如何使用HttpWebRequest发布数据？

string url = "http://example.com/api";
string postData = "param1=value1&param2=value2";

HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);
request.Method = "POST";
request.ContentType = "application/x-www-form-urlencoded";
request.Timeout = 5000;

byte[] data = Encoding.UTF8.GetBytes(postData);
request.ContentLength = data.Length;

using (Stream stream = request.GetRequestStream())
{
    stream.Write(data, 0, data.Length);
}

using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
{
    using (StreamReader reader = new StreamReader(response.GetResponseStream()))
    {
        string result = reader.ReadToEnd();
        Console.WriteLine(result);
    }
}