如何将datagridview中的数据导出到Excel中

using System;
using System.Collections.Generic;
using System.Text;
using System.Windows.Forms ;
using System.IO;

namespace OutputToExecl
{
    public class ExportXLS
    {
        public ExportXLS()
        {
 
        }
        public static void ExportDataGridViewToExcel(DataGridView dataGridview1)
        {
            SaveFileDialog saveFileDialog = new SaveFileDialog();
            saveFileDialog.Filter = "Execl files (*.xls)|*.xls";
            saveFileDialog.FilterIndex = 0;
            saveFileDialog.RestoreDirectory = true;
            saveFileDialog.CreatePrompt = true;
            saveFileDialog.Title = "导出Excel文件到";

            saveFileDialog.ShowDialog();

            Stream myStream;
            myStream = saveFileDialog.OpenFile();
            StreamWriter sw = new StreamWriter(myStream, System.Text.Encoding.GetEncoding("gb2312"));
            string str = "";
            try
            {
                //写标题 
                for (int i = 0; i < dataGridview1.ColumnCount; i++)
                {
                    if (i > 0)
                    {
                        str += "\t";
                    }
                    str += dataGridview1.Columns[i].HeaderText;
                }

                sw.WriteLine(str);
                //写内容
                for (int j = 0; j < dataGridview1.Rows.Count; j++)
                {
                    string tempStr = "";
                    for (int k = 0; k < dataGridview1.Columns.Count; k++)
                    {
                        if (k > 0)
                        {
                            tempStr += "\t";
                        }
                        tempStr += dataGridview1.Rows[j].Cells[k].Value.ToString();
                    }
                    sw.WriteLine(tempStr);
                }
                sw.Close();
                myStream.Close();
            }
            catch (Exception e)
            {
                MessageBox.Show(e.ToString());
            }
            finally
            {
                sw.Close();
                myStream.Close();
            }
        }

    }
}