C# 讀取 CSV 文件

最近作一個C#項目要導入CSV文件中的數據到Oracle中，使用Aspose.Cells讀取中文字段標題卻亂碼，表的最後多出幾行null記錄，並且不是免費的，後來找到了NPOI，顧名思義，就是POI的.NET版本，POI是一套用Java寫成的庫，可以幫助開發者在沒有安裝微軟Office的狀況下讀寫Office 97-2003的文件，支持的文件格式包括xls, doc,
ppt等。並且是免費的，學了半天，得出一個結論，殺雞用牛刀。最後決定自已寫一個讀取及寫入CSV文件的代碼，效果很是好。現分享受應趣的朋友門。

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

namespace DBUtility
{
    public static class CsvHelper
    {
        /// <summary>
        /// 寫入CSV文件
        /// </summary>
        /// <param name="dt">DataTable</param>
        /// <param name="fileName">文件全名</param>
        /// <returns>是否寫入成功</returns>
        public static Boolean SaveCSV(DataTable dt, string fullFileName)
        {
            Boolean 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 = "";

            //寫出列名稱
            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);

            //寫出各行數據
            for (int i = 0; i < dt.Rows.Count; i++)
            {
                data = "";
                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;  
        }

        /// <summary>
        /// 打開CSV 文件
        /// </summary>
        /// <param name="fileName">文件全名</param>
        /// <returns>DataTable</returns>
        public static DataTable OpenCSV(string fullFileName)
        {
            return OpenCSV(fullFileName, 0, 0, 0, 0, true);
        }

        /// <summary>
        /// 打開CSV 文件
        /// </summary>
        /// <param name="fileName">文件全名</param>
        /// <param name="firstRow">開始行</param>
        /// <param name="firstColumn">開始列</param>
        /// <param name="getRows">獲取多少行</param>
        /// <param name="getColumns">獲取多少列</param>
        /// <param name="haveTitleRow">是有標題行</param>
        /// <returns>DataTable</returns>
        public static DataTable OpenCSV(string fullFileName, Int16 firstRow = 0, Int16 firstColumn = 0, Int16 getRows = 0, Int16 getColumns = 0, bool haveTitleRow = true)
        {
            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);
            //記錄每次讀取的一行記錄
            string strLine = "";
            //記錄每行記錄中的各字段內容
            string[] aryLine;
            //標示列數
            int columnCount = 0;
            //是否已創建了表的字段
            bool bCreateTableColumns = false;
            //第幾行
            int iRow = 1;

            //去除無用行
            if (firstRow > 0)
            { 
                for (int i=1; i < firstRow;i++)
                {
                    sr.ReadLine();
                }
            }
            
            // { ",", ".", "!", "?", ";", ":", " " };
            string[] separators = { "," };
            //逐行讀取CSV中的數據
            while ((strLine = sr.ReadLine()) != null)
            {
                strLine = strLine.Trim();
                aryLine = strLine.Split(separators, System.StringSplitOptions.RemoveEmptyEntries);

                if (bCreateTableColumns == false)
                {
                    bCreateTableColumns = true;
                    columnCount = aryLine.Length;
                    //建立列
                    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++)
                {
                    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;
        }
    }
}

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