c# datagridview导出excel(写文本)

using System.IO;

//导出到execl
public void Excel(DataGridView dgv)
{
SaveFileDialog saveFileDialog = new SaveFileDialog();
saveFileDialog.Filter = "Execl files (*.xls)|*.xls";
saveFileDialog.FilterIndex = 0;
saveFileDialog.RestoreDirectory = true;
saveFileDialog.CreatePrompt = true;
saveFileDialog.Title = "Export Excel File";
saveFileDialog.ShowDialog();
if (saveFileDialog.FileName == "")
return;
Stream myStream;
myStream = saveFileDialog.OpenFile();
StreamWriter sw = new StreamWriter(myStream, System.Text.Encoding.GetEncoding(-0));
string str = "";
try
{
//寫dataGridView1表標題
for (int i = 0; i < dgv.ColumnCount; i++)
{
if (i > 0)
{
str += "\t";
}
str += dgv.Columns[i].HeaderText.Trim();
}
sw.WriteLine(str);

//寫dataGridView1表內容
for (int j = 0; j < dgv.Rows.Count; j++)
{
string tempStr = "";
for (int k = 0; k < dgv.Columns.Count; k++)
{
if (k > 0)
{
tempStr += "\t";
}
//tempStr += dataGridView1.Rows[j].Cells[k].Value.ToString().Trim() ;
tempStr += dgv.Rows[j].Cells[k].Value;

//要增加對含數字的文字類，如身份証號
//.........欠對身份証號處理，以免在EXCEL打開時被自動轉數字
}
sw.WriteLine(tempStr);
}
sw.Close();
myStream.Close();
}

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