C#大量数据导出到Excel(转)

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
            {
            }
        }
    }