各位老师好，C#winform中的下载问题

想要在winform中通过点击一个button的方式把文件（使用的是文件的直接下载的地址url）下载到电脑中的某个地方，请问有老师可以教一下吗

// 最简语句，自行扩充
HttpWebRequest http = (HttpWebRequest)WebRequest.Create(url);
try
{
    HttpWebResponse hwr = (HttpWebResponse)http.GetResponse();
    Stream s = hwr.GetResponseStream();
    int length = (int)hwr.ContentLength;
    byte[] bt = new byte[length];
    int bufferlength = 1024 * 256;
    long sum = 0;
    while (sum < length)
    {
        byte[] bytes = new byte[bufferlength];
        int readbytes = s.Read(bytes, 0, bytes.Length);
        Array.Copy(bytes, 0, bt, sum, readbytes);
        sum += readbytes;
    }
    FileStream fs = new FileStream(fileName, FileMode.Create);
    BinaryWriter bw = new BinaryWriter(fs);
    bw.Write(bt);
    bw.Flush();
}

            fileName=@"c:\windows\system32\a.txt";
            FileInfo fi = new FileInfo(fileName);
            string folder = Regex.Replace(fi.FullName, @"[^/\\]+$", "", RegexOptions.IgnoreCase);
            if (!Directory.Exists(folder))
            {
                Directory.CreateDirectory(folder);
            }

加到FileStream前边

button的点击事件里发送http get请求指定url，然后在response里获取你要的文件，再自行保存