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  • C#读取Excel几种方法的体会

    (1) OleDb: 用这种方法读取Excel速度还是非常的快的,但这种方式读取数据的时候不太灵活,不过可以在 DataTable 中对数据进行一些删减修改

    这种方式将Excel作为一个数据源,直接用Sql语句获取数据了。所以读取之前要知道此次要读取的Sheet(当然也可以用序号,类似dt.Row[0][0]。这样倒是不需要知道Sheet)

    if (fileType == ".xls")
       connStr = "Provider=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + fileName + ";" + ";Extended Properties="Excel 8.0;HDR=YES;IMEX=1"";
    else
       connStr = "Provider=Microsoft.ACE.OLEDB.12.0;" + "Data Source=" + fileName + ";" + ";Extended Properties="Excel 12.0;HDR=YES;IMEX=1"";
      
    OleDbConnection conn new OleDbConnection(connStr);
    DataTable dtSheetName = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new object[] { null, null, null, "TABLE" });

    以上是读取Excel的Sheet名,xls和xlsx的连接字符串也不一样的,可以根据文件的后缀来区别。这里需要注意的一点,Excel里面只有一个Sheet,但通过这种方式读取Sheet可能会大于一个。原因已经有人在别的网站说过了,偷一下懒O(∩_∩)O,下面文段来自【cdwolfling

    【在使用过程中发现取出的Sheet和实际excel不一致, 会多出不少。目前总结后有两种情况:

    1. 取出的名称中,包括了XL命名管理器中的名称(参见XL2007的公式--命名管理器, 快捷键Crtl+F3);

    2. 取出的名称中,包括了FilterDatabase后缀的, 这是XL用来记录Filter范围的, 参见http://www.mrexcel.com/forum/showthread.php?t=27225

    对于第一点比较简单, 删除已有命名管理器中的内容即可;第二点处理起来比较麻烦, Filter删除后这些名称依然保留着,简单的做法是新增sheet然后将原sheet Copy进去】

    ---------------------------------

    但实际情况并不能为每个Excel做以上检查,【cdwolfling】也给出了过滤的方案,当时还是有点问题,本来补充了一点。总之先看代码吧

    for (int i = 0; i < dtSheetName.Rows.Count; i++)

    {

    SheetName = (string)dtSheetName.Rows[i]["TABLE_NAME"];
      
    if (SheetName .Contains("$") && !SheetName .Replace("'", "").EndsWith("$"))continue;//过滤无效SheetName完毕....

    da.SelectCommand = new OleDbCommand(String.Format(sql_F, tblName), conn);
    DataSet dsItem = new DataSet();
    da.Fill(dsItem, tblName);

    }

    因为读取出来无效SheetName一般情况最后一个字符都不会是$。如果SheetName有一些特殊符号,读取出来的SheetName会自动加上单引号,比如在Excel中将SheetName编辑成:MySheet(1),此时读取出来的SheetName就为:'MySheet(1)$',所以判断最后一个字符是不是$之前最好过滤一下单引号。

    优点:读取方式简单、读取速度快

    缺点:除了读取过程不太灵活之外,这种读取方式还有个弊端就是,当Excel数据量很大时。会非常占用内存,当内存不够时会抛出内存溢出的异常。

    不过一般情况下还是非常不错的

     读取Excel完整代码:

    /// <summary>
            /// 读取Excel文件到DataSet中
            /// </summary>
            /// <param name="filePath">文件路径</param>
            /// <returns></returns>
            public static DataSet ToDataTable(string filePath)
            {
                string connStr = "";            
                string fileType = System.IO.Path.GetExtension(fileName);
                if (string.IsNullOrEmpty(fileType)) return null;
      
                if (fileType == ".xls")
                    connStr = "Provider=Microsoft.Jet.OLEDB.4.0;" + "Data Source=" + filePath+ ";" + ";Extended Properties="Excel 8.0;HDR=YES;IMEX=1"";
                else
                    connStr = "Provider=Microsoft.ACE.OLEDB.12.0;" + "Data Source=" + filePath+ ";" + ";Extended Properties="Excel 12.0;HDR=YES;IMEX=1"";
                string sql_F = "Select * FROM [{0}]";
      
