C#中导出到Excel中的数据居中显示并且要显示字段名称！
麻烦大家帮我看一下下面这个关于C#中把查询出来的数据导出到Excel里边，并且进行打印，以下代码即可实现导出到Excel里面，但是没有显示字段名称，直接就把数据给显示出来了，我是想让导出到Excel里面的数据居中显示，并且把字段的名称也显示出来，以下代码在那些地方需要进行修改，以能够满足以上要求，请各位高手指点，小弟在此表示衷心感谢！


  private void excelToolStripMenuItem_Click_1(object sender, EventArgs e)
  {


  SaveFileDialog saveFileDialog = new SaveFileDialog();
  saveFileDialog.Filter = "Execl files (*.xls)|*.xls";
  saveFileDialog.FilterIndex = 0;
  saveFileDialog.RestoreDirectory = true;
  saveFileDialog.CreatePrompt = false;
  saveFileDialog.Title = "导出Excel文件到";


  if (saveFileDialog.ShowDialog() == DialogResult.Cancel)
  return;
  Stream myStream;
  myStream = saveFileDialog.OpenFile();
  StreamWriter sw = new StreamWriter(myStream, System.Text.Encoding.GetEncoding("gb2312")); //gb2312 

  try
  {
  //写标题 
  for (int i = 0; i < dataGridView1.ColumnCount; i++)
  {
  if (i == 0) dataGridView1.Columns[i].HeaderText = "序号";
  if (i > 0)
  {
  std += "\t";
  }

  std += dataGridView1.Columns[i].HeaderText;
  }

  sw.WriteLine(str);

  //写内容 

  for (int j = 0; j < dataGridView1.Rows.Count - 1; j++)
  {
  tempStr = "";

  for (int k = 0; k < dataGridView1.Columns.Count; k++)
  {

  if (k == 0 && j < (dataGridView1.Rows.Count - 2))
  dataGridView1.Rows[j].Cells[k].Value = j + 1;

  if (k > 0)
  {
  tempStr += "\t";
  }
  tempStr += dataGridView1.Rows[j].Cells[k].Value.ToString();
  }

  sw.WriteLine(tempStr);
  }
  sw.Close();
  myStream.Close();
  }
  catch (Exception ex)
  {
  MessageBox.Show(ex.ToString());
  }
  finally
  {
  sw.Close();
  myStream.Close();
  }






  }









  private void 导出ExcelToolStripMenuItem_Click(object sender, EventArgs e)
  {


  SaveFileDialog saveFileDialog = new SaveFileDialog();
  saveFileDialog.Filter = "Execl files (*.xls)|*.xls";
  saveFileDialog.FilterIndex = 0;
  saveFileDialog.RestoreDirectory = true;
  saveFileDialog.CreatePrompt = false;
  saveFileDialog.Title = "导出Excel文件到";


  if (saveFileDialog.ShowDialog() == DialogResult.Cancel)
  return;
  Stream myStream;
  myStream = saveFileDialog.OpenFile();