//默认打开路径
        private string InitialDirectory = "D:\\";
        //统一对话框
        private bool InitialDialog(FileDialog fileDialog, string title)
        {
            fileDialog.InitialDirectory = InitialDirectory;//初始化路径
            fileDialog.Filter = "txt files (*.txt,*.*)|*.txt;*.*" ;//过滤选项设置，文本文件，所有文件。
            fileDialog.FilterIndex = 1;//当前使用第二个过滤字符串
            fileDialog.RestoreDirectory = true;//对话框关闭时恢复原目录
            fileDialog.Title = title;
            if (fileDialog.ShowDialog() == true)
            {
                for (int i = 1; i <= fileDialog.FileName.Length; i++)
                {
                    if (fileDialog.FileName.Substring(fileDialog.FileName.Length -i,1).Equals(@"\"))
                    {
                        //更改默认路径为最近打开路径
                        InitialDirectory = fileDialog.FileName.Substring(0, fileDialog.FileName.Length - i+1);
                        return true;
                    }
                }

                return true;
            }
            else
            {
                return false;
            }
        }        


            

        private void Open(object obj)
        {   
            OpenFileDialog openFileDialog = new OpenFileDialog();//打开文件对话框              
            if (InitialDialog(openFileDialog, "Open"))
            {
                using (Stream stream = openFileDialog.OpenFile())
                {
                    FileName = ((System.IO.FileStream)stream).Name;
                    // 执行相关文件操作
　　　　　　　　　　　　...
                }
            } 
        }

        private void Save(object obj)
        {
            SaveFileDialog saveFileDialog = new SaveFileDialog();//打开文件对话框              
            if (InitialDialog(saveFileDialog, "Save"))
            {
                using (Stream stream = saveFileDialog.OpenFile())
                {
                    FileName = ((System.IO.FileStream)stream).Name;
                    //执行保存动作
                    ...
                    MessageBox.Show("保存成功。");
                }
            }
        }