datatable to csv

 

     ///   <summary>
     ///  DataTableToCsv
     ///   </summary>
     ///   <param name="dt"></param>
     ///   <param name="fileName"> 文件名称，不用后缀 </param>
     ///   <remarks>
     ///  文件格式
     /// 每条记录占一行 
     /// 以逗号为分隔符 
     /// 逗号前后的空格会被忽略 
     /// 字段中包含有逗号，该字段必须用双引号括起来 
     /// 字段中包含有换行符，该字段必须用双引号括起来 
     /// 字段前后包含有空格，该字段必须用双引号括起来 
     /// 字段中的双引号用两个双引号表示 
     /// 字段中如果有双引号，该字段必须用双引号括起来 
     /// 第一条记录，可以是字段名 
     ///   </remarks>
     public   static   void  DataTableToCsv(DataTable dt,  string  fileName)
    {
         // Clear <div  id="loading" ..
        HttpContext.Current.Response.Clear();

         #region  Export Grid to CSV
         //  Create the CSV file to which grid data will be exported.
        System.IO.StringWriter sw  =   new  System.IO.StringWriter();
         //  First we will write the headers.
         int  iColCount  =  dt.Columns.Count;
         for  ( int  i  =   0 ; i  <  iColCount; i ++ )
        {
            sw.Write( " \ ""  + dt.Columns[i] + " \ "" );
             if  (i  <  iColCount  -   1 )
            {
                sw.Write( " , " );
            }
        }
        sw.Write(sw.NewLine);
         //  Now write all the rows.
         foreach  (DataRow dr  in  dt.Rows)
        {
             for  ( int  i  =   0 ; i  <  iColCount; i ++ )
            {
                 if  ( ! Convert.IsDBNull(dr[i]))
                    sw.Write( " \ ""  + dr[i].ToString() +  " \ "" );
                 else
                    sw.Write( " \ " \ "" );

                 if  (i  <  iColCount  -   1 )
                {
                    sw.Write( " , " );
                }
            }
            sw.Write(sw.NewLine);
        }
        sw.Close();
         #endregion

        HttpContext.Current.Response.AddHeader( " Content-Disposition " ,  " attachment; filename= "   +  fileName  +   string .Format( " {0:yyyyMMddhhmmss} " , DateTime.Now)  +   " .csv " );
        HttpContext.Current.Response.ContentType  =   " application/vnd.ms-excel " ;
        HttpContext.Current.Response.ContentEncoding  =  System.Text.Encoding.GetEncoding( " GB2312 " );
        HttpContext.Current.Response.Write(sw);
        HttpContext.Current.Response.End();
    }

 

 

 

     ///   <summary>
     ///  该方法实现从Excel中导出数据到DataSet中，其中filepath为Excel文件的绝对路径，sheetname为表示那个Excel表；
     ///   </summary>
     ///   <param name="filepath"> filepath </param>
     ///   <param name="sheetname"> Sheet1 </param>
     ///   <returns></returns>
     public  DataSet ExcelDataSource(  string  filepath ,  string  sheetname )
    {
         string  strConn;
        strConn  =   " Provider=Microsoft.Jet.OLEDB.4.0;Data Source= "   +  filepath  +   " ;Extended Properties=Excel 8.0; " ;
        OleDbConnection conn  =   new  OleDbConnection(strConn);
        OleDbDataAdapter oada  =   new  OleDbDataAdapter (  " select * from [ "   +  sheetname  +   " $] " , strConn );
        DataSet ds  =   new  DataSet ();
        oada.Fill (ds);
         return  ds ;
    }