//这里写了一个通用的类
using System;
using System.Data;
using System.Configuration;
using System.Collections.Generic;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
using System.Text;
using System.Reflection;
using System.IO;
using System.Data.Odbc;
namespace Com.DRPENG.SDXY.UI.Common
{
 public class CSVHelper
 {
  #region Fields
  string _fileName;
  DataTable _dataSource;//数据源
  string[] _titles = null;//列标题
  string[] _fields = null;//字段名
  #endregion
  #region .ctor
  /// <summary> 
  /// 构造函数 
  /// </summary> 
  /// <param name=\"dataSource\">数据源</param> 
  public CSVHelper()
  {
  }
  /// <summary> 
  /// 构造函数 
  /// </summary> 
  /// <param name=\"titles\">要输出到 Excel 的列标题的数组</param> 
  /// <param name=\"fields\">要输出到 Excel 的字段名称数组</param> 
  /// <param name=\"dataSource\">数据源</param> 
  public CSVHelper(string[] titles, string[] fields, DataTable dataSource)
   : this(titles, dataSource)
  {
   if (fields == null || fields.Length == 0)
    throw new ArgumentNullException(\"fields\");
   if (titles.Length != fields.Length)
    throw new ArgumentException(\"titles.Length != fields.Length\", \"fields\");
   _fields = fields;
  }
  /// <summary> 
  /// 构造函数 
  /// </summary> 
  /// <param name=\"titles\">要输出到 Excel 的列标题的数组</param> 
  /// <param name=\"dataSource\">数据源</param> 
  public CSVHelper(string[] titles, DataTable dataSource)
   : this(dataSource)
  {
   if (titles == null || titles.Length == 0)
    throw new ArgumentNullException(\"titles\");
   _titles = titles;
  }
  /// <summary> 
  /// 构造函数 
  /// </summary> 
  /// <param name=\"dataSource\">数据源</param> 
  public CSVHelper(DataTable dataSource)
  {
   if (dataSource == null)
    throw new ArgumentNullException(\"dataSource\");
   // maybe more checks needed here (IEnumerable, IList, IListSource, ) ??? 
   // 很难判断，先简单的使用 DataTable 
   _dataSource = dataSource;
  }
  #endregion
  #region public Methods
  #region 导出到CSV文件并且提示下载
  /// <summary>
  /// 导出到CSV文件并且提示下载
  /// </summary>
  /// <param name=\"fileName\"></param>
  public void DataToCSV(string fileName)
  {
   // 确保有一个合法的输出文件名 
   //if (fileName == null || fileName == string.Empty || !(fileName.ToLower().EndsWith(\".csv\")))
   // fileName = GetRandomFileName();
   string data = ExportCSV();
   HttpContext.Current.Response.ClearHeaders();
   HttpContext.Current.Response.Clear();
   HttpContext.Current.Response.Expires = 0;
   HttpContext.Current.Response.BufferOutput = true;
   HttpContext.Current.Response.Charset = \"GB2312\";
   HttpContext.Current.Response.ContentEncoding = System.Text.Encoding.GetEncoding(\"GB2312\");
   HttpContext.Current.Response.AppendHeader(\"Content-Disposition\", string.Format(\"attachment;filename={0}.csv\", System.Web.HttpUtility.UrlEncode(fileName, System.Text.Encoding.UTF8)));
   HttpContext.Current.Response.ContentType = \"text/h323;charset=gbk\";
   HttpContext.Current.Response.Write(data);
   HttpContext.Current.Response.End();
  }
  #endregion
  /// <summary>
  /// 获取CSV导入的数据
  /// </summary>
  /// <param name=\"filePath\">文件路径</param>
  /// <param name=\"fileName\">文件名称(.csv不用加)</param>
  /// <returns></returns>
  public DataTable GetCsvData(string filePath,string fileName)
  {
   string path = Path.Combine(filePath, fileName + \".csv\");
   string connString = @\"Driver={Microsoft Text Driver (*.txt; *.csv)};Dbq=\" + filePath + \";Extensions=asc,csv,tab,txt;\";
   try
   {
    using (OdbcConnection odbcConn = new OdbcConnection(connString))
    {
     odbcConn.Open();
     OdbcCommand oleComm = new OdbcCommand();
     oleComm.Connection = odbcConn;
     oleComm.CommandText = \"select * from [\" + fileName + \"#csv]\";
     OdbcDataAdapter adapter = new OdbcDataAdapter(oleComm);
     DataSet ds = new DataSet();
     adapter.Fill(ds, fileName);
     return ds.Tables[0];
     odbcConn.Close();
    }
    if (File.Exists(path))
    {
     File.Delete(path);
    }
   }
   catch (Exception ex)
   {
    if (File.Exists(path))
    {
     File.Delete(path);
    }
    throw ex;
   }
  }
  #endregion
  #region 返回写入CSV的字符串
  /// <summary>
  /// 返回写入CSV的字符串
  /// </summary>
  /// <returns></returns>
  private string ExportCSV()
  { 
   if(_dataSource==null)
    throw new ArgumentNullException(\"dataSource\");
   StringBuilder strbData = new StringBuilder();
   if (_titles == null)
   {
    //添加列名
    foreach (DataColumn column in _dataSource.Columns)
    {
     strbData.Append(column.ColumnName + \",\");
    }
    strbData.Append(\"\\n\");
    foreach (DataRow dr in _dataSource.Rows)
    {
     for (int i = 0; i < _dataSource.Columns.Count; i++)
     {
      strbData.Append(dr[i].ToString() + \",\");
     }
     strbData.Append(\"\\n\");
    }
    return strbData.ToString();
   }
   else
   {
    foreach (string columnName in _titles)
    {
     strbData.Append(columnName + \",\");
    }
    strbData.Append(\"\\n\");
    if (_fields == null)
    {
     foreach (DataRow dr in _dataSource.Rows)
     {
      for (int i = 0; i < _dataSource.Columns.Count; i++)
      {
       strbData.Append(dr[i].ToString() + \",\");
      }
      strbData.Append(\"\\n\");
     }
     return strbData.ToString();
    }
    else
    {
     foreach (DataRow dr in _dataSource.Rows)
     {
      for (int i = 0; i < _fields.Length; i++)
      {
       strbData.Append(_fields[i].ToString() + \",\");
      }
      strbData.Append(\"\\n\");
     }
     return strbData.ToString();
    }
   }
  }
  #endregion
  #region 得到一个随意的文件名
  /// <summary> 
  /// 得到一个随意的文件名 
  /// </summary> 
  /// <returns></returns> 
  private string GetRandomFileName()
  {
   Random rnd = new Random((int)(DateTime.Now.Ticks));
   string s = rnd.Next(Int32.MaxValue).ToString();
   return DateTime.Now.ToShortDateString() + \"_\" + s + \".csv\";
  }
  #endregion
 }
}