.NET中的CSV导入导出

        /// <summary>
        /// Get Data From Csv File 
        /// (Through StreamReader)
        /// </summary>
        /// <returns></returns>
        private bool GetData(Stream inputStream, out string errMessage, out DataTable dtFile)
        {
            errMessage = String.Empty;
            dtFile = new DataTable();


            //this.FileUploadImport.PostedFile.InputStream.CanSeek;
            //StreamReader sr = new StreamReader(this.FileUploadImport.PostedFile.InputStream); //update by hwx 11/12/2010
            StreamReader sr = new StreamReader(inputStream);
            int iColumnCount = 19;//the column count in the file
            int iRow = 1;// the row number is being read
            int iColumn = 0;// the column number is being read
            string strStandardTitle = string.Empty; // the title as it is

            //read title row
            string strTitle = sr.ReadLine();

            //string[] strRowTitle = strTitle.Split(new char[] { ',' });
            string[] strRowTitle = new string[iColumnCount];
            string strCharTitle;
            int iCellNumberTitle = 0;
            bool blnQuoteTitle = false;
            for (int i = 0; i < strTitle.Length; i++)
            {
                strCharTitle = strTitle.Substring(i, 1);
                if (strCharTitle == ",")// "," is the seperation symbol of csv file,
                {
                    if (!blnQuoteTitle)
                    {
                        iCellNumberTitle++;// out of the "" range, "," is the seperation symbol
                        if (iCellNumberTitle >= iColumnCount)// too many column in this line
                        {
                            break;
                        }
                    }
                    else
                    {
                        strRowTitle[iCellNumberTitle] += strCharTitle;
                    }
                }
                else if (strCharTitle == "\"")// "\"" is the transfer symbol of csv file,
                {
                    blnQuoteTitle = !blnQuoteTitle;
                    if (blnQuoteTitle && i > 0 && strTitle.Substring(i - 1, 1) == "\"")//in the "" range and there is an transfer symbol before
                    {
                        strRowTitle[iCellNumberTitle] += strCharTitle;
                    }
                }
                else
                {
                    strRowTitle[iCellNumberTitle] += strCharTitle;
                }
            }
            //read the content
            if (strRowTitle.Length == iColumnCount)
            {
                foreach (string strCell in strRowTitle)
                {
                    iColumn++;
                    if (strCell.Trim() != string.Empty)
                    {
                        dtFile.Columns.Add(strCell);//add new column with name to the data table

                    }
                    else //file error:blank title
                    {

                        errMessage += "The cell " + iColumn.ToString() + " is blank in the header row.\r\n";
                    }
                }
                if (dtFile.Columns.Count == iColumnCount)//make sure that no blank header or error header
                {
                    //read content row
                    string strLine;
                    while (!sr.EndOfStream)
                    {
                        iRow++;
                        iColumn = 0;
                        DataRow dr = dtFile.NewRow();
                        strLine = sr.ReadLine();

                        //read csv file line by line
                        string[] strRow = new string[iColumnCount];
                        string strChar;
                        int iCellNumber = 0;
                        bool blnQuote = false;//whether in the "" range
                        for (int i = 0; i < strLine.Length; i++)
                        {
                            strChar = strLine.Substring(i, 1);
                            if (strChar == ",")// "," is the seperation symbol of csv file,
                            {
                                if (!blnQuote)
                                {
                                    iCellNumber++;// out of the "" range, "," is the seperation symbol
                                    if (iCellNumber >= iColumnCount)// too many column in this line
                                    {
                                        break;
                                    }
                                }
                                else
                                {
                                    strRow[iCellNumber] += strChar;
                                }
                            }
                            else if (strChar == "\"")// "\"" is the transfer symbol of csv file,
                            {
                                blnQuote = !blnQuote;
                                if (blnQuote && i > 0 && strLine.Substring(i - 1, 1) == "\"")//in the "" range and there is an transfer symbol before
                                {
                                    strRow[iCellNumber] += strChar;
                                }
                            }
                            else
                            {
                                strRow[iCellNumber] += strChar;
                            }
                        }
                        if (iCellNumber + 1 == iColumnCount)
                        {
                            foreach (string strCell in strRow)
                            {
                                iColumn++;
                                if (strCell != null && strCell.Trim() != string.Empty)
                                {
                                    dr[strRowTitle[iColumn - 1]] = strCell.Trim();
                                }
                                else//file error:blank cell
                                {
                                    dr[strRowTitle[iColumn - 1]] = String.Empty;
                                    //errMessage += "The column \"" + strRowTitle[iColumn - 1] + "\" is blank in row " + iRow.ToString() + ".\r\n";
                                }
                            }
                        }
                        else// file error:the column count of current row do not equal to title's
                        {
                            errMessage += "There are more or less cells than title row in the row " + iRow.ToString() + ".\r\n";
                        }
                        dtFile.Rows.Add(dr);
                    }
                }
            }
            else //file error:the count of columns in the file don't equal it should be
            {
                errMessage += "There are an incorrect number of columns in the header row compared to the template file.\r\n";
            }
            sr.Close();
            sr.Dispose();

            errMessage = errMessage.Replace("\r\n", "<br>");
            return errMessage == String.Empty ? true : false;
        }