                OleDbConnection conn = null;
                OleDbDataAdapter da = null;
                DataTable dtSheetName= null;
      
                DataSet ds = new DataSet();
                try
                {
                    // 初始化连接,并打开
                    conn = new OleDbConnection(connStr);
                    conn.Open();
      
                    // 获取数据源的表定义元数据                        
                    string SheetName = "";
                    dtSheetName= conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new object[] { null, null, null, "TABLE" });
      
                    // 初始化适配器
                    da = new OleDbDataAdapter();
                    for (int i = 0; i < dtSheetName.Rows.Count; i++)
                    {
                        SheetName = (string)dtSheetName.Rows[i]["TABLE_NAME"];
      
                        if (SheetName .Contains("$") && !SheetName .Replace("'", "").EndsWith("$"))
                        {
                            continue;
                        }
      
                        da.SelectCommand = new OleDbCommand(String.Format(sql_F, SheetName ), conn);
                        DataSet dsItem = new DataSet();
                        da.Fill(dsItem, tblName);
      
                        ds.Tables.Add(dsItem.Tables[0].Copy());
                    }
                }
                catch (Exception ex)
                {
                }
                finally
                {
                    // 关闭连接
                    if (conn.State == ConnectionState.Open)
                    {
                        conn.Close();
                        da.Dispose();
                        conn.Dispose();
                    }
                }
                return ds;
            }

      

    (2):Com组件的方式读取Excel

    这种方式需要先引用 Microsoft.Office.Interop.Excel 。首选说下这种方式的优缺点

    优点:可以非常灵活的读取Excel中的数据

    缺点:如果是Web站点部署在IIS上时,还需要服务器机子已安装了Excel,有时候还需要为配置IIS权限。最重要的一点因为是基于单元格方式读取的,所以数据很慢(曾做过试验,直接读取千行、200多列的文件,直接读取耗时15分钟。即使采用多线程分段读取来提高CPU的利用率也需要8分钟。PS:CPU I3)

    需要读取大文件的的童鞋们慎重。。。

    附上单线程和多线程读取类:

      

    (3)NPOI方式读取Excel,NPOI是一组开源的组件,类似Java的 POI。包括:NPOI、NPOI.HPSF、NPOI.HSSF、NPOI.HSSF.UserModel、NPOI.POIFS、NPOI.Util,下载的时候别只下一个噢

    优点:读取Excel速度较快,读取方式操作灵活性

    缺点:只支持03的Excel,xlsx的无法读取。由于这点,使用这种方式的人不多啊,没理由要求客户使用03版Excel吧,再说03版Excel对于行数还有限制,只支持65536行。

    (听他们的开发人员说会在2012年底推出新版,支持xlsx的读取。但一直很忙没时间去关注这个事情,有兴趣的同学可以瞧瞧去)

    NPOI读取Excel类:

    using System;
    using System.Data;
    using System.IO;
    using System.Web;
    using NPOI;
    using NPOI.HPSF;
    using NPOI.HSSF;
    using NPOI.HSSF.UserModel;
    using NPOI.POIFS;
    using NPOI.Util;
    using System.Text;
    using System.Configuration;
      
    public class NPOIHelper
    {
        private static int ExcelMaxRow = Convert.ToInt32(ConfigurationManager.AppSettings["ExcelMaxRow"]);
        /// <summary>
        /// 由DataSet导出Excel
        /// </summary>
        /// <param name="sourceTable">要导出数据的DataTable</param>    
        /// <param name="sheetName">工作表名称</param>
        /// <returns>Excel工作表</returns>    
        private static Stream ExportDataSetToExcel(DataSet sourceDs)
        {
            HSSFWorkbook workbook = new HSSFWorkbook();
            MemoryStream ms = new MemoryStream();
      
