文件下载

private void button1_Click(object sender, EventArgs e)        {            string uil = "http://ime.files2.sogou.com/sogou_pinyin_68_6838.exe";                    //实例化WebClint对象            WebClient webClient = new WebClient();            /* WebClient.DownloadFileCompleted<事件>在异步文件下载操作完成时发生。            * 此事件在每次完成异步文件下载操作时引发。异步文件下载通过调用 DownloadFileAsync 方法启动。            * AsyncCompletedEventHandler 是此事件的委托。 AsyncCompletedEventArgs 类为事件处理程序提供事件数据。*/            webClient.DownloadFileCompleted += new AsyncCompletedEventHandler(webClient_DownloadFileCompleted);            webClient.DownloadProgressChanged += new DownloadProgressChangedEventHandler(webClient_DownloadProgressChanged);            webClient.DownloadFileAsync(new Uri(uil),Application.StartupPath+"\\"+Path.GetFileName(uil));                    }        void webClient_DownloadProgressChanged(object sender, DownloadProgressChangedEventArgs e)        {            progressBar1.Value = e.ProgressPercentage;        }        void webClient_DownloadFileCompleted(object sender, AsyncCompletedEventArgs e)        {            MessageBox.Show("完成","提示信息");        }