CancellationTokenSource 和 CancellationToken 取消线程

Main 程序[分别调用三个方法]

 static void Main(string[] args)
        {
            using (CancellationTokenSource cts = new CancellationTokenSource())
            {
                CancellationToken token = cts.Token;
                ThreadPool.QueueUserWorkItem(p => AsyncOperation(token));
                Thread.Sleep(TimeSpan.FromSeconds(2));
                cts.Cancel();
            };

            //休眠两秒，否则主线程结束了，新的线程也会结束
            Thread.Sleep(TimeSpan.FromSeconds(2));
        }

方法一

 static void AsyncOperation(CancellationToken token)
        {
            Console.WriteLine("开始第一个任务");
            for (int i = 0; i < 5; i++)
            {
                if (token.IsCancellationRequested)
                {
                    Console.WriteLine(i + ":" + token.IsCancellationRequested.ToString());
                    return;
                }
                else
                {
                    Console.WriteLine(i + ":" + token.IsCancellationRequested.ToString());
                }
                  
                Thread.Sleep(TimeSpan.FromSeconds(1));
            }
            Console.WriteLine("任务执行完成");
        }

运行结果

方法二

 static void AsyncOperation2(CancellationToken token)
        {
            try
            {
                Console.WriteLine("开始第二个任务");
                for (int i = 0; i < 5; i++)
                {
                    token.ThrowIfCancellationRequested();
                    Thread.Sleep(TimeSpan.FromSeconds(1));
                    Console.WriteLine("第二个任务执行完成");
                }
            }
            catch (OperationCanceledException ex)
            {
                Console.WriteLine("第二个任务被取消了");
            }
        }

运行结果：

方法三

  static void AsyncOperation3(CancellationToken token)
        {
            bool cancelflag = false;
            token.Register(() => cancelflag = true);//被取消时cancelflag会设置为True
            Console.WriteLine("开始第三个任务");
            for (int i = 0; i < 5; i++)
            {
                if (cancelflag == true)
                {
                    Console.WriteLine("第三个任务被取消了");
                    return;
                }
                else
                {
                    Console.WriteLine(i + ":" + token.IsCancellationRequested.ToString());
                }
                Thread.Sleep(TimeSpan.FromSeconds(1));
            }
            Console.WriteLine("第三个任务执行完成");

        }

运行结果：