Create new tool for CSV

最新推荐文章于 2025-08-13 14:59:35 发布

weixin_30920513

最新推荐文章于 2025-08-13 14:59:35 发布

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CC 4.0 BY-SA版权

文章标签：操作系统数据结构与算法

原文链接：http://www.cnblogs.com/vincentDr/p/3600664.html

本文详细介绍了CSVFileStream和CsvFileWriter类的功能，包括如何使用这些类进行CSV文件的读取、写入和解析。重点阐述了如何通过CSVFileStream类获取CSV文件的每一行数据，并通过CsvFileWriter类实现CSV文件的高效写入与格式化。

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CsvFileStream.cs

public class CsvFileStream
    {
        TextReader stream;
        bool EOS = false;
        bool EOL = false;

        public CsvFileStream(TextReader s)
        {
            stream = s;
        }

        public string[] GetNextRow()
        {
            ArrayList row = new ArrayList();
            while (true)
            {
                string item = GetNextItem();
                if (item == null)
                    return row.Count == 0 ? null : (string[])row.ToArray(typeof(string));
                row.Add(item);
            }
        }

        string GetNextItem()
        {
            if (EOL)
            {
                // previous item was last in line, start new line
                EOL = false;
                return null;
            }

            bool quoted = false;
            bool predata = true;
            bool postdata = false;
            StringBuilder sb = new StringBuilder();

            while (true)
            {
                char c = GetNextChar(true);
                if (EOS)
                    return sb.Length > 0 ? sb.ToString() : null;

                if ((postdata || !quoted) && c == ',')
                    // end of item, return
                    return sb.ToString();

                if ((predata || postdata || !quoted) && (c == '\x0A' || c == '\x0D'))
                {
                    // we are at the end of the line, eat newline characters and exit
                    EOL = true;
                    if (c == '\x0D' && GetNextChar(false) == '\x0A')
                        // new line sequence is 0D0A
                        GetNextChar(true);
                    return sb.ToString();
                }

                if (predata && c == ' ')
                    // whitespace preceeding data, discard
                    continue;

                if (predata && c == '"')
                {
                    // quoted data is starting
                    quoted = true;
                    predata = false;
                    continue;
                }

                if (predata)
                {
                    // data is starting without quotes
                    predata = false;
                    sb.Append(c);
                    continue;
                }

                if (c == '"' && quoted)
                {
                    if (GetNextChar(false) == '"')
                        // double quotes within quoted string means add a quote       
                        sb.Append(GetNextChar(true));
                    else
                        // end-quote reached
                        postdata = true;
                    continue;
                }

                // all cases covered, character must be data
                sb.Append(c);
            }
        }

        char[] buffer = new char[4096];
        int pos = 0;
        int length = 0;

        char GetNextChar(bool eat)
        {
            if (pos >= length)
            {
                length = stream.ReadBlock(buffer, 0, buffer.Length);
                if (length == 0)
                {
                    EOS = true;
                    return '\0';
                }
                pos = 0;
            }
            if (eat)
                return buffer[pos++];
            else
                return buffer[pos];
        }
    }

CsvFileWriter.cs

public class CsvFileWriter
    {
        private ArrayList rowAL;        //行链表,CSV文件的每一行就是一个链
        private string fileName;       //文件名
        private Encoding encoding;       //编码

        public CsvFileWriter()
        {
            this.rowAL = new ArrayList();
            this.fileName = "";
            this.encoding = Encoding.Default;
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="fileName">文件名,包括文件路径</param>
        public CsvFileWriter(string fileName)
        {
            this.rowAL = new ArrayList();
            this.fileName = fileName;
            this.encoding = Encoding.Default;
        }

        /// <summary>
        /// 
        /// </summary>
        /// <param name="fileName">文件名,包括文件路径</param>
        /// <param name="encoding">文件编码</param>
        public CsvFileWriter(string fileName, Encoding encoding)
        {
            this.rowAL = new ArrayList();
            this.fileName = fileName;
            this.encoding = encoding;
        }

        /// <summary>
        /// row:行,row = 1代表第一行
        /// col:列,col = 1代表第一列
        /// </summary>
        public string this[int row, int col]
        {
            set
            {
                //对行进行判断
                if (row <= 0)
                {
                    throw new Exception("行数不能小于0");
                }
                else if (row > this.rowAL.Count) //如果当前列链的行数不够，要补齐
                {
                    for (int i = this.rowAL.Count + 1; i <= row; i++)
                    {
                        this.rowAL.Add(new ArrayList());
                    }
                }
                else
                {
                }
                //对列进行判断
                if (col <= 0)
                {
                    throw new Exception("列数不能小于0");
                }
                else
                {
                    ArrayList colTempAL = (ArrayList)this.rowAL[row - 1];

                    //扩大长度
                    if (col > colTempAL.Count)
                    {
                        for (int i = colTempAL.Count; i <= col; i++)
                        {
                            colTempAL.Add("");
                        }
                    }
                    this.rowAL[row - 1] = colTempAL;
                }
                //赋值
                ArrayList colAL = (ArrayList)this.rowAL[row - 1];

                colAL[col - 1] = value;
                this.rowAL[row - 1] = colAL;
            }
        }

        /// <summary>
        /// 文件名,包括文件路径
        /// </summary>
        public string FileName
        {
            set
            {
                this.fileName = value;
            }
        }

