C# 透過HTTP抓檔案回來

在Window視窗上放一個Button，一個ProgressBar，一個TextBlock（用來顯示ProgressBar的數值）
利用以下的函式，可以完成


        private void Btn_http_Click( object sender, RoutedEventArgs e )
        {
            // 非同步
            WebClient MyWebClient = new WebClient( );
            MyWebClient.DownloadFileCompleted += new AsyncCompletedEventHandler( Http_Completed );
            MyWebClient.DownloadProgressChanged += new DownloadProgressChangedEventHandler( Http_ProgressChanged );
            MyWebClient.DownloadFileAsync( new Uri( "http://www.joyplux.net/xplayer/download/JoyeDM/JoyeDMDownload_Setup.exe" ), @"c:\temp\JoyeDM.exe" );
        }


        private void Http_ProgressChanged( object sender, DownloadProgressChangedEventArgs e )
        {
            PgBar_Http.Value = e.ProgressPercentage; //控制ProcessBar顯示進度
            TxtBk_Percent.Text = e.ProgressPercentage + "%";
        }


        private void Http_Completed( object sender, AsyncCompletedEventArgs e )
        {
            MessageBox.Show( "Download completed!" );
        }