            for (int i = 0; i < sourceDs.Tables.Count; i++)
            {
                HSSFSheet sheet = (HSSFSheet)workbook.CreateSheet(sourceDs.Tables[i].TableName);
                HSSFRow headerRow = (HSSFRow)sheet.CreateRow(0);
                // handling header.            
                foreach (DataColumn column in sourceDs.Tables[i].Columns)
                    headerRow.CreateCell(column.Ordinal).SetCellValue(column.ColumnName);
                // handling value.            
                int rowIndex = 1;
                foreach (DataRow row in sourceDs.Tables[i].Rows)
                {
                    HSSFRow dataRow = (HSSFRow)sheet.CreateRow(rowIndex);
                    foreach (DataColumn column in sourceDs.Tables[i].Columns)
                    {
                        dataRow.CreateCell(column.Ordinal).SetCellValue(row[column].ToString());
                    }
                    rowIndex++;
                }
            }
            workbook.Write(ms);
            ms.Flush();
            ms.Position = 0;
            workbook = null;
            return ms;
        }
        /// <summary>
        /// 由DataSet导出Excel
        /// </summary>   
        /// <param name="sourceTable">要导出数据的DataTable</param>
        /// <param name="fileName">指定Excel工作表名称</param>
        /// <returns>Excel工作表</returns>    
        public static void ExportDataSetToExcel(DataSet sourceDs, string fileName)
        {
            //检查是否有Table数量超过65325
            for (int t = 0; t < sourceDs.Tables.Count; t++)
            {
                if (sourceDs.Tables[t].Rows.Count > ExcelMaxRow)
                {
                    DataSet ds = GetdtGroup(sourceDs.Tables[t].Copy());
                    sourceDs.Tables.RemoveAt(t);
                    //将得到的ds插入 sourceDs中
                    for (int g = 0; g < ds.Tables.Count; g++)
                    {
                        DataTable dt = ds.Tables[g].Copy();
                        sourceDs.Tables.Add(dt);
                    }
                    t--;
                }
            }
      
            MemoryStream ms = ExportDataSetToExcel(sourceDs) as MemoryStream;
            HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + fileName);
            HttpContext.Current.Response.BinaryWrite(ms.ToArray());
            HttpContext.Current.ApplicationInstance.CompleteRequest();
            //HttpContext.Current.Response.End();
            ms.Close();
            ms = null;
        }
        /// <summary>
        /// 由DataTable导出Excel
        /// </summary>
        /// <param name="sourceTable">要导出数据的DataTable</param> 
        /// <returns>Excel工作表</returns>    
        private static Stream ExportDataTableToExcel(DataTable sourceTable)
        {
            HSSFWorkbook workbook = new HSSFWorkbook();
            MemoryStream ms = new MemoryStream();
            HSSFSheet sheet = (HSSFSheet)workbook.CreateSheet(sourceTable.TableName);
            HSSFRow headerRow = (HSSFRow)sheet.CreateRow(0);
            // handling header.      
            foreach (DataColumn column in sourceTable.Columns)
                headerRow.CreateCell(column.Ordinal).SetCellValue(column.ColumnName);
            // handling value.      
            int rowIndex = 1;
            foreach (DataRow row in sourceTable.Rows)
            {
                HSSFRow dataRow = (HSSFRow)sheet.CreateRow(rowIndex);
                foreach (DataColumn column in sourceTable.Columns)
                {
                    dataRow.CreateCell(column.Ordinal).SetCellValue(row[column].ToString());
                }
                rowIndex++;
            }
            workbook.Write(ms);
            ms.Flush();
            ms.Position = 0;
            sheet = null;
            headerRow = null;
            workbook = null;
            return ms;
        }
        /// <summary>
        /// 由DataTable导出Excel
        /// </summary>
        /// <param name="sourceTable">要导出数据的DataTable</param>
        /// <param name="fileName">指定Excel工作表名称</param>
        /// <returns>Excel工作表</returns>
        public static void ExportDataTableToExcel(DataTable sourceTable, string fileName)
        {
            //如数据超过65325则分成多个Table导出
            if (sourceTable.Rows.Count > ExcelMaxRow)
            {
                DataSet ds = GetdtGroup(sourceTable);
                //导出DataSet
                ExportDataSetToExcel(ds, fileName);
            }
            else
            {
                MemoryStream ms = ExportDataTableToExcel(sourceTable) as MemoryStream;
                HttpContext.Current.Response.AppendHeader("Content-Disposition", "attachment;filename=" + fileName);
                HttpContext.Current.Response.BinaryWrite(ms.ToArray());
                HttpContext.Current.ApplicationInstance.CompleteRequest();
                //HttpContext.Current.Response.End();
                ms.Close();
                ms = null;
            }
        }
      
