private void btnStart_Click(object sender, EventArgs e) { if (down == null || down.Status == DownLoadStatus.Idle) { HttpDownLoadFile file = (HttpDownLoadFile)DownLoadFileFactory.CreateDownLoadFile(DownLoadType.HttpDownLoad, this.txtUrl.Text); down = new DownLoad(file, this.txtLocalPath.Text); down.SecondDownLoad += new SecondDownLoadEventHandler(down_SecondDownLoad); down.Start(); } }