C# 任务的异常和延续处理

写在前面

当Task在执行过程中出现异常或被取消等例外的情况时，为了让执行流程能够继续进行，可以使用延续方法实现这种链式处理；还可以针对前置任务不同的执行结果，选择执行不同的延续分支方法。子任务执行过程中的任何异常都会被传递到延续方法中进行统一处理，因此而增强了对并行任务的流程控制。

代码实现

        public static void ContinueWithException()
        {
            TaskCreationOptions tco = TaskCreationOptions.AttachedToParent;
            Task task = Task.Factory.StartNew(() =>
            {
                Task.Factory.StartNew(() => { throw new Exception(Environment.NewLine + "first exception" + Environment.NewLine); }, tco);
                Task.Factory.StartNew(() => { throw new Exception(Environment.NewLine + "second exception" + Environment.NewLine); }, tco);
                Task.Factory.StartNew(() => { throw new Exception(Environment.NewLine + "third exception" + Environment.NewLine); }, tco);
            }).ContinueWith(t => Console.WriteLine("Message:" + t.Exception.Message + Environment.NewLine), TaskContinuationOptions.OnlyOnFaulted);
            task.Wait();


            Task task01 = Task.Factory.StartNew(() =>
            {
                Console.WriteLine("task01 executed.");
            });
            Task ok1 = task01.ContinueWith(t => Console.WriteLine("Ok"), TaskContinuationOptions.NotOnFaulted);
            Task fail1 = task01.ContinueWith(t => Console.WriteLine("Failure:" + t.Exception.Message), TaskContinuationOptions.OnlyOnFaulted);

            Task task02 = Task.Factory.StartNew(() =>
            {
                throw new Exception("task02 executed.");
            });
            Task ok2 = task02.ContinueWith(t => Console.WriteLine("Ok"), TaskContinuationOptions.NotOnFaulted);
            Task fail2 = task02.ContinueWith(t => Console.WriteLine("Failure:" + t.Exception.Message), TaskContinuationOptions.OnlyOnFaulted);

        }