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C#读取Excel几种方法的体会

原作者: [db:作者] 来自: [db:来源] 收藏 邀请

(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:

public class ExcelOptions
    {
        private Stopwatch wath = new Stopwatch();
 
        /// <summary>
        /// 使用COM读取Excel
        /// </summary>
        /// <param name="excelFilePath">路径</param>
        /// <returns>DataTabel</returns>
        public System.Data.DataTable GetExcelData(string excelFilePath)
        {
            Excel.Application app = new Excel.Application();
            Excel.Sheets sheets;
            Excel.Workbook workbook = null;
            object oMissiong = System.Reflection.Missing.Value;
            System.Data.DataTable dt = new System.Data.DataTable();
 
            wath.Start();
 
            try
            {
                if (app == null)
                {
                    return null;
                }
 
                workbook = app.Workbooks.Open(excelFilePath, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong);
 
                //将数据读入到DataTable中——Start  
 
                sheets = workbook.Worksheets;
                Excel.Worksheet worksheet = (Excel.Worksheet)sheets.get_Item(1);//读取第一张表
                if (worksheet == null)
                    return null;
 
                string cellContent;
                int iRowCount = worksheet.UsedRange.Rows.Count;
                int iColCount = worksheet.UsedRange.Columns.Count;
                Excel.Range range;
 
                //负责列头Start
                DataColumn dc;
                int ColumnID = 1;
                range = (Excel.Range)worksheet.Cells[1, 1];
                while (range.Text.ToString().Trim() != "")
                {
                    dc = new DataColumn();
                    dc.DataType = System.Type.GetType("System.String");
                    dc.ColumnName = range.Text.ToString().Trim();
                    dt.Columns.Add(dc);
 
                    range = (Excel.Range)worksheet.Cells[1, ++ColumnID];
                }
                //End
 
                for (int iRow = 2; iRow <= iRowCount; iRow++)
                {
                    DataRow dr = dt.NewRow();
 
                    for (int iCol = 1; iCol <= iColCount; iCol++)
                    {
                        range = (Excel.Range)worksheet.Cells[iRow, iCol];
 
                        cellContent = (range.Value2 == null) ? "" : range.Text.ToString();
 
                        //if (iRow == 1)
                        //{
                        //    dt.Columns.Add(cellContent);
                        //}
                        //else
                        //{
                            dr[iCol - 1] = cellContent;
                        //}
                    }
 
                    //if (iRow != 1)
                    dt.Rows.Add(dr);
                }
 
                wath.Stop();
                TimeSpan ts = wath.Elapsed;
 
                //将数据读入到DataTable中——End
                return dt;
            }
            catch
            {
                 
                return null;
            }
            finally
            {
                workbook.Close(false, oMissiong, oMissiong);
                System.Runtime.InteropServices.Marshal.ReleaseComObject(workbook);
                workbook = null;
                app.Workbooks.Close();
                app.Quit();
                System.Runtime.InteropServices.Marshal.ReleaseComObject(app);
                app = null;
                GC.Collect();
                GC.WaitForPendingFinalizers();
            }
        }
 
 
        /// <summary>
        /// 使用COM,多线程读取Excel(1 主线程、4 副线程)
        /// </summary>
        /// <param name="excelFilePath">路径</param>
        /// <returns>DataTabel</returns>
        public System.Data.DataTable ThreadReadExcel(string excelFilePath)
        {
            Excel.Application app = new Excel.Application();
            Excel.Sheets sheets = null;
            Excel.Workbook workbook = null;
            object oMissiong = System.Reflection.Missing.Value;
            System.Data.DataTable dt = new System.Data.DataTable();
 
            wath.Start();
 
            try
            {
                if (app == null)
                {
                    return null;
                }
 
                workbook = app.Workbooks.Open(excelFilePath, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong, oMissiong);
 
                //将数据读入到DataTable中——Start  
                sheets = workbook.Worksheets;
                Excel.Worksheet worksheet = (Excel.Worksheet)sheets.get_Item(1);//读取第一张表
                if (worksheet == null)
                    return null;
 
                string cellContent;
                int iRowCount = worksheet.UsedRange.Rows.Count;
                int iColCount = worksheet.UsedRange.Columns.Count;
                Excel.Range range;
 
