EXCEL导入到DataSet

 /// </summary>
        /// <param name="fileName">Excel全路径文件名</param>
        /// <returns>导入成功的DataSet</returns>
        public DataSet ImportExcel(string fileName)
        {
            //判断是否安装EXCEL
            Microsoft.Office.Interop.Excel.Application xlApp = new Microsoft.Office.Interop.Excel.ApplicationClass();
            if (xlApp == null)
            {
                _ReturnStatus = -1;
                _ReturnMessage = "无法创建Excel对象，可能您的计算机未安装Excel";
                return null;
            }
            //判断文件是否被其他进程使用            
            Microsoft.Office.Interop.Excel.Workbook workbook;
            try
            {
                workbook = xlApp.Workbooks.Open(fileName, 0, false, 5, "", "", false, Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "", true, false, 0, true, 1, 0);
            }
            catch(Exception ex)
            {
                _ReturnStatus = -1;
                _ReturnMessage = "Excel文件处于打开状态，请保存关闭,"+ex.Message;
                return null;
            }

            //获得所有Sheet名称
            int n = workbook.Worksheets.Count;
            string[] SheetSet = new string[n];
            System.Collections.ArrayList al = new System.Collections.ArrayList();
            for (int i = 1; i <= n; i++)
            {
                SheetSet[i - 1] = ((Microsoft.Office.Interop.Excel.Worksheet)workbook.Worksheets[i]).Name;
            }

            //释放Excel相关对象
            workbook.Close(null, null, null);
            xlApp.Quit();
            if (workbook != null)
            {
                System.Runtime.InteropServices.Marshal.ReleaseComObject(workbook);
                workbook = null;
            }
            if (xlApp != null)
            {
                System.Runtime.InteropServices.Marshal.ReleaseComObject(xlApp);
                xlApp = null;
            }
            GC.Collect();

            DataSet ds = new DataSet();
            string connStr = " Provider = Microsoft.Jet.OLEDB.4.0 ; Data Source = " + fileName + ";Extended Properties=Excel 8.0";
            using (OleDbConnection conn = new OleDbConnection(connStr))
            {
                conn.Open();
                OleDbDataAdapter da;
                for (int i = 1; i <= n; i++)
                {
                    string sql = "select * from [" + SheetSet[i - 1] + "$A:Z] ";
                    da = new OleDbDataAdapter(sql, conn);
                    da.Fill(ds, SheetSet[i - 1]);
                    da.Dispose();
                }
                conn.Close();
                conn.Dispose();
            }
            return ds;
        }