Http 下载文件利用(response,request) 并显示进度条

http 下载文件利用(response,request) 并显示进度条
request 和 response 都比较好用

/// <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);
            }
        }