CSV和Excel大致相同  复制下来 数据传到方法里面就可以了

/// <summary>
/// DataTable数据写入CSV文件
/// </summary>
/// <param name="dt"></param>
/// <param name="fullPath"></param>
public void SaveCSV(DataTable dt, string fullPath)//table数据写入csv
{
System.IO.FileInfo fi = new System.IO.FileInfo(fullPath);
if (!fi.Directory.Exists)
{
fi.Directory.Create();
}
System.IO.FileStream fs = new System.IO.FileStream(fullPath, System.IO.FileMode.Create,
System.IO.FileAccess.Write);
System.IO.StreamWriter sw = new System.IO.StreamWriter(fs, System.Text.Encoding.UTF8);
string data = "";

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

for (int i = 0; i < dt.Rows.Count; i++) //写入各行数据
{
data = "";
for (int j = 0; j < dt.Columns.Count; j++)
{
string str = dt.Rows[i][j].ToString();
str = str.Replace("\"", "\"\"");//替换英文冒号 英文冒号需要换成两个冒号
if (str.Contains(',') || str.Contains('"')
|| str.Contains('\r') || str.Contains('\n')) //含逗号 冒号 换行符的需要放到引号中
{
str = string.Format("\"{0}\"", str);
}

data += str;
if (j < dt.Columns.Count - 1)
{
data += ",";
}
}
sw.WriteLine(data);
}
sw.Close();
fs.Close();
}

/// <summary>
/// 读取CSV文件到DataTable
/// </summary>
/// <param name="filePath"></param>
/// <returns></returns>
public DataTable OpenCSV(string filePath)//从csv读取数据返回table
{
System.Text.Encoding encoding = GetType(filePath); //Encoding.ASCII;//
DataTable dt = new DataTable();
System.IO.FileStream fs = new System.IO.FileStream(filePath, System.IO.FileMode.Open,
System.IO.FileAccess.Read);

System.IO.StreamReader sr = new System.IO.StreamReader(fs, encoding);

//记录每次读取的一行记录
string strLine = "";
//记录每行记录中的各字段内容
string[] aryLine = null;
string[] tableHead = null;
//标示列数
int columnCount = 0;
//标示是否是读取的第一行
bool IsFirst = true;
//逐行读取CSV中的数据
while ((strLine = sr.ReadLine()) != null)
{
if (IsFirst == true)
{
tableHead = strLine.Split(',');
IsFirst = false;
columnCount = tableHead.Length;
//创建列
for (int i = 0; i < columnCount; i++)
{
DataColumn dc = new DataColumn(tableHead[i]);
dt.Columns.Add(dc);
}
}
else
{
aryLine = strLine.Split(',');
DataRow dr = dt.NewRow();
for (int j = 0; j < columnCount; j++)
{
dr[j] = aryLine[j];
}
dt.Rows.Add(dr);
}
}
if (aryLine != null && aryLine.Length > 0)
{
dt.DefaultView.Sort = tableHead[0] + " " + "asc";
}

sr.Close();
fs.Close();
return dt;
}
/// 给定文件的路径，读取文件的二进制数据，判断文件的编码类型
/// <param name="FILE_NAME">文件路径</param>
/// <returns>文件的编码类型</returns>

public static System.Text.Encoding GetType(string FILE_NAME)
{
System.IO.FileStream fs = new System.IO.FileStream(FILE_NAME, System.IO.FileMode.Open,
System.IO.FileAccess.Read);
System.Text.Encoding r = GetType(fs);
fs.Close();
return r;
}

/// 通过给定的文件流，判断文件的编码类型
/// <param name="fs">文件流</param>
/// <returns>文件的编码类型</returns>
public static System.Text.Encoding GetType(System.IO.FileStream fs)
{
byte[] Unicode = new byte[] { 0xFF, 0xFE, 0x41 };
byte[] UnicodeBIG = new byte[] { 0xFE, 0xFF, 0x00 };
byte[] UTF8 = new byte[] { 0xEF, 0xBB, 0xBF }; //带BOM
System.Text.Encoding reVal = System.Text.Encoding.Default;

System.IO.BinaryReader r = new System.IO.BinaryReader(fs, System.Text.Encoding.Default);
int i;
int.TryParse(fs.Length.ToString(), out i);
byte[] ss = r.ReadBytes(i);
if (IsUTF8Bytes(ss) || (ss[0] == 0xEF && ss[1] == 0xBB && ss[2] == 0xBF))
{
reVal = System.Text.Encoding.UTF8;
}
else if (ss[0] == 0xFE && ss[1] == 0xFF && ss[2] == 0x00)
{
reVal = System.Text.Encoding.BigEndianUnicode;
}
else if (ss[0] == 0xFF && ss[1] == 0xFE && ss[2] == 0x41)
{
reVal = System.Text.Encoding.Unicode;
}
r.Close();
return reVal;
}

/// 判断是否是不带 BOM 的 UTF8 格式
/// <param name="data"></param>
/// <returns></returns>
private static bool IsUTF8Bytes(byte[] data)
{
int charByteCounter = 1; //计算当前正分析的字符应还有的字节数
byte curByte; //当前分析的字节.
for (int i = 0; i < data.Length; i++)
{
curByte = data[i];
if (charByteCounter == 1)
{
if (curByte >= 0x80)
{
//判断当前
while (((curByte <<= 1) & 0x80) != 0)
{
charByteCounter++;
}
//标记位首位若为非0 则至少以2个1开始 如:110XXXXX...........1111110X　
if (charByteCounter == 1 || charByteCounter > 6)
{
return false;
}
}
}
else
{
//若是UTF-8 此时第一位必须为1
if ((curByte & 0xC0) != 0x80)
{
return false;
}
charByteCounter--;
}
}
if (charByteCounter > 1)
{
throw new Exception("非预期的byte格式");
}
return true;
}
/// <summary>
/// 修改文件名称
/// 我们需要保存历史数据 或者实时的知道那个文件被修改 可以通过改变文件的名称 如加上当天的日期等等。
/// </summary>
/// <param name="OldPath"></param>
/// <param name="NewPath"></param>
/// <returns></returns>
public static bool ChangeFileName(string OldPath, string NewPath)
{
bool re = false;
try
{
if (File.Exists(OldPath))
{
File.Move(OldPath, NewPath);
re = true;
}
}
catch
{
re = false;
}
return re;
}

/// <summary>
/// CSV文件的数据写入
/// 直接在网页表单提交数据保存在csv文件中 直接写入文件
/// </summary>
/// <param name="fullPath"></param>
/// <param name="Data"></param>
/// <returns></returns>
public static bool SaveCSV(string fullPath, string Data)
{
bool re = true;
try
{
FileStream FileStream = new FileStream(fullPath, FileMode.Append);
StreamWriter sw = new StreamWriter(FileStream, System.Text.Encoding.UTF8);
sw.WriteLine(Data);
//清空缓冲区
sw.Flush();
//关闭流
sw.Close();
FileStream.Close();
}
catch
{
re = false;
}
return re;
}