多线程操作同一文件进行读写

通过锁方式，只能允许单个线程操作文件，避免同时操作同一文件造成“由于另一进程正在访问...”的错误

public class LogServices
    {

        private static LogServices _instance;
        private static readonly object _lock = new object();
        private static readonly object _lockFile=new object();
        private LogServices()
        {

        }
        public static LogServices Instance()
        {
            if (_instance == null) 
            {
                lock (_lock)
                {
                    if (_instance == null)
                    {
                        _instance = new LogServices();
                        return _instance;
                    }
                    else{
                      return _instance;
                    }
                }
            }
            else
            {
                return _instance;
            }
        }

        public bool GenerateLogFile(string strText, string folder = "")
        {
            //lock (_lockFile)
            {
                string filePath = Path.Combine(Directory.GetCurrentDirectory(), "Log");
                bool bresult = false;
                string currentDate = DateTime.Now.ToString("yyyyMMdd");
                string currentTime = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss");
                if (filePath.Length <= 0)
                    return bresult;
                else
                {
                    filePath = string.IsNullOrWhiteSpace(folder) ? filePath : Path.Combine(filePath, folder);
                    lock (_lockFile)
                    {
                        //路径不存在则创建路径
                        if (!Directory.Exists(filePath))
                        {
                            Directory.CreateDirectory(filePath);
                        }
                        filePath = Path.Combine(filePath, currentDate + folder + ".txt");
                        //文件不存在则生成文件
                        if (!File.Exists(filePath))
                        {
                            File.Create(filePath).Close();
                        }
                        StreamWriter sw = new StreamWriter(filePath, true, System.Text.Encoding.Default);//第一个参数代表路径，第二个参数表示文件是否覆盖还是在原有文件基础上添加，第三个参数代表编码格式
                        sw.WriteLine(currentTime + ":" + strText);//写入txt文件
                        bresult = true;
                        sw.Flush();
                        sw.Close();
                    }
                    


                }
                return bresult;
            }
        }

    }