自己用c#写的保存文件

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Text;
using System.IO;
using System.Windows.Forms;

public class SaveHelper
    {
        public static bool IsValidFileName(string fileName)
        {
            System.Diagnostics.Debug.Assert(fileName != null);
            bool isValid = true;
            try
            {
                FileInfo fileInfor = new FileInfo(fileName);
                if (fileInfor.Name != fileName)
                {
                    isValid = false;
                }
            }
            catch (ArgumentException ex)
            {
                isValid = false;
            }
            catch (PathTooLongException ex)
            {
                isValid = false;
            }
            catch (NotSupportedException ex)
            {
                isValid = false;
            }
            catch (Exception e)
            {
                //isValid = true;
            }
            return isValid;
        }
        public static bool IsReadOnly(string fileName)
        {
            bool isReadonly = false;
            try
            {
                FileInfo fileInfor = new FileInfo(fileName);
                if (fileInfor.Exists)
                {
                    isReadonly = fileInfor.IsReadOnly;
                }
                else
                {
                    System.Diagnostics.Debug.Fail("File is not exist.");
                }

            }
            catch (Exception ex)
            {
                System.Diagnostics.Debug.Fail(ex.Message);
            }
            return isReadonly;
        }

        private static string AddExtension(string filename, string ext,bool replace)
        {
            int ind = filename.LastIndexOf(".");
            if (ind < 0)
            {
                return filename + "." + ext;
            }
            else if (filename.Substring(ind + 1).ToLower() != ext.ToLower())
            {
                if (replace)
                    return filename.Substring(0, ind) + "." + ext;
                else
                    return filename + "." + ext;
            }
            else
            {
                return filename;
            }
        }

        public static void SavingWidgetDialog(string Name, string uid)
        {
            if ((Name == null) || (Name.Trim().Length == 0)
                || (uid == null) || uid.Trim().Length == 0)
                return;
            Stream stream = null;
            SaveFileDialog dialog = new SaveFileDialog();
            dialog.AddExtension = true;
            dialog.DefaultExt = "bidml";
            string filter = string.Format("(*.x)|*.x|{2} (*.*)|*.*");
            dialog.Filter = filter;
            dialog.FilterIndex = 1;
            dialog.RestoreDirectory = true;
            dialog.OverwritePrompt = false;
            dialog.Title = "保存";

            string tempfilename =AddExtension(Name, dialog.DefaultExt,true);
            if (WidgetSaveHelper.IsValidFileName(tempfilename))
            {
                dialog.FileName = tempfilename;
            }
            dialog.FileOk += new CancelEventHandler(dialog_FileOk);
            if (dialog.ShowDialog() == DialogResult.OK)
            {
                try
                {
                    if ((stream = dialog.OpenFile()) != null)
                    {
                        using (stream)
                        {
                            stream.Close();
                        }
                    }
                }
                catch (Exception ex)
                {
                    if (stream != null)
                        stream.Close();
                    string errorMessage = "lala";
                    string caption = "lalala";
                    try
                    {
                        File.Delete(dialog.FileName);
                    }
                    catch (Exception e)
                    {
                    }
                }
            }
        }

        private static void dialog_FileOk(object sender, CancelEventArgs e)
        {
            SaveFileDialog dialog = sender as SaveFileDialog;
            dialog.FileName = AddExtension(dialog.FileName, dialog.DefaultExt, false);
            if (File.Exists(dialog.FileName))
            {
                string overwriteMessage = "lala";
                string readonlyMessage = "lalala";
                string caption = "la";
 
                //window.Form.StartPosition = FormStartPosition.CenterScreen;
               
                if (SaveHelper.IsReadOnly(dialog.FileName))
                {
                    e.Cancel = true;
                }
                else
                {
                    //DialogResult dr = window.Form.ShowDialog();
                    if (dr != DialogResult.OK)
                    {
                        e.Cancel = true;
                    }
                }
            }
    
4000
    }
    }