                //负责列头Start
                DataColumn dc;
                int ColumnID = 1;
                range = (Excel.Range)worksheet.Cells[1, 1];
                //while (range.Text.ToString().Trim() != "")
                while (iColCount >= ColumnID)
                {
                    dc = new DataColumn();
                    dc.DataType = System.Type.GetType("System.String");
 
                    string strNewColumnName = range.Text.ToString().Trim();
                    if (strNewColumnName.Length == 0) strNewColumnName = "_1";
                    //判断列名是否重复
                    for (int i = 1; i < ColumnID; i++)
                    {
                        if (dt.Columns[i - 1].ColumnName == strNewColumnName)
                            strNewColumnName = strNewColumnName + "_1";
                    }
 
                    dc.ColumnName = strNewColumnName;
                    dt.Columns.Add(dc);
 
                    range = (Excel.Range)worksheet.Cells[1, ++ColumnID];
                }
                //End
 
                //数据大于500条,使用多进程进行读取数据
                if (iRowCount - 1 > 500)
                {
                    //开始多线程读取数据
                    //新建线程
                    int b2 = (iRowCount - 1) / 10;
                    DataTable dt1 = new DataTable("dt1");
                    dt1 = dt.Clone();
                    SheetOptions sheet1thread = new SheetOptions(worksheet, iColCount, 2, b2 + 1, dt1);
                    Thread othread1 = new Thread(new ThreadStart(sheet1thread.SheetToDataTable));
                    othread1.Start();
 
                    //阻塞 1 毫秒,保证第一个读取 dt1
                    Thread.Sleep(1);
 
                    DataTable dt2 = new DataTable("dt2");
                    dt2 = dt.Clone();
                    SheetOptions sheet2thread = new SheetOptions(worksheet, iColCount, b2 + 2, b2 * 2 + 1, dt2);
                    Thread othread2 = new Thread(new ThreadStart(sheet2thread.SheetToDataTable));
                    othread2.Start();
 
                    DataTable dt3 = new DataTable("dt3");
                    dt3 = dt.Clone();
                    SheetOptions sheet3thread = new SheetOptions(worksheet, iColCount, b2 * 2 + 2, b2 * 3 + 1, dt3);
                    Thread othread3 = new Thread(new ThreadStart(sheet3thread.SheetToDataTable));
                    othread3.Start();
 
                    DataTable dt4 = new DataTable("dt4");
                    dt4 = dt.Clone();
                    SheetOptions sheet4thread = new SheetOptions(worksheet, iColCount, b2 * 3 + 2, b2 * 4 + 1, dt4);
                    Thread othread4 = new Thread(new ThreadStart(sheet4thread.SheetToDataTable));
                    othread4.Start();
 
                    //主线程读取剩余数据
                    for (int iRow = b2 * 4 + 2; iRow <= iRowCount; iRow++)
                    {
                        DataRow dr = dt.NewRow();
                        for (int iCol = 1; iCol <= iColCount; iCol++)
                        {
                            range = (Excel.Range)worksheet.Cells[iRow, iCol];
                            cellContent = (range.Value2 == null) ? "" : range.Text.ToString();
                            dr[iCol - 1] = cellContent;
                        }
                        dt.Rows.Add(dr);
                    }
 
                    othread1.Join();
                    othread2.Join();
                    othread3.Join();
                    othread4.Join();
 
                    //将多个线程读取出来的数据追加至 dt1 后面
                    foreach (DataRow dr in dt.Rows)
                        dt1.Rows.Add(dr.ItemArray);
                    dt.Clear();
                    dt.Dispose();
 
                    foreach (DataRow dr in dt2.Rows)
                        dt1.Rows.Add(dr.ItemArray);
                    dt2.Clear();
                    dt2.Dispose();
 
                    foreach (DataRow dr in dt3.Rows)
                        dt1.Rows.Add(dr.ItemArray);
                    dt3.Clear();
                    dt3.Dispose();
 
                    foreach (DataRow dr in dt4.Rows)
                        dt1.Rows.Add(dr.ItemArray);
                    dt4.Clear();
                    dt4.Dispose();
 
         

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