本地文件日志，LocalLog.cs

    /// <summary>
    /// 本地文件日志
    /// </summary>
    public class LocalLog
    {
        private static object _obj = new object();
        private const string LOG_FILE = @"log.txt";

        /// <summary>
        /// 添加本地日志
        /// </summary>
        /// <param name="log"></param>
        public static void AddLog(string log)
        {
            Task.Run(() =>
            {
                lock (_obj)//避免多线程占用文件
                {
                    log = DateTime.Now.ToString("yyyy-MM-dd HH:mm:ss:fff") + "\r\n" + log;
                    FileStream fs = null;
                    try
                    {
                        string binPath = Assembly.GetExecutingAssembly().Location;
                        binPath = Path.GetDirectoryName(binPath);
                        string fileName = Path.Combine(binPath, LOG_FILE);
                        fs = File.Open(fileName, FileMode.OpenOrCreate);
                        if (fs.Length > 0) log = "\r\n" + log;//加断行符
                        byte[] bs = Encoding.UTF8.GetBytes(log);
                        fs.Seek(fs.Length, SeekOrigin.Begin);
                        fs.Write(bs, 0, bs.Length);
                        fs.Flush();
                        fs.Close();
                        fs.Dispose();
                    }
                    catch
                    {
                        if (fs != null)
                        {
                            fs.Close();
                            fs.Dispose();
                        }
                    }
                }
            });
        }
    }