C#大数据导出到Excel

工作过程中经常会用到将数据导出到Excel中，一般情况下需要导出的数据都是几百几千条或者上万条，这都没有什么问题，但有时候会遇到特殊的需求，客户要求把几十万条甚至上百万条的数据导出到Excel中，这就比较麻烦了。当数据量很大导出到Excel表格的时候通常会遇到两个问题：一个是内存溢出，由于需要处理的数据量比较大，导致Excel占用的内存过多从而导致数据还没有导出完就因为内存溢出而失败；另一个是每张Excel表单最多只能有65536行，所以当DataTable或DataSet中数据多于65536行时会报错，这时候需要考虑Excel分页功能。

/// <summary>    /// 将DataTable数据导出到Excel表    /// </summary>    /// <param name="dtTmp">要导出的DataTable</param>    /// <param name="filePath">Excel的保存路径及名称</param>    public void DataTabletoExcel(System.Data.DataTable dtTmp, string filePath)    {        if (dtTmp == null)        {            return;        }        long rowNum = dtTmp.Rows.Count;//行数        int columnNum = dtTmp.Columns.Count;//列数        m_xlApp = new Excel.Application();        m_xlApp.DisplayAlerts = false;//不显示更改提示        m_xlApp.Visible = false;        Excel.Workbooks workbooks = m_xlApp.Workbooks;        Excel.Workbook workbook = workbooks.Add(Excel.XlWBATemplate.xlWBATWorksheet);        Excel.Worksheet worksheet = (Excel.Worksheet)workbook.Worksheets[1];//取得Sheet1        try        {            //单张Excel表格最大行数            if (rowNum > 65536)            {                long pageRows = 65535;  //定义每页显示的行数,行数必须小于65536                int scount = (int)(rowNum / pageRows);  //导出数据生成的表单数                if (scount * pageRows < rowNum) //当总行数不被pageRows整除时，经过四舍五入可能页数不准                {                    scount = scount + 1;                }                for (int sc = 1; sc <= scount; sc++)                {                    if (sc > 3) //这里由1改为3，20140922                    {                        object missing = System.Reflection.Missing.Value;                        worksheet = (Excel.Worksheet)workbook.Worksheets.Add(                                    missing, missing, missing, missing);    //添加一个sheet                    }                    else                    {                        worksheet = (Excel.Worksheet)workbook.Worksheets[sc];   //取得sheet1                    }                    string[,] datas = new string[pageRows + 1, columnNum];                    for (int i = 0; i < columnNum; i++) //写入字段                    {                        datas[0, i] = dtTmp.Columns[i].Caption; //表头信息                    }                    Excel.Range range = worksheet.get_Range(worksheet.Cells[1, 1], worksheet.Cells[1, columnNum]);                    range.Interior.ColorIndex = 15; //15代表灰色                    range.Font.Bold = true;                    range.Font.Size = 9;                    int init = int.Parse(((sc - 1) * pageRows).ToString());                    int r = 0;                    int index = 0;                    int result;                    if (pageRows * sc >= rowNum)                    {                        result = (int)rowNum;                    }                    else                    {                        result = int.Parse((pageRows * sc).ToString());                    }                    for (r = init; r < result; r++)                    {                        index = index + 1;                        for (int i = 0; i < columnNum; i++)                        {                            object obj = dtTmp.Rows[r][dtTmp.Columns[i].ToString()];                            datas[index, i] = obj == null ? "" : obj.ToString().Trim();                        }                    }                    Excel.Range fchR = worksheet.get_Range(worksheet.Cells[1, 1], worksheet.Cells[index + 1, columnNum]);                    fchR.Value2 = datas;                    worksheet.Columns.EntireColumn.AutoFit();   //列宽自适应。                    m_xlApp.WindowState = Excel.XlWindowState.xlMaximized;  //Sheet表最大化                    range = worksheet.get_Range(worksheet.Cells[1, 1], worksheet.Cells[index + 1, columnNum]);                    range.Font.Size = 9;                    range.RowHeight = 14.25;                    range.Borders.LineStyle = 1;                    range.HorizontalAlignment = 1;                }            }            else            {                string[,] datas = new string[rowNum + 1, columnNum];                for (int i = 0; i < columnNum; i++) //写入字段                {                    datas[0, i] = dtTmp.Columns[i].Caption;                }                Excel.Range range = worksheet.get_Range(worksheet.Cells[1, 1], worksheet.Cells[1, columnNum]);                range.Interior.ColorIndex = 15;     //15代表灰色                range.Font.Bold = true;                range.Font.Size = 9;                int r = 0;                for (r = 0; r < rowNum; r++)                {                    for (int i = 0; i < columnNum; i++)                    {                        object obj = dtTmp.Rows[r][dtTmp.Columns[i].ToString()];                        datas[r + 1, i] = obj == null ? "" : obj.ToString().Trim();                    }                }                Excel.Range fchR = worksheet.get_Range(worksheet.Cells[1, 1], worksheet.Cells[rowNum + 1, columnNum]);                fchR.Value2 = datas;                worksheet.Columns.EntireColumn.AutoFit();//列宽自适应。                m_xlApp.WindowState = Excel.XlWindowState.xlMaximized;                range = worksheet.get_Range(worksheet.Cells[1, 1], worksheet.Cells[rowNum + 1, columnNum]);                range.Font.Size = 9;                range.RowHeight = 14.25;                range.Borders.LineStyle = 1;                range.HorizontalAlignment = 1;            }            workbook.Saved = true;            workbook.SaveCopyAs(filePath);            lblMsg.Text = "导出成功！" + DateTime.Now.ToString();        }        catch (Exception ex)        {            string dd = Server.MapPath("~/Tmp/1.txt");            System.IO.File.AppendAllText(dd, "导出异常：" + ex.Message + Environment.NewLine);        }        finally        {            EndReport();        }    }    /// <summary>    /// 退出报表时关闭Excel和清理垃圾Excel进程    /// </summary>    private void EndReport()    {        object missing = System.Reflection.Missing.Value;        try        {            m_xlApp.Workbooks.Close();            m_xlApp.Workbooks.Application.Quit();            m_xlApp.Application.Quit();            m_xlApp.Quit();        }        catch        {        }        finally        {            try            {                System.Runtime.InteropServices.Marshal.ReleaseComObject(m_xlApp.Workbooks);                System.Runtime.InteropServices.Marshal.ReleaseComObject(m_xlApp.Application);                System.Runtime.InteropServices.Marshal.ReleaseComObject(m_xlApp);                m_xlApp = null;            }            catch            {            }            try            {                //清理垃圾进程                this.killProcessThread();            }            catch            {            }            GC.Collect();        }    }    /// <summary>    /// 杀掉不死进程    /// </summary>    private void killProcessThread()    {        ArrayList myProcess = new ArrayList();        for (int i = 0; i < myProcess.Count; i++)        {            try            {                System.Diagnostics.Process.GetProcessById(int.Parse((string)myProcess[i])).Kill();            }            catch            {            }        }    }

程序由原始的将数据一个表格一个表格地写入到EXCEL中，改变成程序先将数据存入二维数组中，然后再将数组值赋予EXCEL应用程序对象的VALUE属性，这样就使导出的效率提高很多，经测试导出100万以内的数据没问题。

更多.net技术详见：http://bbs.netluntan.com，群：121058751