Task取消以及异常处理

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using System;

using System.Threading;

using System.Threading.Tasks;

 

namespace ConsoleApp1

{

    public class TaskCancelTest

    {

        //测试Task取消以及异常处理

        public static void RunTest()

        {

            CancellationTokenSource cts = new CancellationTokenSource();

            ParamCls paramCls = new ParamCls { token = cts.Token, n = 1000 };

            //注意，此处调用多个参数的两种写法：

            Task<Int32> t = new Task<int>(() => OpWithParamIntAndReturnInt(cts.Token, 1000), cts.Token);

            Task<Int32> t1 = new Task<int>(o => OpWithParamIntAndReturnInt2((ParamCls)o), paramCls,cts.Token);

 

            t.Start();

            //t1.Start();

 

            //取消任务，这是一个异步操作，Task可能已经完成了

            cts.Cancel();

 

            try

            {

                //如果任务已经取消了，Result会抛出一个AggregateException

                Console.WriteLine("The result is:"+t.Result.ToString());

            }

            catch(AggregateException ex)

            {

                //将任何的OperationCanceledException对象都视为已处理。

                //其他任何异常都造成抛出一个新的AggregateException，其中只包含未处理的异常。

                ex.Handle(a => a is OperationCanceledException);

 

                //所有异常都处理好之后，执行下面这一行

                Console.WriteLine("The Task was canceled.");

            }

 

        }

 

        private static Int32 OpWithParamIntAndReturnInt(CancellationToken ct, Int32 state)

        {

            Console.WriteLine("In OpWithParamIntAndReturnInt,state=" + state.ToString());

 

            //在取消标志引用的CancellationTokenSource上，如果调用Cancel，下面这一行会抛出OperationCanceledException

            ct.ThrowIfCancellationRequested();

 

            Thread.Sleep(1000);

            return state;

        }

 

        private static Int32 OpWithParamIntAndReturnInt2(ParamCls paramCls)

        {

            Console.WriteLine("In OpWithParamIntAndReturnInt2,state=" + paramCls.n.ToString());

 

            //在取消标志引用的CancellationTokenSource上，如果调用Cancel，下面这一行会抛出OperationCanceledException

            paramCls.token.ThrowIfCancellationRequested();

 

            Thread.Sleep(1000);

            return paramCls.n;

        }

 

        class ParamCls

        {

            public CancellationToken token { get; set; }

            public int n { get; set; }

        }

    }

}