c# datagridview导出Excel文件 问题

今天vs2010c#开发做datagridview导出Excel文件时，发现一个问题，和大家探讨一下：

第一种方式：写流的方式

private void button_Excel_Click(object sender, EventArgs e)
        {
                  if (dataGridView1.Tag.ToString() == "1")
            {

SaveFileDialog saveFileDialog = new SaveFileDialog();
                    saveFileDialog.Filter = "Microsoft Office Execl 工作薄(*.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("gb2312"));
                    string str = "";
                    try
                    {
                        //写标题
                        for (int i = 0; i < this.dataGridView1.ColumnCount; i++)
                        {
                            if (i > 0)
                            {
                                str += "\t";
                            }
                            str += this.dataGridView1.Columns[i].HeaderText;
                        }
                        sw.WriteLine(str);
                        //写内容
                        for (int j = 0; j < this.dataGridView1.Rows.Count; j++)
                        {
                            string tempStr = "";
                            for (int k = 0; k < this.dataGridView1.Columns.Count; k++)
                            {
                                if (k > 0)
                                {
                                    tempStr += "\t";
                                }
                                tempStr += this.dataGridView1.Rows[j].Cells[k].Value.ToString();
                            }

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

}
            else
            {

MessageBox.Show("请先转换格式，再导出excel文件！", "提示");

}

}

这种方式也能导出excel文件，不过是假的，当你打开之后再关闭时，会提示你，另存为新的excel文件，所以比较烦人。

另外，程序运行完后，会提示：未将对象引用设置到对象的实例；

应该是“ tempStr += this.dataGridView1.Rows[j].Cells[k].Value.ToString();”这行，，不知道什么原因。

基于以上原因，程序中没有采用这个方式。

第二种方式：新建excel表格，需要添加相应的引用；

private void button_Excel_Click(object sender, EventArgs e)
        {
            if (dataGridView1.Tag.ToString() == "1")
            {
                Microsoft.Office.Interop.Excel.Application excel = new Microsoft.Office.Interop.Excel.Application();
                Microsoft.Office.Interop.Excel.Workbook workbook;
                Microsoft.Office.Interop.Excel.Worksheet worksheet;
                excel.Visible = true;                            //是Excel可见
                workbook = excel.Workbooks.Add(XlWBATemplate.xlWBATWorksheet);
                worksheet = (Worksheet)workbook.Worksheets[1];
                System.Data.DataTable ecpTable = null;
                ecpTable = (System.Data.DataTable)dataGridView1.DataSource;
                for (int r = 0; r < ecpTable.Rows.Count; r++)
                {
                    for (int i = 0; i < ecpTable.Columns.Count; i++)
                    {
                        worksheet.Cells[r + 1, i + 1] = ecpTable.Rows[r][i].ToString();
                    }
                 }
            }
            else
            { MessageBox.Show("请先转换格式，再导出excel文件！", "提示"); }

}

这种方式比较成功，你能看到导入的数据。最后采用了这种方式。