法一:加入特殊字符:
如,在身份证号码前后加入中括号,示例:[170621198310974682]
法二:在单元格中加入样式
Str="<table border=1><tr><td align='center' height='100' vlign='center' style="vnd.ms-excel.numberformat:@">999999999999999999999999999</td>
关于法二具体示例,可以参考:http://dotnet.aspx.cc/article/8a4cbf47-b888-4832-3389-ed3a3a3c8aab/read.aspx
在我们把DataGrid上的数据导入到Excel的时候，如果遇到比较长的数字字符串，比如身份证号码，就会在Excel里当成数字看待，并转换成科学计数法的格式，造成数据的丢失，下面这个方法就解决了这个问题，并示例如何进行其它的格式化。
OutPutExcel.aspx
Code<%@ Page language="c#" Codebehind="OutPutExcel.aspx.cs"
AutoEventWireup="false" Inherits="eMeng.Exam.OutPutExcel" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
<HTML>
<HEAD>
<title>OutPutExcel</title>
</HEAD>
<body>
<form id="Form1" method="post" runat="server">
<asp:DataGrid id="DataGrid1" runat="server"></asp:DataGrid>
<asp:Button id="Button1" runat="server" Text="输出到Excel"></asp:Button>
</form>
</body>
</HTML>
OutPutExcel.aspx.cs
Code
using System;using System.Collections;using System.ComponentModel;using System.Data;using System.Drawing;using System.Web;using System.Web.SessionState;using System.Web.UI;using System.Web.UI.WebControls;using System.Web.UI.HtmlControls;namespace eMeng.Exam
{
/**//// <summary>
/// OutPutExcel 的摘要说明。
/// </summary>public class OutPutExcel : System.Web.UI.Page{protected System.Web.UI.WebControls.Button Button1;protected System.Web.UI.WebControls.DataGrid DataGrid1;private void Page_Load(object sender, System.EventArgs e){// 在此处放置用户代码以初始化页面DataGrid1.DataSource=CreateDataSource();DataGrid1.DataBind();}/**//// <summary>/// 创建数据源/// </summary>/// <returns>DataView</returns>ICollection CreateDataSource() {DataTable dt = new DataTable();DataRow dr;dt.Columns.Add(new DataColumn("身份证号码", typeof(string)));dt.Columns.Add(new DataColumn("图书单价",typeof(decimal)));dt.Columns.Add(new DataColumn("购买数量",typeof(Int32)));dt.Columns.Add(new DataColumn("总价格",typeof(decimal)));for (int i = 0; i < 30; i++) {dr = dt.NewRow();dr[0] = "123456789123456789";dr[1] = 100 * i /3.0;dr[2] = i + 5;dr[3] = (decimal)dr[1] * (Int32)dr[2]; dt.Rows.Add(dr);}DataView dv = new DataView(dt);return dv;}/**//// <summary>/// 输出到Excel/// </summary>/// <param name="sender"></param>/// <param name="e"></param>private void Button1_Click(object sender, System.EventArgs e){Response.Clear(); Response.Buffer= true; Response.Charset="GB2312"; Response.AppendHeader("Content-Disposition","attachment;filename=FileName.xls"); Response.ContentEncoding=System.Text.Encoding.GetEncoding("GB2312");//设置输出流为简体中文Response.ContentType = "application/ms-excel";//设置输出文件类型为excel文件。 this.EnableViewState = false; System.Globalization.CultureInfo myCItrad = new System.Globalization.CultureInfo("ZH-CN",true);System.IO.StringWriter oStringWriter = new System.IO.StringWriter(myCItrad); System.Web.UI.HtmlTextWriter oHtmlTextWriter = new System.Web.UI.HtmlTextWriter(oStringWriter);this.DataGrid1.RenderControl(oHtmlTextWriter); Response.Write(oStringWriter.ToString());Response.End();}Web 窗体设计器生成的代码#region Web 窗体设计器生成的代码override protected void OnInit(EventArgs e){//// CODEGEN: 该调用是 ASP.NET Web 窗体设计器所必需的。//InitializeComponent();base.OnInit(e);}/**//// <summary>/// 设计器支持所需的方法 - 不要使用代码编辑器修改/// 此方法的内容。/// </summary>private void InitializeComponent(){ this.Button1.Click += new System.EventHandler(this.Button1_Click);this.DataGrid1.ItemDataBound += new System.Web.UI.WebControls.DataGridItemEventHandler(this.DataGrid1_ItemDataBound);this.Load += new System.EventHandler(this.Page_Load);}#endregionprivate void DataGrid1_ItemDataBound(object sender, System.Web.UI.WebControls.DataGridItemEventArgs e){if(e.Item.ItemType == ListItemType.Item || e.Item.ItemType == ListItemType.AlternatingItem){e.Item.Cells[0].Attributes.Add("style","vnd.ms-excel.numberformat:@");e.Item.Cells[3].Attributes.Add("style","vnd.ms-excel.numberformat:￥#,###.00");}}}
}