C#读取远程CNC机器IPC文件提示被占用的解决方法

问题核心在于File.ReadAllLines默认会以独占访问模式打开文件，而CNC机器写入该文件时可能未允许共享读取，导致代码报错。手动打开文件（如记事本、资源管理器）之所以正常，是因为这些工具默认使用允许共享的文件访问模式。

修改后的代码 #

public void Read_Alarm_Log_File()
{
    string networkPath = "\\\\" + TagService.IP_Win_List + "\\F$";
    string filePath = Path.Combine(networkPath, "mmc2", "proto.txt");
    NetworkCredential credentials = new NetworkCredential("username", "XXXXX");

    TagService.Alarm_log_File_content.Clear();

    try
    {
        using (new NetworkConnection(networkPath, credentials))
        {
            // 以允许共享读写的模式打开文件，避免独占冲突
            using (var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
            using (var streamReader = new StreamReader(fileStream))
            {
                string line;
                while ((line = streamReader.ReadLine()) != null)
                {
                    TagService.Alarm_log_File_content.Add(line + "\n");
                }
            }
        }
    }
    catch (Exception ex)
    {
        using (StreamWriter sw = File.AppendText(CommonClass.error_path))
        {
            sw.WriteLine($"Alarm Log File could not be read: {ex} {DateTime.Now}");
        }
    }
}

关键改动说明 #

• 用FileStream手动指定文件访问参数：FileShare.ReadWrite允许其他进程同时读取或写入该文件，避免独占锁冲突。
• 使用StreamReader逐行读取，和原代码逻辑一致，但更灵活控制文件打开模式。
• 用Path.Combine拼接路径，避免手动拼接字符串可能出现的格式错误。

额外建议 #

如果偶尔还是出现读取失败，可以添加重试机制，因为CNC写入文件的时间很短，重试大概率能成功：

public void Read_Alarm_Log_File()
{
    string networkPath = "\\\\" + TagService.IP_Win_List + "\\F$";
    string filePath = Path.Combine(networkPath, "mmc2", "proto.txt");
    NetworkCredential credentials = new NetworkCredential("username", "XXXXX");

    TagService.Alarm_log_File_content.Clear();
    int retryCount = 3;

    try
    {
        using (new NetworkConnection(networkPath, credentials))
        {
            while (retryCount > 0)
            {
                try
                {
                    using (var fileStream = new FileStream(filePath, FileMode.Open, FileAccess.Read, FileShare.ReadWrite))
                    using (var streamReader = new StreamReader(fileStream))
                    {
                        string line;
                        while ((line = streamReader.ReadLine()) != null)
                        {
                            TagService.Alarm_log_File_content.Add(line + "\n");
                        }
                    }
                    break; // 读取成功，跳出重试循环
                }
                catch (IOException) when (retryCount > 1)
                {
                    retryCount--;
                    Thread.Sleep(1000); // 等待1秒后重试
                }
            }
        }
    }
    catch (Exception ex)
    {
        using (StreamWriter sw = File.AppendText(CommonClass.error_path))
        {
            sw.WriteLine($"Alarm Log File could not be read: {ex} {DateTime.Now}");
        }
    }
}

内容的提问来源于stack exchange，提问作者Mdarende