Http 下载文件 并显示进度条

        /// <summary>        
        /// HTTP 下载文件     
        /// Current Thread Download
        /// </summary>        
        /// <param name="URL">下载文件地址</param>        
        /// <param name="buffer">将下载的文件存入该字节数组</param>        
        /// <param name="Prog">用于显示的进度条</param>        
        public void DownloadFile(string URL, ref byte[] buffer, ProgressBar prog)
        {
            try
            {
                System.Net.HttpWebRequest Myrq = (System.Net.HttpWebRequest)System.Net.HttpWebRequest.Create(URL);
                System.Net.HttpWebResponse myrp = (System.Net.HttpWebResponse)Myrq.GetResponse();
                long totalBytes = myrp.ContentLength;
                if (prog != null)
                {
                    prog.Maximum = (int)totalBytes;
                }
                using (MemoryStream ms = new MemoryStream((int)totalBytes))
                {
                    Stream st = myrp.GetResponseStream();
                    long totalDownloadedByte = 0;
                    byte[] by = new byte[1024];
                    int osize = st.Read(by, 0, (int)by.Length);
                    while (osize > 0)
                    {
                        totalDownloadedByte = osize + totalDownloadedByte;
                        System.Windows.Forms.Application.DoEvents();
                        ms.Write(by, 0, osize);
                        if (prog != null)
                        {
                            prog.Value = (int)totalDownloadedByte;
                        }
                        osize = st.Read(by, 0, (int)by.Length);
                    }
                    buffer = ms.ToArray();
                    st.Close();
                }
            }
            catch (Exception ex)
            {
                buffer = null;
                Console.WriteLine(ex.Message);
            }
        }

嘻、 request 和 response 都比较好用。