private void dataTableToCsv(DataTable table, string file)
        {

            string title = "";

            FileStream fs = new FileStream(file, FileMode.OpenOrCreate);

            //FileStream fs1 = File.Open(file, FileMode.Open, FileAccess.Read);

            StreamWriter sw = new StreamWriter(new BufferedStream(fs), System.Text.Encoding.Default);

            for (int i = 0; i < table.Columns.Count; i++)
            {

                title += table.Columns[i].ColumnName + "\t"; //栏位：自动跳到下一单元格

            }

            title = title.Substring(0, title.Length - 1) + "\n";

            sw.Write(title);

            foreach (DataRow row in table.Rows)
            {

                string line = "";

                for (int i = 0; i < table.Columns.Count; i++)
                {

                    line += row[i].ToString().Trim() + "\t"; //内容：自动跳到下一单元格

                }

                line = line.Substring(0, line.Length - 1) + "\n";

                sw.Write(line);

            }

            sw.Close();

            fs.Close();
            MessageBox.Show("数据导出成功!", "提示", MessageBoxButtons.OK, MessageBoxIcon.Information);
        }

        public void m_mthExport()
        {
            //dataTableToCsv();
            SaveFileDialog dlg = new SaveFileDialog();
            dlg.Filter = "Execl files (*.xls)|*.xls";
            //dlg.Filter = "Excel 2003|*.xls|Excel 2007|*.xlsx";
            dlg.CheckFileExists = false;
            dlg.CheckPathExists = false;
            dlg.FilterIndex = 0;
            dlg.RestoreDirectory = true;
            dlg.CreatePrompt = false;
            dlg.Title = "保存为Excel文件";

            if (dlg.ShowDialog() == DialogResult.OK)
            {
                string ss = dlg.FileName;
                dataTableToCsv(dtSource,dlg.FileName);
            }
           // DataGridViewToExcel(m_objViewer.DgvReportList);
        }
        public void DataGridViewToExcel(DataGridView dgv)
        {
            SaveFileDialog dlg = new SaveFileDialog();
            dlg.Filter = "Execl files (*.xls)|*.xls";
            //dlg.Filter = "Excel 2003|*.xls|Excel 2007|*.xlsx";
            dlg.CheckFileExists = false;
            dlg.CheckPathExists = false;
            dlg.FilterIndex = 0;
            dlg.RestoreDirectory = true;
            dlg.CreatePrompt = false;
            dlg.Title = "保存为Excel文件";

            if (dlg.ShowDialog() == DialogResult.OK)
            {
                Stream myStream;
                myStream = dlg.OpenFile();
                StreamWriter sw = new StreamWriter(myStream, System.Text.Encoding.GetEncoding(-0));
                string columnTitle = "";
                try
                {
                    //写入列标题  
                    for (int i = 0; i < dgv.ColumnCount; i++)
                    {
                        if (i > 0)
                        {
                            columnTitle += "\t";
                        }
                        columnTitle += dgv.Columns[i].HeaderText;
                    }
                    sw.WriteLine(columnTitle);

                    //写入列内容  
                    for (int j = 0; j < dgv.Rows.Count; j++)
                    {
                        string columnValue = "";
                        for (int k = 0; k < dgv.Columns.Count; k++)
                        {
                            if (k > 0)
                            {
                                columnValue += "\t";
                            }
                            if (dgv.Rows[j].Cells[k].Value == null)
                                columnValue += "";
                            else
                                columnValue += dgv.Rows[j].Cells[k].Value.ToString().Trim();
                        }
                        sw.WriteLine(columnValue);
                    }
                    sw.Close();
                    myStream.Close();
                    MessageBox.Show("数据导出成功!", "提示", MessageBoxButtons.OK);
                }
                catch (Exception e)
                {
                    MessageBox.Show(e.ToString());
                }
                finally
                {
                    sw.Close();
                    myStream.Close();
                }
            }
        }