.NET读写CSV文件

1、引入以下命名空间

using System;
using System.Data;
using System.IO;

2、将DataTable写入CSV文件

/// <summary>
/// 写入CSV文件
/// </summary>
/// <param name="dt">DataTable</param>
/// <param name="fullFileName">文件全名</param>
/// <returns>是否写入成功</returns>
public static bool SaveCSV(DataTable dt, string fullFileName)
{
    bool r = false;
    FileStream fs = new FileStream(fullFileName, System.IO.FileMode.Create, System.IO.FileAccess.Write);
    StreamWriter sw = new StreamWriter(fs, System.Text.Encoding.Default);
    string data = string.Empty;

    //写出列名称
    for (int i = 0; i < dt.Columns.Count; i++)
    {
        data += dt.Columns[i].ColumnName.ToString();
        if (i < dt.Columns.Count - 1)
        {
            data += ",";
        }
    }
    sw.WriteLine(data);

    //写入各行数据
    for (int i = 0; i < dt.Rows.Count; i++)
    {
        data = string.Empty;
        for (int j = 0; j < dt.Columns.Count; j++)
        {
            data += dt.Rows[i][j].ToString();
            if (j < dt.Columns.Count - 1)
            {
                data += ",";
            }
        }
        sw.WriteLine(data);
    }

    sw.Close();
    fs.Close();

    r = true;
    return r;
}

3、打开CSV文件，返回DataTable

/// <summary>
/// 打开CSV 文件
/// </summary>
/// <param name="fullFileName">文件全名</param>
/// <param name="firstRow">开始行</param>
/// <param name="firstColumn">开始列</param>
/// <param name="getRows">获取多少行</param>
/// <param name="getColumns">获取多少列</param>
/// <param name="haveTitleRow">是有标题行</param>
/// <returns>DataTable</returns>
public static DataTable OpenCSV(string fullFileName, int firstRow = 0, int firstColumn = 0, int getRows = 0, int getColumns = 0, bool haveTitleRow = false)
{
    try
    {
        DataTable dt = new DataTable();
        FileStream fs = new FileStream(fullFileName, System.IO.FileMode.Open, System.IO.FileAccess.Read);
        StreamReader sr = new StreamReader(fs, System.Text.Encoding.Default);
        //记录每次读取的一行记录
        string strLine = string.Empty;
        //记录每行记录中的各字段内容
        string[] aryLine;
        //标示列数
        int columnCount = 0;
        //是否已建立了表的字段
        bool bCreateTableColumns = false;
        //第几行
        int iRow = 1;

        //去除无用行
        if (firstRow > 0)
        {
            for (int i = 1; i < firstRow; i++)
            {
                sr.ReadLine();
            }
        }

        // { ",", ".", "!", "?", ";", ":", " " };
        string[] separators = { "," };
        //逐行读取CSV中的数据
        while ((strLine = sr.ReadLine()) != null)
        {
            strLine = strLine.Trim();

            while (strLine.Contains(",,"))
            {
                strLine = strLine.Replace(",,", ",0,");
            }
            aryLine = strLine.Split(separators, System.StringSplitOptions.RemoveEmptyEntries);

            if (bCreateTableColumns == false)
            {
                bCreateTableColumns = true;
                columnCount = aryLine.Length;
                //创建列
                for (int i = firstColumn; i < (getColumns == 0 ? columnCount : firstColumn + getColumns); i++)
                {
                    DataColumn dc
                        = new DataColumn(haveTitleRow == true ? aryLine[i] : "COL" + i.ToString());
                    dt.Columns.Add(dc);
                }

                bCreateTableColumns = true;

                if (haveTitleRow == true)
                {
                    continue;
                }
            }


            DataRow dr = dt.NewRow();
            //for (int j = firstColumn; j < (getColumns == 0 ? columnCount : firstColumn + getColumns); j++)
            for (int j = firstColumn; j < aryLine.Length; j++)
            {
                if (j < dt.Columns.Count)
                {
                    dr[j - firstColumn] = aryLine[j];
                }

            }
            dt.Rows.Add(dr);

            iRow = iRow + 1;
            if (getRows > 0)
            {
                if (iRow > getRows)
                {
                    break;
                }
            }

        }

        sr.Close();
        fs.Close();
        return dt;
    }
    catch (Exception ex)
    {
        throw ex;
    }
}