Task是.net 4.0中的一个新特性,提供的功能非常强大,下面是其具体的使用方法演示:
using System; using System.Threading.Tasks; using System.Threading; namespace ConsoleApplication1 { class Program { static void Main(string[] args) { RunnerRaceTest(); Console.WriteLine("into main loop now..."); Console.ReadLine(); } static void RunnerRaceTest() { Task[] tRunners = new Task[10]; for (int i = 0; i < 10; i++) { Console.WriteLine("我是运动员" + i.ToString() + "号，我已经就位"); tRunners[i] = new Task(() => { }); } Console.WriteLine("预备开始，跑..."); Parallel.ForEach(tRunners, i => { i.Start(); Thread.Sleep(2000); Console.WriteLine(i.Id.ToString() + "号运动员已经到达..."); }); Task.WaitAll(tRunners); Console.WriteLine("比赛完毕..."); } //handle ContinueWith method. //TaskContinuationOptions.OnlyOnRanToCompletion means that //only the first task runs successfully, then the continue one will start to run. //ContinueWith的使用方法 /*******运行结果(当第一个TaskContinuationOptions.OnlyOnRanToCompletion时)********* * this is an exception * into main loop now... **********************/ /*******运行结果(当第一个TaskContinuationOptions.OnlyOnFaulted时)********* * exception found in prev task when handling Continuation... * this is continuation... * this is an exception * into main loop now... **********************/ static void TaskContinueWith() { Task t1 = new Task(() => { throw new Exception("this is an exception"); Console.WriteLine("this is task one..."); }); Task t2 = t1.ContinueWith((preTask) => { if (preTask.Exception != null) { Console.WriteLine("exception found in prev task when handling Continuation..."); } Console.WriteLine("this is continuation..."); },TaskContinuationOptions.AttachedToParent|TaskContinuationOptions.OnlyOnFaulted); t1.Start(); try { t1.Wait(); t2.Wait(); } catch (AggregateException e) { Console.WriteLine(e.InnerException.Message); } } //handle children tasks //主要是用来测试子任务的运行，利用AttachedToParent来实现子任务功能 /*******运行结果********* * into the first task now... * into the second task now... * into the third task now... * Exception caught :GrandChild exception * into main loop now... **********************/ static void TaskWithChildren() { Task t = new Task(() => //主任务 { Console.WriteLine("into the first task now..."); Task childTask = new Task(() => //第一个子任务 { Console.WriteLine("into the second task now..."); Task grandChildTask = new Task(() => //第二个子任务 { Console.WriteLine("into the third task now..."); throw new Exception("GrandChild exception"); }, TaskCreationOptions.AttachedToParent); grandChildTask.Start(); //开始第二个子任务 }, TaskCreationOptions.AttachedToParent); childTask.Start(); //开始第一个子任务 }); t.Start(); //开启主任务 try { t.Wait(); //同步运行等待 } catch (AggregateException e) { Console.WriteLine("Exception caught : " + e.InnerException.InnerException.InnerException.Message); } } //handle cancellation during task running //主要用来测试任务执行过程中的取消操作 /*******运行结果********* * this is task iteration 1 * the operation has been canceled... * into main loop now... **********************/ static void TaskWithCancellation() { CancellationTokenSource cancellationTokenSource = new CancellationTokenSource(); CancellationToken cancellationToken = cancellationTokenSource.Token; //主要用于任务取消操作的信号量设置 Task t = new Task(() => { int i = 0; while (true) { i++; Thread.Sleep(1000); Console.WriteLine("this is task iteration " + i); cancellationToken.ThrowIfCancellationRequested(); //注册信号量，如果用户取消，那么将会中断在此处 Console.WriteLine("Test to see if below can be excuted..."); Console.WriteLine("I am not excute"); } }, cancellationToken); t.Start(); //开始任务 Thread.Sleep(1000); cancellationTokenSource.Cancel(); //取消任务 try { t.Wait(); } catch (AggregateException e) { if (e.InnerException is OperationCanceledException) Console.WriteLine("the opeartion has been canceled..."); else Console.WriteLine("encounter some unexpected exceptions..."); } } //handle timeout in task running //主要是用来测试任务执行的超时功能 /*******运行结果********* * We are waiting for the task to finish * the task has timed out. * into main loop now... * I started... * *********************/ static void TaskWithTimeout() { Task t = new Task(() => { Thread.Sleep(3000); Console.WriteLine("I started..."); }); t.Start(); //开始任务 Console.WriteLine("We are waiting for the task to finish"); //任务执行的超时时间为２s，程序执行需要3s，所以会出现超时 bool hasNotTimeOut = t.Wait(2000); if (hasNotTimeOut) Console.WriteLine("the task has not timed out."); else Console.WriteLine("the task has timed out."); } //handle exception during task execution. //主要是用来测试任务执行时候的错误捕获功能 /*******运行结果********* * We are waiting for the task to finish * Caught Exception:this is exception in task... * into main loop now... * *********************/ static void TaskWithException() { Task t = new Task(() => { throw new Exception("this is exception in task..."); //当任务执行的时候，出现了Exception Console.WriteLine("I started.."); }); t.Start(); //开始运行任务 Console.WriteLine("We are waiting for the task to finish"); try { t.Wait(); //同步执行 } catch (AggregateException e) //AggregateException可以捕获运行中出现的错误 { Console.WriteLine("Caught Exception:" + e.InnerException.Message); //这里显示 } } //simple use of Task //主要是介绍Task的最简单用法 /*******运行结果********* * started... * into main loop now... * *********************/ static void TaskOfFirst() { Task t = new Task(() => { Console.WriteLine("I started..."); }); //开始运行 t.Start(); //等待任务运行完成，这里将会阻塞主线程，如果去掉，那么主线程和子线程会并行运行 t.Wait(); } } }
