#region 方法【DataGridViewToExcel】：导出excel

        private void DataGridViewToExcel(DataGridView dgv)
        {
            SaveFileDialog saveFileDialog = new SaveFileDialog();
            saveFileDialog.Filter = "Execl files (*.xls)|*.xls";
            saveFileDialog.FilterIndex = 0;
            saveFileDialog.RestoreDirectory = true;
            saveFileDialog.CreatePrompt = true;
            saveFileDialog.Title = "保存为Excel";

            if (saveFileDialog.ShowDialog() == DialogResult.OK)
            {
                Stream stream;
                stream = saveFileDialog.OpenFile();
                StreamWriter streamWriter = new StreamWriter(stream, System.Text.Encoding.GetEncoding(-0));
                string columnTitle = "";
                try
                {
                    #region 写入列标题
                    for (int i = 0; i < dgv.ColumnCount; i++)
                    {
                        if (dgv.Columns[i].Visible == true)
                        {
                            if (i > 0)
                            {
                                columnTitle += "\t";
                            }
                            columnTitle += dgv.Columns[i].HeaderText;
                        }
                    }
                    streamWriter.WriteLine(columnTitle);
                    #endregion

                    #region 写入列内容
                    for (int j = 0; j < dgv.Rows.Count; j++)
                    {
                        string columnValue = "";
                        for (int k = 0; k < dgv.Columns.Count; k++)
                        {
                            if (dgv.Columns[k].Visible == true)
                            {
                                if (k > 0)
                                {
                                    columnValue += "\t";
                                }
                                if (dgv.Rows[j].Cells[k].Value == null)
                                {
                                    columnValue += "";
                                }
                                else
                                {
                                    columnValue += dgv.Rows[j].Cells[k].Value.ToString();
                                }
                            }
                        }
                        streamWriter.WriteLine(columnValue);
                    }
                    #endregion

                    streamWriter.Close();
                    stream.Close();
                }
                catch (Exception ex)
                {
                    MessageBox.Show(ex.ToString());
                }
            }
        }
        #endregion