C#工具:CSV文件转换帮助类

csv是逗号分隔值格式的文件，其文件以纯文本形式存储表格数据（数字和文本）。csv文件由任意数目的记录组成，记录间以某种换行符分隔；每条记录由字段组成，字段间的分隔符是其它字符或字符串，最常见的是逗号或制表符。在c#中有时候需要读取和写入csv文件，特此封装了一个工具类csvhelper。特此说一句，c#将数据导出到csv文件的速度比较快，有时候导出excel文件很慢的时候可以选择先导出.csv文件，而后再本地用excel软件打开。

csvhelper类主要是利用c#操作csv文件，主要包含2个方法。

dt2csv(参数略)：将数据导入到csv文件中

csv2dt(参数略)：将csv读入datatable

具体的工具类实现如下：

 

using system;
using system.collections.generic;
using system.text;
using system.io;
using system.data;
using system.data.oledb;


namespace core.io
{
    /// <summary>
    /// csv文件转换类
    /// </summary>
    public static class csvhelper
    {
        /// <summary>
        /// 导出报表为csv
        /// </summary>
        /// <param name="dt">datatable</param>
        /// <param name="strfilepath">物理路径</param>
        /// <param name="tableheader">表头</param>
        /// <param name="columname">字段标题,逗号分隔</param>
        public static bool dt2csv(datatable dt, string strfilepath, string tableheader, string columname)
        {
            try
            {
                string strbufferline = "";
                streamwriter strmwriterobj = new streamwriter(strfilepath, false, system.text.encoding.utf8);
                strmwriterobj.writeline(tableheader);
                strmwriterobj.writeline(columname);
                for (int i = 0; i < dt.rows.count; i++)
                {
                    strbufferline = "";
                    for (int j = 0; j < dt.columns.count; j++)
                    {
                        if (j > 0)
                            strbufferline += ",";
                        strbufferline += dt.rows[i][j].tostring();
                    }
                    strmwriterobj.writeline(strbufferline);
                }
                strmwriterobj.close();
                return true;
            }
            catch
            {
                return false;
            }
        }

        /// <summary>
        /// 将csv读入datatable
        /// </summary>
        /// <param name="filepath">csv文件路径</param>
        /// <param name="n">表示第n行是字段title,第n+1行是记录开始</param>
        public static datatable csv2dt(string filepath, int n, datatable dt)
        {
            streamreader reader = new streamreader(filepath, system.text.encoding.utf8, false);
            int i = 0, m = 0;
            reader.peek();
            while (reader.peek() > 0)
            {
                m = m + 1;
                string str = reader.readline();
                if (m >= n + 1)
                {
                    string[] split = str.split(',');

                    system.data.datarow dr = dt.newrow();
                    for (i = 0; i < split.length; i++)
                    {
                        dr[i] = split[i];
                    }
                    dt.rows.add(dr);
                }
            }
            return dt;
        }

        /// <summary>
        /// csv转换成datatable（oledb数据库访问方式）
        /// </summary>
        /// <param name="csvpath">csv文件路径</param>
        /// <returns></returns>
        public static datatable csvtodatatablebyoledb(string csvpath)
        {
            datatable csvdt = new datatable("csv");
            if (!file.exists(csvpath))
            {
                throw new filenotfoundexception("csv文件路径不存在!");
            }

            fileinfo fileinfo = new fileinfo(csvpath);
            using (oledbconnection conn = new oledbconnection(@"provider=microsoft.jet.oledb.4.0;data source=" + fileinfo.directoryname + ";extended properties='text;'"))
            {
                oledbdataadapter adapter = new oledbdataadapter("select * from [" + fileinfo.name + "]", conn);
                adapter.fill(csvdt);
            }
            return csvdt;
        }

        /// <summary>
        /// csv转换成datatable（文件流方式）
        /// </summary>
        /// <param name="csvpath">csv文件路径</param>
        /// <returns></returns>
        public static datatable csvtodatatablebystreamreader(string csvpath)
        {
            datatable csvdt = new datatable("csv");

            int intcolcount = 0;
            bool blnflag = true;
            datacolumn column;
            datarow row;
            string strline = null;
            string[] aryline;

            using (streamreader reader = new streamreader(csvpath, fileencoding.getencoding(csvpath)))
            {
                while (!string.isnullorempty((strline = reader.readline())))
                {
                    aryline = strline.split(new char[] { ',' });

                    if (blnflag)
                    {
                        blnflag = false;
                        intcolcount = aryline.length;
                        for (int i = 0; i < aryline.length; i++)
                        {
                            column = new datacolumn(aryline[i]);
                            csvdt.columns.add(column);
                        }
                        continue;
                    }

                    row = csvdt.newrow();
                    for (int i = 0; i < intcolcount; i++)
                    {
                        row[i] = aryline[i];
                    }
                    csvdt.rows.add(row);
                }
            }

            return csvdt;
        }

        /// <summary>
        /// datatable 生成 csv
        /// </summary>
        /// <param name="dt">datatable</param>
        /// <param name="csvpath">csv文件路径</param>
        public static void datatabletocsv(datatable dt, string csvpath)
        {
            if (null == dt)
                return;

            stringbuilder csvtext = new stringbuilder();
            stringbuilder csvrowtext = new stringbuilder();
            foreach (datacolumn dc in dt.columns)
            {
                csvrowtext.append(",");
                csvrowtext.append(dc.columnname);
            }
            csvtext.appendline(csvrowtext.tostring().substring(1));

            foreach (datarow dr in dt.rows)
            {
                csvrowtext = new stringbuilder();
                foreach (datacolumn dc in dt.columns)
                {
                    csvrowtext.append(",");
                    csvrowtext.append(dr[dc.columnname].tostring().replace(',', ' '));
                }
                csvtext.appendline(csvrowtext.tostring().substring(1));
            }

            file.writealltext(csvpath, csvtext.tostring(), encoding.default);
        }
    
    }
}

csvhelper