private void buttonToExcel_Click(object sender, EventArgs e)
        {
  
            SaveFileDialog saveFileDialog = new SaveFileDialog();
            saveFileDialog.Filter = "Execl files (*.xls)|*.xls";
            saveFileDialog.FilterIndex = 0;
            saveFileDialog.RestoreDirectory = true;
            saveFileDialog.CreatePrompt = true;
            saveFileDialog.Title = "Export Excel File To";
            saveFileDialog.ShowDialog();
            Stream myStream;
            myStream = saveFileDialog.OpenFile();
            StreamWriter sw = new StreamWriter(myStream, System.Text.Encoding.GetEncoding(-0));
            string str = "";
            try
            {
                //写标题
                for (int i = 0; i < this.dataGridView3.ColumnCount; i++)
                {
                    if (i > 0)
                    {
                        str += "\t";
                    }

                    str += this.dataGridView3.Columns[i].HeaderText;
                }
                sw.WriteLine(str);
                //写内容
                for (int j = 0; j < this.dataGridView3.Rows.Count; j++)
                {
                    string tempStr = "";
                    for (int k = 0; k < this.dataGridView3.Columns.Count; k++)
                    {
                        if (k > 0)
                        {
                            tempStr += "\t";
                        }
                        tempStr += this.dataGridView3.Rows[j].Cells[k].Value + "";
                    }
                    sw.WriteLine(tempStr);
                }

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

            finally
            {
                sw.Close();
                myStream.Close();
            }     
            MessageBox.Show("OK");
        }