xml 导入
        public static System.Data.DataTable GetXmlTable(string fileName)
        {
            System.Data.DataSet dataSetXml;
            System.Data.DataTable dataTableXml;          
            dataSetXml = new DataSet();
            dataTableXml = new System.Data.DataTable();
            try
            {
                dataSetXml.ReadXml(fileName);
                dataTableXml = dataSetXml.Tables[1];          

            }
            catch (Exception ex)
            {
                Console.WriteLine(ex.ToString());
            }
            return dataTableXml;
        }
xml导出
    protected void ReadDataSetToXML(DataSet ds, string filePath)
    {
        FileStream fs = new FileStream(filePath, FileMode.Create, FileAccess.Write);
        XmlTextWriter xtw = new XmlTextWriter(fs, System.Text.Encoding.UTF8);
        ds.WriteXml(xtw, XmlWriteMode.IgnoreSchema);
        xtw.Close();
        fs.Close();
    }
Excel导入
        public static System.Data.DataTable GetExcelTable(string fileName, int dataStartLine, int nameLine, int columnCount)
        {
            System.Data.DataTable dtRet = null;
            DataRow dr;
            Application app = null;
            Workbook wb = null;
            Worksheet ws;
            Range range;
            object objMiss = null;
            int iRow;
            StringBuilder sbTemp;
            string sTemp = string.Empty;

            Console.WriteLine(DateTime.Now.ToLongTimeString() + " 正在读取Excel数据");
            objMiss = System.Reflection.Missing.Value;
            try
            {
                sbTemp = new StringBuilder();
                dtRet = new System.Data.DataTable();
                app = new Application();
                app.DisplayAlerts = false;
                app.Visible = false;
                wb = app.Workbooks.Open(fileName, 1, true, objMiss, objMiss, objMiss, objMiss,
                    objMiss, objMiss, objMiss, objMiss, objMiss, objMiss, objMiss, objMiss);
                ws = (Worksheet)wb.Sheets[1];

                for (int i = 1; i <= columnCount; i++)
                {
                    range = (Range)ws.get_Range(num2Char(i) + nameLine, objMiss);
                    if (range.Formula.ToString().Length > 0)
                    {
                        dtRet.Columns.Add(range.Formula.ToString().Trim(), typeof(string));
                    }
                    else
                    {
                        columnCount--;
                        i--;
                    }
                }

                iRow = dataStartLine;
                while (true)
                {
                    dr = dtRet.NewRow();
                    sbTemp.Length = 0;
                    for (int i = 1; i <= columnCount; i++)
                    {
                        range = (Range)ws.get_Range(num2Char(i) + iRow, objMiss);
                        try
                        {
                            sTemp = range.Formula.ToString();
                        }
                        catch (System.Runtime.InteropServices.COMException)
                        {
                            sTemp = string.Empty;
                        }
                        sbTemp.Append(sTemp);
                        dr[i - 1] = sTemp;
                    }
                    if (sbTemp.Length > 0)
                    {
                        dtRet.Rows.Add(dr);
                        iRow++;
                    }
                    else
                    {
                        break;
                    }
                }
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                wb.Close(false, objMiss, objMiss);
                app.Quit();
                app = null;
            }
            Console.WriteLine(DateTime.Now.ToLongTimeString() + " Excel数据读取完毕");

            return dtRet;
        }
Excel导出
    protected void ExportOfExcel()
    {
        Response.Clear();
        Response.Buffer = true;
        Response.Charset = "GB2312";
        Response.AppendHeader("Content-Disposition", "attachment;filename=Publisher.xls");
        Response.ContentEncoding = System.Text.Encoding.UTF7;
        // Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");如果设置为 GetEncoding("GB2312"),导出的文件将会出现乱码。

        //设置输出文件类型为excel文件。
        Response.ContentType = "application/ms-excel";
        this.EnableViewState = false;
        System.Globalization.CultureInfo myCItrad = new System.Globalization.CultureInfo("ZH-CN", true);
        System.IO.StringWriter oStringWriter = new System.IO.StringWriter(myCItrad);
        System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);
        this.GridView1.RenderControl(oHtmlTextWriter);
        Response.Write(oStringWriter.ToString());
        Response.End();
    }
Access,FoxPro等导入
     private static System.Data.DataTable getOleDbTable(string tableName, string fileName, string connString)
        {
            OleDbDataAdapter oda;
            string sql;
            System.Data.DataTable dtRet = new System.Data.DataTable();

            sql = "select * from " + tableName;
            oda = new OleDbDataAdapter(sql, connString);
            oda.Fill(dtRet);

            return dtRet;
        }