        /// <summary>
        /// Get dataset from csv file.
        /// </summary>
        /// <param name="filepath"></param>
        /// <param name="filename"></param>
        /// <returns>Data Set</returns>
        private DataSet GetDatasetFromCsv(string filepath, string filename)
        {
            string strconn = @"driver={microsoft text driver (*.txt; *.csv)};dbq=";
            strconn += filepath;                                                        //filepath, for example: c:\
            strconn += ";extensions=asc,csv,tab,txt;";
            OdbcConnection objconn = new OdbcConnection(strconn);
            DataSet dscsv = new DataSet();
            try
            {
                string strsql = "select * from " + filename;                     //filename, for example: 1.csv
                OdbcDataAdapter odbccsvdataadapter = new OdbcDataAdapter(strsql, objconn);

                odbccsvdataadapter.Fill(dscsv);
                return dscsv;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// Export to Csv File from dataset
        /// </summary>
        /// <param name="src"></param>
        /// <param name="folderName">folderName</param>
        /// <param name="strFileName">strFileName</param>
        /// <returns></returns>
        public bool ExportToCsv(DataSet src, string folderName, string strFileName)
        {
            string csv = String.Empty;

            StreamWriter writer = null;

            string fileName = Server.MapPath("/") + folderName + "\\" + strFileName;

            try
            {
                if (src == null || src.Tables.Count == 0) throw new Exception("dataset is null or has not table in dataset");


                for (int i = 0; i < src.Tables.Count; i++)
                {

                    if (i > 0)

                        fileName = fileName.Substring(0, fileName.IndexOf('.')) + i + fileName.Substring(fileName.IndexOf("."));



                    writer = new StreamWriter(fileName);

                    DataTable dt = src.Tables[i];

                    StringBuilder sb = new StringBuilder();

                    for (int j = 0; j < dt.Columns.Count; j++)
                    {

                        string colName = dt.Columns[j].ColumnName;

                        if (colName.IndexOf(',') > -1)

                            colName = colName.Insert(0, "\"").Insert(colName.Length + 1, "\"");

                        sb.Append(colName);

                        if (!colName.Equals(""))

                            if (j != dt.Columns.Count - 1)

                                sb.Append(",");

                    }

                    writer.WriteLine(sb.ToString());

                    sb = new StringBuilder();

                    string temp = "";

                    for (int j = 0; j < dt.Rows.Count; j++)
                    {

                        DataRow dr = dt.Rows[j];

                        for (int k = 0; k < dt.Columns.Count; k++)
                        {

                            object o = dr[k];

                            if (o != null)

                                temp = o.ToString();

                            if (temp.IndexOf(',') > -1)

                                temp = temp.Insert(0, "\"").Insert(temp.Length + 1, "\"");

                            sb.Append(temp);

                            if (k != dt.Columns.Count - 1)

                                sb.Append(",");

                        }

                        writer.WriteLine(sb.ToString());

                        sb = new StringBuilder();
                        csv = sb.ToString();
                    }

                    writer.Close();

                }

                string strFilePath = Server.MapPath("/") + folderName;
                if (!Directory.Exists(strFilePath))
                {
                    Directory.CreateDirectory(strFilePath);
                }

                strFullFileName = Server.MapPath("/") + folderName + "\\" + fileName;
                //FullFileName = Server.MapPath(FileName);
                //FileName
                FileInfo DownloadFile = new FileInfo(strFullFileName);
                if (DownloadFile.Exists)
                {
                    Response.Clear();
                    Response.ClearHeaders();
                    Response.Buffer = false;
                    Response.ContentType = "application/octet-stream";
                    //Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(DownloadFile.FullName, System.Text.Encoding.ASCII));
                    Response.AppendHeader("Content-Disposition", "attachment;filename=" + HttpUtility.UrlEncode(fileName, System.Text.Encoding.ASCII));
                    Response.AppendHeader("Content-Length", DownloadFile.Length.ToString());
                    Response.WriteFile(DownloadFile.FullName);
                    Response.Flush();
                    //Response.End();
                }
                else
                {
                    //not exist
                    throw new Exception("Export csv file does not exist!");
                }


            }

            catch (Exception ex)
            {

                throw new Exception("Save csv error", ex);

            }

            finally
            {

                if (writer != null) writer.Close();

            }

            return true;

        }

        /// <summary>
        /// List to DataTable
        /// </summary>
        /// <param name="entitys">entitys list</param>
        /// <returns></returns>
        public DataTable ListToDataTable(List<T> entitys)
        {

            //
            if (entitys == null || entitys.Count < 1)
            {
                throw new Exception("list is null");
            }

            //get first Propertie
            Type entityType = entitys[0].GetType();
            PropertyInfo[] entityProperties = entityType.GetProperties();

            //DataTable structure
            //
            DataTable dt = new DataTable();
            for (int i = 0; i < entityProperties.Length; i++)
            {
                //dt.Columns.Add(entityProperties[i].Name, entityProperties[i].PropertyType);
                dt.Columns.Add(entityProperties[i].Name);
            }

            //add entity to DataTable
            foreach (object entity in entitys)
            {
                //check type
                if (entity.GetType() != entityType)
                {
                    throw new Exception("type not same");
                }
                object[] entityValues = new object[entityProperties.Length];
                for (int i = 0; i < entityProperties.Length; i++)
                {
                    entityValues[i] = entityProperties[i].GetValue(entity, null);

                }
                dt.Rows.Add(entityValues);
            }
            return dt;
        }