近日做一些用户数据的整合，需要将一些活动的用户数据导出到txt文件中，将页面的代码复制如下：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Data;
using System.IO;
using BLL;

public partial class ExportData : System.Web.UI.Page
{
    private const string txtPath = @"D:\data\txt";
    private const string txtPostFix = ".txt";
    private const int dataDistance = 5;
    private const int tabDistance = 8;

    protected void Page_Load(object sender, EventArgs e)
    {
        if (!IsPostBack)
        {
            if (Request.QueryString["activityId"] != null)
            {
                int activityId = Convert.ToInt32(Request.QueryString["activityId"].ToString());
                DataSet dsUsers = UsersManager.GetUsersByActivityID(activityId);
                ExportToTxt(dsUsers);
            }
        }

    }
    ///
    /// 把数据文件导入到.txt文件
    ///
    ///
    public void ExportToTxt(DataSet ds)
    {
        if (ds.Tables.Count != 0)
        {
            string tempFileName = null;
            tempFileName = GetTempFileName();

            //创建一个.txt文件，文件名用系统时间生成精确到毫秒
            FileInfo file = new FileInfo(txtPath + tempFileName + txtPostFix);
            StreamWriter textFile = null;
            try
            {
                textFile = file.CreateText();
            }
            catch
            {
                Response.Write("
                return;
            }
            //把Dataset中的数据写入.txt文件中
            for (int totaltable = 0; totaltable < ds.Tables.Count; totaltable++)
            {
                //统计dataset中当前表的行数
                int row = ds.Tables[totaltable].Rows.Count;
                //统计dataset中当前表的列数
                int column = ds.Tables[totaltable].Columns.Count;
                //用于统计当前表中每列记录中字符数最长的字符串的长度之和
                int totalLength = 0;
                //用于统计标题的长度（dataset中的表名的length+"表的数据如下"的length）
                int titleLength = 0;
                //统计每列记录中字符数最长的字符串的长度
                int[] columnLength = new int[column];
                for (int i = 0; i < column; i++)
                {
                    columnLength[i] = ds.Tables[totaltable].Columns[i].ColumnName.ToString().Length;
                }
                for (int i = 0; i < row; i++)
                {
                    for (int j = 0; j < column; j++)
                    {
                        if (ds.Tables[totaltable].Rows[i][j].ToString().Length > columnLength[j])
                        {
                            columnLength[j] = ds.Tables[totaltable].Rows[i][j].ToString().Length;
                        }
                    }
                }

                //统计当前表中每列记录中字符数最长的字符串的长度之和
                for (int i = 0; i < column; i++)
                {
                    totalLength = totalLength + columnLength[i] + dataDistance;
                }
                totalLength = totalLength + 2 * tabDistance - dataDistance;
                //统计标题的长度（dataset中的当前表名的length+"表的数据如下"的length）
                titleLength = ds.Tables[totaltable].TableName.ToString().Length + "表的数据如下".Length * 2;
                //把标题写入.txt文件中
                for (int i = 0; i < (int)((totalLength - titleLength) / 2); i++)
                {
                    textFile.Write(' ');
                }
                textFile.Write(ds.Tables[totaltable].TableName + "表的数据如下");
                textFile.WriteLine();
                for (int i = 0; i < totalLength; i++)
                {
                    textFile.Write('*');
                }
                textFile.WriteLine();
                textFile.Write("\t");
                //把dataset中当前表的字段名写入.txt文件中
                for (int i = 0; i < column; i++)
                {
                    textFile.Write(ds.Tables[totaltable].Columns[i].ColumnName.ToString());
                    for (int k = 0; k < columnLength[i] - ds.Tables[totaltable].Columns[i].ColumnName.ToString().Length + dataDistance; k++)
                    {
                        textFile.Write(' ');
                    }
                }
                textFile.WriteLine();
                for (int i = 0; i < totalLength; i++)
                {
                    textFile.Write('-');
                }
                textFile.WriteLine();
                textFile.Write("\t");
                //把dataset中当前表的数据写入.txt文件中
                for (int i = 0; i < row; i++)
                {
                    for (int j = 0; j < column; j++)
                    {
                        textFile.Write(ds.Tables[totaltable].Rows[i][j].ToString());
                        for (int k = 0; k < columnLength[j] - ds.Tables[totaltable].Rows[i][j].ToString().Length + dataDistance; k++)
                        {
                            textFile.Write(' ');
                        }
                    }
                    textFile.WriteLine();
                    textFile.Write("\t");
                }
                textFile.WriteLine();
                for (int i = 0; i < totalLength; i++)
                {
                    textFile.Write('-');
                }
                textFile.WriteLine();
                textFile.WriteLine();
                textFile.WriteLine();
            }
            //关闭当前的StreamWriter流
            textFile.Close();
            Response.Write("
        }
        else
        {
            Response.Write("
        }
    }
    public string GetTempFileName()
    {
        return DateTime.Now.ToString("yyyyMMddhhmmssfff");
    }
}

参考百度文库：http://wenku.baidu.com/view/247de6d3360cba1aa811da16.html