C# HttpWebRequest post 请求传参数

Dictionary<string, string> parameters = new Dictionary<string, string>(); //参数列表
parameters.Add("paraName", "paraValue");
string url = "";

HttpWebRequest request = null;
HttpWebResponse response = null;
Stream reqStream = null;
request = (HttpWebRequest)WebRequest.Create(url);
request.Method = "post"; //设置为post请求
request.ReadWriteTimeout = 5000;
request.KeepAlive = false;
request.ContentType = "application/x-www-form-urlencoded;charset=utf-8";
byte[] postData = Encoding.UTF8.GetBytes(BuildQuery(parameters, "utf8")); //使用utf-8格式组装post参数
reqStream=request.GetRequestStream();
reqStream.Write(postData, 0, postData.Length); 
response = (HttpWebResponse)request.GetResponse();


//组装请求参数
private string BuildQuery(IDictionary<string, string> parameters, string encode)
{
StringBuilder postData = new StringBuilder();
bool hasParam = false;
IEnumerator<KeyValuePair<string, string>> dem = parameters.GetEnumerator();
while (dem.MoveNext())
{
string name = dem.Current.Key;
string value = dem.Current.Value;
// 忽略参数名或参数值为空的参数
if (!string.IsNullOrEmpty(name))
{
if (hasParam)
{
postData.Append("&");
}
postData.Append(name);
postData.Append("=");
if (encode == "gb2312")
{
postData.Append(HttpUtility.UrlEncode(value, Encoding.GetEncoding("gb2312")));
}
else if (encode == "utf8")
{
postData.Append(HttpUtility.UrlEncode(value, Encoding.UTF8));
}
else
{
postData.Append(value);
}
hasParam = true;
}
}
return postData.ToString();
}