public static frmUpload CreateForm() { //判断是否存在该窗体,或时候该字窗体是否被释放过,如果不存在该窗体,则 new 一个字窗体 if (_instance == null || _instance.IsDisposed) { _instance = new frmUpload(); } return(_instance); }
private void tsbUp_Click(object sender, EventArgs e) { frmUpload progress = frmUpload.CreateForm(); progress.Show(); }