如何将参数添加到WebRequest中？

string url = "https://example.com/api";
string method = "POST";
string parameters = "key1=value1&key2=value2";

WebRequest request = WebRequest.Create(url);
request.Method = method;
request.Timeout = 5000;

byte[] parameterBytes = Encoding.UTF8.GetBytes(parameters);
request.ContentLength = parameterBytes.Length;

using (Stream requestStream = request.GetRequestStream())
{
    requestStream.Write(parameterBytes, 0, parameterBytes.Length);
    requestStream.Close();
}

using (WebResponse response = request.GetResponse())
{
    using (StreamReader reader = new StreamReader(response.GetResponseStream()))
    {
        string responseData = reader.ReadToEnd();
        // 处理响应数据
    }
}