private void ToExcelbtn_Click(object sender, EventArgs e)
{
    try
    {
        SaveFileDialog saveFileDialog = new SaveFileDialog();
        saveFileDialog.Filter = "Excel files (*.xls)|*.xls";
        saveFileDialog.FilterIndex = 0;
        saveFileDialog.RestoreDirectory = true;
        saveFileDialog.Title = "匯出屬性表為Excel";
        if (saveFileDialog.ShowDialog(this) == DialogResult.OK)
        {
            Stream myStream;
            myStream = saveFileDialog.OpenFile();
            StreamWriter sw = new StreamWriter(myStream, System.Text.Encoding.GetEncoding(-0));
            string str = "";
            try
            {
                //寫標題
                for (int i = 1; i < gridView1.Columns.Count; i++)
                {
                    if (i > 1)
                    {
                        str += "\t";
                    }
                    str += gridView1.Columns[i].FieldName;
                }

               sw.WriteLine(str);
                //寫內容
                for (int j = 1; j <= gridView1.RowCount; j++)
                {
                    string tempStr = "";
                    for (int k = 1; k < gridView1.Columns.Count; k++)
                    {
                        if (k > 1)
                        {
                            tempStr += "\t";
                        }
                        tempStr += gridView1.GetRowCellValue(j, gridView1.Columns[k]);
                    }
                    sw.WriteLine(tempStr);
                }
                sw.Close();
                myStream.Close();
                MessageBox.Show("資料已成功匯出!", "匯出為Excel");
            }
            catch (Exception ex)
            {
                MessageBox.Show(ex.ToString());
                LogHelper.Error(ex.Message);
            }
            finally
            {
                sw.Close();
                myStream.Close();
            }
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
        return;
    }
}