C#中一道关于线程同步的练习题——模拟多窗口售票

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Threading;
using System.IO;
using System.Reflection;
using System.Diagnostics;

namespace SellTicketsSynchronously
{
    class Program
    {
        //入口
        static void Main(string[] args)
        {
            Ticket tc = new Ticket(10);
            Thread sellWindowA = new Thread(new ParameterizedThreadStart(SellTicket));
            Thread sellWindowB = new Thread(new ParameterizedThreadStart(SellTicket));
            Thread sellWindowC = new Thread(new ParameterizedThreadStart(SellTicket));
            Thread sellWindowD = new Thread(new ParameterizedThreadStart(SellTicket));
            sellWindowA.Name = "Window A";
            sellWindowB.Name = "Window B";
            sellWindowC.Name = "Window C";
            sellWindowD.Name = "Window D";
            sellWindowA.Start(tc);
            sellWindowB.Start(tc);
            sellWindowC.Start(tc);
            sellWindowD.Start(tc);
            sellWindowA.Join();
            sellWindowB.Join();
            sellWindowC.Join();
            sellWindowD.Join();
            Console.WriteLine("Tickets has been sold out. Press any key to quit:");
            Console.ReadLine();
        }
        //卖票方法
        public static void SellTicket(object obj) 
        {
            Ticket ticket = obj as Ticket;
            while (ticket.NumOfTickets>0)
            {
                lock (ticket)
                {
                    if (ticket.NumOfTickets > 0)
                    {
                        try
                        {
                            ticket.NumOfTickets--;
                            Console.WriteLine( DateTime.Now.ToString()+":"+Thread.CurrentThread.Name + " sells a ticket, " + ticket.NumOfTickets + " tickets left.");
                        }
                        catch (Exception ex)
                        {
                            WriteLog(ex);
                        }
                    }
                }
                Random random = new Random();
                Thread.Sleep(random.Next(100,500));
            } 
        }
        //打log方法
        private static void WriteLog(Exception ex)
        {
            string logUrl = Environment.GetFolderPath(Environment.SpecialFolder.DesktopDirectory) + "\\SellTicketslog.txt";
            if (File.Exists(@logUrl))
            {
                using (FileStream fs = new FileStream(logUrl, FileMode.Append))
                {
                    using (StreamWriter sw = new StreamWriter(fs, Encoding.Default))
                    {
                        try
                        {
                            sw.Write(ex);
                        }
                        catch (Exception ex1)
                        {
                            WriteLog(ex1);
                        }
                        finally
                        {
                            sw.Close();
                            fs.Close();
                        }
                    }
                }
            }
            else
            {
                using (FileStream fs = new FileStream(logUrl, FileMode.CreateNew))
                {
                    using (StreamWriter sw = new StreamWriter(fs, Encoding.Default))
                    {
                        try
                        {
                            sw.Write(ex);
                        }
                        catch (Exception ex1)
                        {
                            WriteLog(ex1);
                        }
                        finally
                        {
                            sw.Close();
                            fs.Close();
                        }
                    }
                }
            }
        }
    }
    //票类
    class Ticket 
    {
        public int NumOfTickets { get; set; }
        public Ticket(int num) 
        {
            this.NumOfTickets = num;
        }
    }
}