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();
}
}
}