        /// <summary>
        /// 文件编码
        /// </summary>

        public Encoding FileEncoding
        {
            set
            {
                this.encoding = value;
            }
        }

        /// <summary>
        /// 获取当前最大行
        /// </summary>
        public int CurMaxRow
        {
            get
            {
                return this.rowAL.Count;
            }
        }

        /// <summary>
        /// 获取最大列
        /// </summary>
        public int CurMaxCol
        {
            get
            {
                int maxCol;

                maxCol = 0;
                for (int i = 0; i < this.rowAL.Count; i++)
                {
                    ArrayList colAL = (ArrayList)this.rowAL[i];

                    maxCol = (maxCol > colAL.Count) ? maxCol : colAL.Count;
                }

                return maxCol;
            }
        }

        /// <summary>
        /// 添加表数据到CSV文件中
        /// </summary>
        /// <param name="dataDT">表数据</param>
        /// <param name="beginCol">从第几列开始,beginCol = 1代表第一列</param>
        public void AddData(DataTable dataDT, int beginCol)
        {
            if (dataDT == null)
            {
                throw new Exception("需要添加的表数据为空");
            }
            int curMaxRow;

            curMaxRow = this.rowAL.Count;
            for (int i = 0; i < dataDT.Rows.Count; i++)
            {
                for (int j = 0; j < dataDT.Columns.Count; j++)
                {
                    this[curMaxRow + i + 1, beginCol + j] = dataDT.Rows[i][j].ToString();
                }
            }
        }

        /// <summary>
        /// 保存数据,如果当前硬盘中已经存在文件名一样的文件，将会覆盖
        /// </summary>
        public void Save()
        {
            //对数据的有效性进行判断
            if (this.fileName == null)
            {
                throw new Exception("缺少文件名");
            }
            else if (File.Exists(this.fileName))
            {
                File.Delete(this.fileName);
            }
            if (this.encoding == null)
            {
                this.encoding = Encoding.Default;
            }
            System.IO.StreamWriter sw = new StreamWriter(this.fileName, false, this.encoding);

            for (int i = 0; i < this.rowAL.Count; i++)
            {
                sw.WriteLine(ConvertToSaveLine((ArrayList)this.rowAL[i]));
            }

            sw.Close();
        }

        /// <summary>
        /// 保存数据,如果当前硬盘中已经存在文件名一样的文件，将会覆盖
        /// </summary>
        /// <param name="fileName">文件名,包括文件路径</param>
        public void Save(string fileName)
        {
            this.fileName = fileName;
            Save();
        }

        /// <summary>
        /// 保存数据,如果当前硬盘中已经存在文件名一样的文件，将会覆盖
        /// </summary>
        /// <param name="fileName">文件名,包括文件路径</param>
        /// <param name="encoding">文件编码</param>
        public void Save(string fileName, Encoding encoding)
        {
            this.fileName = fileName;
            this.encoding = encoding;
            Save();
        }

        /// <summary>
        /// 转换成保存行
        /// </summary>
        /// <param name="colAL">一行</param>
        /// <returns></returns>
        private string ConvertToSaveLine(ArrayList colAL)
        {
            string saveLine;

            saveLine = "";
            for (int i = 0; i < colAL.Count; i++)
            {
                saveLine += ConvertToSaveCell(colAL[i].ToString());
                //格子间以逗号分割
                if (i < colAL.Count - 1)
                {
                    saveLine += ",";
                }
            }

            return saveLine;
        }

        /// <summary>
        /// 字符串转换成CSV中的格子
        /// 双引号转换成两个双引号，然后首尾各加一个双引号
        /// 这样就不需要考虑逗号及换行的问题
        /// </summary>
        /// <param name="cell">格子内容</param>
        /// <returns></returns>
        private string ConvertToSaveCell(string cell)
        {
            cell = cell.Replace("\"","\"\"");

            return "\"" + cell + "\"";
            //return "";
        }
    }

CsvFileReader.cs

public class CsvFileReader
    {
        public static DataTable Parse(string data, bool headers)
        {
            return Parse(new StringReader(data), headers);
        }

        public static DataTable Parse(string data)
        {
            return Parse(new StringReader(data));
        }

        public static DataTable Parse(TextReader stream)
        {
            return Parse(stream, false);
        }

        public static DataTable Parse(TextReader stream, bool headers)
        {
            DataTable table = new DataTable();

            CsvFileStream csv = new CsvFileStream(stream);
            string[] row = csv.GetNextRow();
            if (row == null) return null;

            if (headers)
            {
                foreach (string header in row)
                {
                    if (header != null && header.Length > 0 && !table.Columns.Contains(header))
                        table.Columns.Add(header, typeof(string));
                    else
                        table.Columns.Add(GetNextColumnHeader(table), typeof(string));
                }
                row = csv.GetNextRow();
            }

            while (row != null)
            {
                while (row.Length > table.Columns.Count)
                    table.Columns.Add(GetNextColumnHeader(table), typeof(string));
                table.Rows.Add(row);
                row = csv.GetNextRow();
            }
            return table;
        }

        static string GetNextColumnHeader(DataTable table)
        {
            int c = 1;
            while (true)
            {
                string h = "Column" + c++;
                if (!table.Columns.Contains(h))
                    return h;
            }
        }
    }

eg.

TextReader reader = new StreamReader(@"D:\test.csv");
DataTable dt = CsvFileReader.Parse(reader, false);

转载于:https://www.cnblogs.com/vincentDr/p/3600664.html