c# IO对文件进行操作开线程

就是使用using来自动开线程针对IO进行操作，完成之后自动释放内存，避免内存使用的卡顿

            using(SaveFileDialog fileDialog = new SaveFileDialog())
                {
                    fileDialog.Filter = "配置文件|*.pmx";
                    fileDialog.DefaultExt = ".pmx";
                    fileDialog.FileName = string.Format("{0}_info.pmx", mPackageType);
                    fileDialog.InitialDirectory = Application.StartupPath;
                    if (fileDialog.ShowDialog(this) == DialogResult.OK)
                    {
                        proposalPath = fileDialog.FileName;
                    }
                    else
                    {
                        return;
                    }
                }