C#常用多线程方法

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1. Thread类

C#多线程编程中Thread类需要包含名称空间System.Threading。

class Program    {        static void Main(string[] args)        {            Thread thread01 = new Thread(ThreadTask01);            thread01.Start();           // thread01.Join();            for (int i = 0; i < 5; i++)            {                Console.WriteLine("Thread Main is working !");                Thread.Sleep(20);            }            Console.ReadKey();        }        static void ThreadTask01()        {            for (int i = 0; i < 5; i++)            {                Console.WriteLine("Thread task one is working !");                Thread.Sleep(20);            }        }    }

输出：

Start不会阻塞主线程，如果加入Join，则会阻塞主线程的执行，直到子线程执行完成才把控制权交还给主流程，但是各个子线程之间的并行执行不受Join影响。上例中加入Join的输出：

多个线程同时访问一个公共字段时，容易引起线程安全问题，C#中使用关键字lock保证数据的安全性和同步：

class Program    {        //static readonly object locker = new object();        static int TotalNum = 100;        static void Main(string[] args)        {            Thread thread01 = new Thread(ThreadTask01);            Thread thread02 = new Thread(ThreadTask02);            thread01.Start();            thread02.Start();            Console.ReadKey();        }        static void ThreadTask01()        {            while (TotalNum > 0)            {                Console.WriteLine(TotalNum);                TotalNum--;                Thread.Sleep(10);            }        }        static void ThreadTask02()        {            while (TotalNum > 0)            {                Console.WriteLine(TotalNum);                TotalNum--;                Thread.Sleep(10);            }        }    }

输出异常，中间有重复输出的数字：

添加lock：

class Program    {        static readonly object locker = new object();        static int TotalNum = 100;        static void Main(string[] args)        {            Thread thread01 = new Thread(ThreadTask01);            Thread thread02 = new Thread(ThreadTask02);            thread01.Start();            thread02.Start();            Console.ReadKey();        }        static void ThreadTask01()        {            while (TotalNum > 0)            {                lock (locker)                {                    Console.WriteLine(TotalNum);                    TotalNum--;                }                Thread.Sleep(10);            }        }        static void ThreadTask02()        {            while (TotalNum > 0)            {                lock (locker)                {                    Console.WriteLine(TotalNum);                    TotalNum--;                }                Thread.Sleep(10);            }        }    }

输出正常：

2. ParameterThreadStart委托

ParameterThreadStart委托定义为 void ParameterizedThreadStart(Object state)。

class Program    {        static int totalNum = 10;        static void Main(string[] args)        {            ParameterizedThreadStart thread01 = new ParameterizedThreadStart(ThreadTask01);            Thread thread = new Thread(thread01);            thread.Start(totalNum);            Console.ReadKey();        }        static void ThreadTask01(object obj)        {            for (int i = 0; i < Convert.ToInt32(obj); i++)            {                Console.WriteLine(i);                Thread.Sleep(10);            }        }    }

3. 匿名方法

匿名方法启动多线程是使用Thread类的另一种更加灵活的方法。

class Program    {        static void Main(string[] args)        {            ThreadStart threadStart = new ThreadStart(delegate ()              {                  for (int i = 0; i < 5; i++)                  {                      Console.WriteLine("Thread one is working!");                  }              });            Thread thread = new Thread(threadStart);            thread.Start();//多线程启动匿名方法            //等待线程结束                        while (thread.ThreadState != ThreadState.Stopped)            {                Thread.Sleep(10);            }            Console.ReadKey();        }    }

4. Delegate委托

委托是一种比较高级的多线程方法，可以传入参数和获取返回值，还可以查询异步操作是否完成。

class Program    {        private delegate int NewTaskDelegate(int ms);        private static int newTask(int ms)        {            Console.WriteLine("任务开始");            Thread.Sleep(ms);            Random random = new Random();            int n = random.Next(10000);            Console.WriteLine("任务完成");            return n;        }        static void Main(string[] args)        {            NewTaskDelegate task = newTask;            IAsyncResult asyncResult = task.BeginInvoke(2000, null, null);            //EndInvoke方法将被阻塞2秒            //使用WaitOne阻塞主线程，直到子线程完成操作            while (!asyncResult.AsyncWaitHandle.WaitOne(100, false))            {                Console.Write("-");            }            while (!asyncResult.IsCompleted)  //查询线程是否完成            {                Console.Write("*");                Thread.Sleep(100);            }            int result = task.EndInvoke(asyncResult);            Console.WriteLine(result);            Console.Read();        }    }

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