }
    //将请求参数写入流
    writer.Write(payload, 0, payload.Length);
    writer.Close();//关闭请求流
    HttpWebResponse response = null;
    string postContent = null;
    try
    {
	//获得响应流
	response = (HttpWebResponse)request.GetResponse();
    }
    catch (WebException ex)
    {
	Status = ex.Status.ToString();
	T9.Util.LogUtil.WriteLog("SendRequestPostData方法出错[1]" + (Tag != null ? "[" + Tag + "]" : "") + ":" + ex.Message + "\r\n" + ex.StackTrace, LogName);
	response = ex.Response as HttpWebResponse;
    }
    finally
    {
	if (response == null)
	{
	    postContent = null;
	}
	else
	{
	    StatusCode = (int)response.StatusCode;
	    Stream s = response.GetResponseStream();
	    StreamReader sRead = new StreamReader(s);
	    postContent = sRead.ReadToEnd();
	    request.Abort();
	    response.Close();
	    sRead.Close();
	}
    }
    return postContent;//返回Json数据
}