DataTable To Excel

using System;
using System.Collections;
using System.Configuration;
using System.Data;
using System.Linq;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.HtmlControls;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Xml.Linq;
using System.IO;
using Microsoft.Office.Interop.Excel;
using System.Data.SqlClient;

public  partial  class Excel : System.Web.UI.Page
{
    SQLHelper sqlH;
     protected  void Page_Load( object sender, EventArgs e)
    {
      
    }
     protected  void BtnExport_Click( object sender, EventArgs e)
    {
         string str =  " SELECT [classID],[className] FROM [SchoolNews].[dbo].[newsClass]  ";
         string excelName =  " KQ ";
         string createTime = DateTime.Now.ToString( " yyyyMMdd ");
        Export(str,excelName);
    }
     protected  void Export( string str, string excelName)
    {
         //  sqlH = new SQLHelper();

         // string str = "SELECT [classID],[className] FROM [SchoolNews].[dbo].[newsClass] ";
        SqlConnection sqlCon =  new SqlConnection( " server=.;database=schoolnews;uid=sa;pwd=; ");
        sqlCon.Open();
        SqlCommand sqlcom =  new SqlCommand(str, sqlCon);
        System.Data.SqlClient.SqlDataReader sdr = sqlcom.ExecuteReader();
        System.Data.DataTable dt =  new System.Data.DataTable();
        dt.Load(sdr);
        sdr.Close();
        sqlCon.Close();

         int[] index = {  0,  1 };
         string[] heads = {  " classID ",  " className " };
         // string name = Server.MapPath("file/template.xls");
         string name =  " C:\\excel\\ "+excelName+ " .xlsx ";
        ExportToExcel(dt,  " C:\\excel\\ " + excelName +  " .xlsx ", index, heads); //  Server.MapPath("file/template.xls")
        System.IO.FileInfo aFile =  new System.IO.FileInfo(name);
         string na = Path.GetFileName(name);
        Response.Clear();
        Response.ClearHeaders();
        Response.BufferOutput =  false;
        Response.ContentType =  " application/ms-excel ";
         // Response.AddHeader("Content-Disposition","attachment;filename="+na);  
         // 上面这条中文会乱码,应该下面这样写  
        Response.AppendHeader( " Content-disposition ",  " attachment;filename= " + HttpUtility.UrlEncode(na, System.Text.Encoding.UTF8));
        Response.AddHeader( " Content-Length ", aFile.Length.ToString());
        Response.WriteFile(name);
        Response.Flush();
        Response.End();
    }
     public  static  bool ExportToExcel(System.Data.DataTable table,  string excelName,  int[] columnIndexs,  string[] columnHeads)
    {
         #region 将方法中用到的所有Excel变量声明在方法最开始，以便最后统一回收。
         object missing = System.Reflection.Missing.Value;

        Microsoft.Office.Interop.Excel.ApplicationClass oExcel =  new Microsoft.Office.Interop.Excel.ApplicationClass();
        Microsoft.Office.Interop.Excel.Workbook obook =  null;
        Microsoft.Office.Interop.Excel.Worksheet oSheet =  null;
        Microsoft.Office.Interop.Excel.Range range =  null;
         #endregion
         try
        {
            obook = oExcel.Workbooks.Add( "");

            oSheet = (Microsoft.Office.Interop.Excel.Worksheet)obook.Worksheets[ 1];
             int rCount, cCount;
            rCount = table.Rows.Count;
            cCount = table.Columns.Count;
             object obj = System.Reflection.Missing.Value;

             if (cCount < columnIndexs.Length || cCount < columnHeads.Length)
            {
                 throw  new ArgumentOutOfRangeException( " columnIndexs 与 columnHeads 长度必须一致。 ");
            }
             for ( int i =  1; i <= columnIndexs.Length; i++)
            {
                 // Excel.Range = (Excel.Range)oSheet.Columns.get_Item(i, obj); 
                range = (Microsoft.Office.Interop.Excel.Range)oSheet.Columns.get_Item(i, obj);
                range.NumberFormatLocal =  " @ ";
            }
             for ( int c =  0; c < columnIndexs.Length; c++)
            {
                oSheet.Cells[ 1, c +  1] = columnHeads[c];
                 for ( int r =  1; r <= rCount; r++)
                {
                    oSheet.Cells[r +  1, c +  1] = table.Rows[r -  1][columnIndexs[c]].ToString();
                }
            }
            obook.Saved =  true;
            obook.SaveCopyAs(excelName);

             // 必须调用 obook.Close()， 否则无法释放进程。
            obook.Close( false, System.Reflection.Missing.Value, System.Reflection.Missing.Value);
             return  true;
        }
         catch (Exception ex)
        {
             throw ex;
        }
         finally
        {
             //  调用System.Runtime.InteropServices.Marshal.ReleaseComObject（object）方法释放方法中
             // 用到的所有的Excel 变量， 记住是所有的。 比如说此方法中的range 对象， 就容易被遗忘。

            System.Runtime.InteropServices.Marshal.ReleaseComObject(range);
            System.Runtime.InteropServices.Marshal.ReleaseComObject(oSheet);
            System.Runtime.InteropServices.Marshal.ReleaseComObject(obook);

             //  很多文章上都说必须调用此方法， 但是我试过没有调用oExcel.Quit() 的情况， 进程也能安全退出，
             // 还是保留着吧。
            oExcel.Quit();
            System.Runtime.InteropServices.Marshal.ReleaseComObject(oExcel);
             //  垃圾回收是必须的。 测试如果不执行垃圾回收， 无法关闭Excel 进程。
            GC.Collect();
        }
    }

}