如何用C#以最简方式读取dbase4编码文件？OleDB方案报错

问题背景 #

• 从西门子CNC控制系统840D powerline导出的机床数据为dBase IV格式，直接读取仅能识别ASCII字符，非ASCII特殊字符无法正常解析
• 尝试使用OleDB方案读取时触发平台不支持异常，错误信息如下：

OdebD Error  System.TypeInitializationException: The type initializer for   'System.Data.OleDb.OleDbConnection' threw an exception.
---> System.TypeInitializationException: The type initializer for   'System.Data.OleDb.OleDbConnectionFactory' threw an exception.
---> System.TypeInitializationException: The type initializer for 'System.Data.ProviderBase.DbConnectionPoolCountersNoCounters' threw an exception.
---> System.TypeInitializationException: The type initializer for 'CreationData' threw an   exception.
---> System.PlatformNotSupportedException: Performance Counters are not supported on this platform.
at System.Diagnostics.CounterCreationData..ctor(String counterName, String counterHelp, PerformanceCounterType counterType)
at System.Data.ProviderBase.DbConnectionPoolCounters.CreationData..cctor()
--- End of inner exception stack trace ---
at System.Data.ProviderBase.DbConnectionPoolCounters..ctor(String categoryName, String categoryHelp)
at System.Data.ProviderBase.DbConnectionPoolCounters..ctor()
at System.Data.ProviderBase.DbConnectionPoolCountersNoCounters..ctor()
at System.Data.ProviderBase.DbConnectionPoolCountersNoCounters..cctor()
--- End of inner exception stack trace ---
at System.Data.ProviderBase.DbConnectionFactory..ctor()
at System.Data.OleDb.OleDbConnectionFactory..ctor()
at System.Data.OleDb.OleDbConnectionFactory..cctor()
  --- End of inner exception stack trace ---
at System.Data.OleDb.OleDbConnection..cctor()
--- End of inner exception stack trace ---
at System.Data.OleDb.OleDbConnection.get_ConnectionFactory()
at System.Data.OleDb.OleDbConnection.ConnectionString_Set(DbConnectionPoolKey key)
at System.Data.OleDb.OleDbConnection.ConnectionString_Set(String value)
at System.Data.OleDb.OleDbConnection.set_ConnectionString(String value)
at System.Data.OleDb.OleDbConnection..ctor(String connectionString)
at WebApplication7.Pages.PLC_Var.dbase() in C:\01_md9bu_Projects\ASP\WebApplication7\Pages\PLC_Var.razor.cs:line 37010/1/2022 1:57:22 PM

• 原尝试的OleDB代码：

public void dbase()
{
    try
    {
        string constr = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=C:\\test;Extended Properties=dBASE IV;User ID=Admin;Password=;";
        using (OleDbConnection con = new OleDbConnection(constr))
        {
            var sql = "select * from " + "NC_MD_ACC";
            OleDbCommand cmd = new OleDbCommand(sql, con);
            con.Open();
            DataSet ds = new DataSet(); ;
            OleDbDataAdapter da = new OleDbDataAdapter(cmd);
            da.Fill(ds);
            Deltalogic.NC_VAR_test_string = ds.Tables[0].ToString();
            using (StreamWriter sw = File.AppendText(CommonClass.error_path))
            {
                sw.WriteLine("OdebD OK  " + Convert.ToString(DateTime.Now));
            }
        }
    }

    catch (Exception e)
    {
        using (StreamWriter sw = File.AppendText(CommonClass.error_path))
        {
            sw.WriteLine("OdebD Error  " + e + Convert.ToString(DateTime.Now));
        }

    }
}

最简可行方案：使用DbfDataReader库 #

OleDB方案失败的原因是Microsoft.Jet.OLEDB.4.0是老旧的Windows专属驱动，在.NET Core/.NET 5+等现代平台中不支持性能计数器，导致初始化异常。推荐使用专门的dBase文件读取库DbfDataReader，它跨平台、轻量且支持指定编码解决特殊字符问题。

步骤1：安装NuGet包 #

在项目中安装DbfDataReader：

Install-Package DbfDataReader
# 或者使用.NET CLI
dotnet add package DbfDataReader

步骤2：编写读取代码 #

西门子840D导出的dBase IV文件通常使用OEM编码（如CP850），需指定对应编码以正确解析特殊字符：

using DbfDataReader;
using System.Text;
using System.Linq;

public void ReadDbaseFile()
{
    try
    {
        // 指定dBase文件路径
        var dbfPath = @"C:\test\NC_MD_ACC.dbf";
        // 西门子常用编码为CP850，可根据实际情况调整
        var encoding = Encoding.GetEncoding(850);

        using (var dbfReader = new DbfReader(dbfPath, encoding))
        {
            // 获取所有列名
            var columns = dbfReader.Columns.Select(c => c.Name).ToList();
            // 逐行读取数据
            while (dbfReader.Read())
            {
                // 拼接当前行的字段信息
                var rowContent = string.Join(", ", columns.Select(col => $"{col}: {dbfReader[col]}"));
                Deltalogic.NC_VAR_test_string += rowContent + Environment.NewLine;
            }
        }

        using (StreamWriter sw = File.AppendText(CommonClass.error_path))
        {
            sw.WriteLine("DbfDataReader OK  " + DateTime.Now.ToString());
        }
    }
    catch (Exception e)
    {
        using (StreamWriter sw = File.AppendText(CommonClass.error_path))
        {
            sw.WriteLine("DbfDataReader Error  " + e + " " + DateTime.Now.ToString());
        }
    }
}

关键说明 #

• 编码选择：如果CP850无法正确解析，可尝试Encoding.GetEncoding(1252)（Windows-1252）或西门子机床对应的其他OEM编码
• 该库支持dBase IV、dBase III等多种格式，无需依赖OleDB驱动，兼容.NET Framework/.NET Core/.NET 5+所有平台

内容的提问来源于stack exchange，提问作者Mdarende