C# CSV文件读写

1public class CSVFileHelper
2{
3    /// <summary>
4    /// 将DataTable中数据写入到CSV文件中
5    /// </summary>
6    /// <param name="dt">提供保存数据的DataTable</param>
7    /// <param name="fileName">CSV的文件路径</param>
8    public static void SaveCSV(DataTable dt, string fullPath)
9    {
10        FileInfo fi = new FileInfo(fullPath);
11        if (!fi.Directory.Exists)
12        {
13            fi.Directory.Create();
14        }
15        FileStream fs = new FileStream(fullPath, System.IO.FileMode.Create, System.IO.FileAccess.Write);
16        //StreamWriter sw = new StreamWriter(fs, System.Text.Encoding.Default);
17        StreamWriter sw = new StreamWriter(fs, System.Text.Encoding.UTF8);
18        string data = "";
19        //写出列名称
20        for (int i = 0; i < dt.Columns.Count; i++)
21        {
22            data += dt.Columns[i].ColumnName.ToString();
23            if (i < dt.Columns.Count - 1)
24            {
25                data += ",";
26            }
27        }
28        sw.WriteLine(data);
29        //写出各行数据
30        for (int i = 0; i < dt.Rows.Count; i++)
31        {
32            data = "";
33            for (int j = 0; j < dt.Columns.Count; j++)
34            {
35                string str = dt.Rows[i][j].ToString();
36                str = str.Replace("\"", "\"\"");//替换英文冒号 英文冒号需要换成两个冒号
37                if (str.Contains(',') || str.Contains('"') 
38                    || str.Contains('\r') || str.Contains('\n')) //含逗号 冒号 换行符的需要放到引号中
39                {
40                    str = string.Format("\"{0}\"", str);
41                }
42
43                data += str;
44                if (j < dt.Columns.Count - 1)
45                {
46                    data += ",";
47                }
48            }
49            sw.WriteLine(data);
50        }
51        sw.Close();
52        fs.Close();
53        DialogResult result = MessageBox.Show("CSV文件保存成功！");
54        if (result == DialogResult.OK)
55        {
56            System.Diagnostics.Process.Start("explorer.exe", Common.PATH_LANG);
57        }
58    }
59
60    /// <summary>
61    /// 将CSV文件的数据读取到DataTable中
62    /// </summary>
63    /// <param name="fileName">CSV文件路径</param>
64    /// <returns>返回读取了CSV数据的DataTable</returns>
65    public static DataTable OpenCSV(string filePath)
66    {
67        Encoding encoding = Common.GetType(filePath); //Encoding.ASCII;//
68        DataTable dt = new DataTable();
69        FileStream fs = new FileStream(filePath, System.IO.FileMode.Open, System.IO.FileAccess.Read);
70        
71        //StreamReader sr = new StreamReader(fs, Encoding.UTF8);
72        StreamReader sr = new StreamReader(fs, encoding);
73        //string fileContent = sr.ReadToEnd();
74        //encoding = sr.CurrentEncoding;
75        //记录每次读取的一行记录
76        string strLine = "";
77        //记录每行记录中的各字段内容
78        string[] aryLine = null;
79        string[] tableHead = null;
80        //标示列数
81        int columnCount = 0;
82        //标示是否是读取的第一行
83        bool IsFirst = true;
84        //逐行读取CSV中的数据
85        while ((strLine = sr.ReadLine()) != null)
86        {
87            //strLine = Common.ConvertStringUTF8(strLine, encoding);
88            //strLine = Common.ConvertStringUTF8(strLine);
89
90            if (IsFirst == true)
91            {
92                tableHead = strLine.Split(',');
93                IsFirst = false;
94                columnCount = tableHead.Length;
95                //创建列
96                for (int i = 0; i < columnCount; i++)
97                {
98                    DataColumn dc = new DataColumn(tableHead[i]);
99                    dt.Columns.Add(dc);
100                }
101            }
102            else
103            {
104                aryLine = strLine.Split(',');
105                DataRow dr = dt.NewRow();
106                for (int j = 0; j < columnCount; j++)
107                {
108                    dr[j] = aryLine[j];
109                }
110                dt.Rows.Add(dr);
111            }
112        }
113        if (aryLine != null && aryLine.Length > 0)
114        {
115            dt.DefaultView.Sort = tableHead[0] + " " + "asc";
116        }
117        
118        sr.Close();
119        fs.Close();
120        return dt;
121    }
122}
123
124/// 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
125/// <param name="FILE_NAME">文件路径</param>
126/// <returns>文件的编码类型</returns>
127 
128public static System.Text.Encoding GetType(string FILE_NAME)
129{
130    System.IO.FileStream fs = new System.IO.FileStream(FILE_NAME, System.IO.FileMode.Open,
131        System.IO.FileAccess.Read);
132    System.Text.Encoding r = GetType(fs);
133    fs.Close();
134    return r;
135}
136 
137/// 通过给定的文件流，判断文件的编码类型
138/// <param name="fs">文件流</param>
139/// <returns>文件的编码类型</returns>
140public static System.Text.Encoding GetType(System.IO.FileStream fs)
141{
142    byte[] Unicode = new byte[] { 0xFF, 0xFE, 0x41 };
143    byte[] UnicodeBIG = new byte[] { 0xFE, 0xFF, 0x00 };
144    byte[] UTF8 = new byte[] { 0xEF, 0xBB, 0xBF }; //带BOM
145    System.Text.Encoding reVal = System.Text.Encoding.Default;
146 
147    System.IO.BinaryReader r = new System.IO.BinaryReader(fs, System.Text.Encoding.Default);
148    int i;
149    int.TryParse(fs.Length.ToString(), out i);
150    byte[] ss = r.ReadBytes(i);
151    if (IsUTF8Bytes(ss) || (ss[0] == 0xEF && ss[1] == 0xBB && ss[2] == 0xBF))
152    {
153        reVal = System.Text.Encoding.UTF8;
154    }
155    else if (ss[0] == 0xFE && ss[1] == 0xFF && ss[2] == 0x00)
156    {
157        reVal = System.Text.Encoding.BigEndianUnicode;
158    }
159    else if (ss[0] == 0xFF && ss[1] == 0xFE && ss[2] == 0x41)
160    {
161        reVal = System.Text.Encoding.Unicode;
162    }
163    r.Close();
164    return reVal;
165}
166 
167/// 判断是否是不带 BOM 的 UTF8 格式
168/// <param name="data"></param>
169/// <returns></returns>
170private static bool IsUTF8Bytes(byte[] data)
171{
172    int charByteCounter = 1;　 //计算当前正分析的字符应还有的字节数
173    byte curByte; //当前分析的字节.
174    for (int i = 0; i < data.Length; i++)
175    {
176        curByte = data[i];
177        if (charByteCounter == 1)
178        {
179            if (curByte >= 0x80)
180            {
181                //判断当前
182                while (((curByte <<= 1) & 0x80) != 0)
183                {
184                    charByteCounter++;
185                }
186                //标记位首位若为非0 则至少以2个1开始 如:110XXXXX...........1111110X　
187                if (charByteCounter == 1 || charByteCounter > 6)
188                {
189                    return false;
190                }
191            }
192        }
193        else
194        {
195            //若是UTF-8 此时第一位必须为1
196            if ((curByte & 0xC0) != 0x80)
197            {
198                return false;
199            }
200            charByteCounter--;
201        }
202    }
203    if (charByteCounter > 1)
204    {
205        throw new Exception("非预期的byte格式");
206    }
207    return true;
208}