        /// <summary>
        /// 传入行数超过65325的Table,返回DataSet
        /// </summary>
        /// <param name="dt"></param>
        /// <returns></returns>
        public static DataSet GetdtGroup(DataTable dt)
        {
            string tablename = dt.TableName;
      
            DataSet ds = new DataSet();
            ds.Tables.Add(dt);
      
            double n = dt.Rows.Count / Convert.ToDouble(ExcelMaxRow);
      
            //创建表
            for (int i = 1; i < n; i++)
            {
                DataTable dtAdd = dt.Clone();
                dtAdd.TableName = tablename + "_" + i.ToString();
                ds.Tables.Add(dtAdd);
            }
      
            //分解数据
            for (int i = 1; i < ds.Tables.Count; i++)
            {
                //新表行数达到最大 或 基表数量不足
                while (ds.Tables[i].Rows.Count != ExcelMaxRow && ds.Tables[0].Rows.Count != ExcelMaxRow)
                {
                    ds.Tables[i].Rows.Add(ds.Tables[0].Rows[ExcelMaxRow].ItemArray);
                    ds.Tables[0].Rows.RemoveAt(ExcelMaxRow);
      
                }
            }
      
            return ds;
        }
      
        /// <summary>
        /// 由DataTable导出Excel
        /// </summary>
        /// <param name="sourceTable">要导出数据的DataTable</param>
        /// <param name="fileName">指定Excel工作表名称</param>
        /// <returns>Excel工作表</returns>
        public static void ExportDataTableToExcelModel(DataTable sourceTable, string modelpath, string modelName, string fileName, string sheetName)
        {
            int rowIndex = 2;//从第二行开始,因为前两行是模板里面的内容 
            int colIndex = 0;
            FileStream file = new FileStream(modelpath + modelName + ".xls", FileMode.Open, FileAccess.Read);//读入excel模板
            HSSFWorkbook hssfworkbook = new HSSFWorkbook(file);
            HSSFSheet sheet1 = (HSSFSheet)hssfworkbook.GetSheet("Sheet1");
            sheet1.GetRow(0).GetCell(0).SetCellValue("excelTitle");      //设置表头
            foreach (DataRow row in sourceTable.Rows)
            {   //双循环写入sourceTable中的数据
                rowIndex++;
                colIndex = 0;
                HSSFRow xlsrow = (HSSFRow)sheet1.CreateRow(rowIndex);
                foreach (DataColumn col in sourceTable.Columns)
                {
                    xlsrow.CreateCell(colIndex).SetCellValue(row[col.ColumnName].ToString());
                    colIndex++;
                }
            }
            sheet1.ForceFormulaRecalculation = true;
            FileStream fileS = new FileStream(modelpath + fileName + ".xls", FileMode.Create);//保存
            hssfworkbook.Write(fileS);
            fileS.Close();
            file.Close();
        }
    }

      

    Config配置了 【ExcelMaxRow】值 65535

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  • 原文地址:https://www.cnblogs.com/cenyuxin/p/3367857.html
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