C#中 导入和导出Excel的方法

 using System.Data;
 using System.Data.OleDb;
 /// <summary>
 /// Excel转为DataTable
 /// </summary>
 /// <param name="ExcelName"></param>
 /// <returns></returns>
 public static DataTable ExcelToDataTable(string filePath)
 {
     string strCon = "Provider = Microsoft.ACE.OLEDB.12.0 ;Data Source=" + filePath + ";Extended Properties='Excel 12.0;HDR=YES;'";// IMEX=1为导入模式
     OleDbConnection olecon = new OleDbConnection(strCon);
     olecon.Open();
     DataTable dt = olecon.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new Object[] { null, null, null, "TABLE" });
     ]["TABLE_NAME"].ToString();//获取Excel表名
     OleDbDataAdapter myda = new OleDbDataAdapter("SELECT * FROM [" + sheetName + "]", strCon);
     DataTable mydt = new DataTable();
     myda.Fill(mydt);
     olecon.Close();
     return mydt;
 }

 /// <summary>
 /// DataTable导出Excel
 /// GridView作为中间数据格式转换用途
 /// </summary>
 /// <param name="page">Page对象</param>
 /// <param name="columns">导出数据源</param>
 /// <param name="dt">导出显示列与对应数据列，Key:Excel列名，Value:数据源列名</param>
 /// <param name="fileName">导出文件名，无需带后缀</param>
 public static void GridViewToExcel(Page page, DataTable dt, Dictionary<string, string> columns, string fileName)
 {
      || columns == )
     {
         return;
     }

     if (string.IsNullOrEmpty(fileName.Trim()))
     {
         fileName = "DataToExcel";
     }

     DataTable temp = new DataTable();

     foreach (KeyValuePair<string, string> item in columns)
     {
         temp.Columns.Add(item.Key);
     }

     foreach (DataRow dr in dt.Rows)
     {
         DataRow drs = temp.NewRow();

         foreach (KeyValuePair<string, string> item in columns)
         {
             drs[item.Key] = dr[item.Value];
         }
         temp.Rows.Add(drs);
     }

     GridView gv = new GridView();
     gv.DataSource = temp;
     gv.AllowPaging = false;
     gv.EnableViewState = false;
     gv.DataBind();

     StringWriter strWriter = new StringWriter();
     HtmlTextWriter htmlWriter = new HtmlTextWriter(strWriter);

     page.Response.Clear();
     page.Response.Buffer = true;
     page.Response.Charset = "GB2312";
     page.Response.HeaderEncoding = System.Text.Encoding.GetEncoding("GB2312");
     page.Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
     page.Response.AppendHeader("Content-Disposition", "attachment;filename=" + fileName + ".xls");
     page.Response.ContentType = "application/ms-excel";
     gv.RenderControl(htmlWriter);
     page.Response.Write(strWriter.ToString());
     page.Response.End();
 }

 /// <summary>
 /// DataTable导出Excel，自定义Html Table格式
 /// </summary>
 /// <param name="page">Page对象</param>
 /// <param name="dt">DataTable</param>
 /// <param name="columns">导出显示列与对应数据列，Key:Excel导出列名，Value:数据源列名</param>
 /// <param name="fileName">导出文件名，无需带后缀</param>
 public static void ToExcel(Page page, DataTable dt1, Dictionary<string, string> columns, string fileName)
 {

      || columns == )
     {
         return;
     }

     if (string.IsNullOrEmpty(fileName.Trim()))
     {
         fileName = "DataToExcel";
     }
     page.Response.Clear();
     page.Response.Buffer = true;
     page.Response.Charset = "GB2312";
     page.Response.HeaderEncoding = System.Text.Encoding.GetEncoding("GB2312");
     page.Response.ContentEncoding = System.Text.Encoding.GetEncoding("GB2312");
     page.Response.ContentType = "application/ms-excel";
     page.Response.AppendHeader("Content-Disposition", "attachment;filename=" + fileName + ".xls");

     System.Text.StringBuilder builder = new System.Text.StringBuilder();
     builder.Append("<html xmlns:x=\"urn><head>\n");
     builder.Append("<meta http-equiv=\"Content-Language\" content=\"zh-cn\"><meta http-equiv=\"Content-Type\" content=\"text/html;charset=gb2312\"></head>");
     builder.Append("<table border=1 style=\"vnd.ms-excel.numberformat:@\"><tr>");

     foreach (KeyValuePair<string, string> item in columns)
     {
         builder.Append("<th>" + item.Key + "</th>");
     }

     builder.Append("</tr>");

     foreach (DataRow item in dt1.Rows)
     {
         builder.Append("<tr>");
         foreach (KeyValuePair<string, string> kv in columns)
         {
             if (IsDateTime(item[kv.Value].ToString()))
                 builder.Append("<td style=\"vnd.ms-excel.numberformat:yyyy-MM-dd\">" + item[kv.Value] + "</td>");
             else
                 builder.Append("<td>" + item[kv.Value] + "</td>");
         }
         builder.Append("</tr>");
     }
     builder.Append("</table>");
     page.Response.Write(builder.ToString());
     page.Response.Flush();
     page.Response.End();
 }