backgroundWorker 等待窗口的实现(loading窗口)

用模对话框显示窗口，后台执行文件的列出。。。方法如下

        public void chang()
        {
            try
            {
                Form loadingform = new loading();
                loadingform.StartPosition = FormStartPosition.CenterParent;
                loadingform.ShowDialog();
            }
            catch
            {
 
            }
        }

        private void ultraButton1_Click(object sender, EventArgs e)
        {            
           backgroundWorker1.RunWorkerAsync(); //开始后台执行

            chang();                            //调用等待窗口

            backgroundWorker1.CancelAsync();   //停止后台执行

            ultraButton1.Enabled = true;
            
        }


        private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
        {
            FindFile(@"C:\Users\王彬\Documents\");   //后台执行列出此目录下所有文件
        }

        private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            
        }

        private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            Application.OpenForms["loadingform"].Close(); //关闭等待窗口
        }