在做WIN FORM程序中经常要使用到升级功能，就需要从服务器上下载最新扔软件程序。如何下载呢？代码实现如下：

        /// <summary>        

        /// c#,.net 下载文件        

        /// </summary>        

        /// <param name="URL">下载文件地址</param>       

        /// <param name="Filename">下载后的存放地址</param>        

        /// <param name="Prog">用于显示的进度条</param> 

        public void DownloadFile(string URL, string filename, System.Windows.Forms.ProgressBar prog, System.Windows.Forms.Label label1)

         {

            float percent = 0;

            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;

                 }

                 System.IO.Stream st = myrp.GetResponseStream();

                 System.IO.Stream so = new System.IO.FileStream(filename, System.IO.FileMode.Create);

                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();

                     so.Write(by, 0, osize);

                    if (prog != null)

                     {

                         prog.Value = (int)totalDownloadedByte;

                     }

                     osize = st.Read(by, 0, (int)by.Length);

                     percent = (float)totalDownloadedByte / (float)totalBytes * 100;

                     label1.Text = "当前补丁下载进度" + percent.ToString() + "%";

                     System.Windows.Forms.Application.DoEvents(); //必须加注这句代码，否则label1将因为循环执行太快而来不及显示信息

                 }

                 so.Close();

                 st.Close();

             }

            catch (System.Exception)

             {

                throw;

             }

         }