Task

http://www.cnblogs.com/czllfy/archive/2011/04/15/2016733.html

　　　　　　　　//没有返回值
            //定义 Task StartNew(Action action);
　　　　　　　//Task.Factory.StartNew 相当于Task.Run

            var t1 = Task.Factory.StartNew(() => Console.WriteLine("Task Created!"));
            Console.WriteLine(t1.Status);

            //有返回值
            //定义 Task<TResult> StartNew<TResult>(Func<TResult> function);
            var task = Task.Factory.StartNew<string>(() => "Task Created!");
            Console.WriteLine(task.Result);
            Console.WriteLine(t1.Status);

            Console.WriteLine(t1.Status);





            var task = new Task<string>(() => "Task Created!");
            Console.WriteLine(task.Status);
            task.Start();//异步执行
            Console.WriteLine(task.Status);
            Console.WriteLine(task.Result);
            Console.WriteLine(task.Status);

            var task = new Task<string>(() => "Task Created!");
            task.RunSynchronously();//同步执行
            Console.WriteLine(task.Result);

            var task = Task.Factory.StartNew(state => "hello " + state, "Mike");
            Console.WriteLine(task.AsyncState);
            Console.WriteLine(task.Result);


            var tasks = new Task[3];
            for (int i = 0; i < tasks.Length; i++)
            {
                int taskIndex = i;
                tasks[i] = Task.Factory.StartNew(() =>
                {
                    int seed = Guid.NewGuid().GetHashCode();
                    int waitTime = new Random(seed).Next(10, 100);
                    Thread.Sleep(waitTime);
                    Console.WriteLine("Task{0} Finished", taskIndex);
                });
            }
            Task.WaitAny(tasks);//等待某一个任务完成
            Console.WriteLine("已有任务完成");

　　　　　static void GetUrlLength(string result)
        {
            Console.WriteLine("现在时间为："+DateTime.Now.Ticks + ",长度为：" + result.Length);
        }

        static void AccessUrlForNet5Async()
        {
            var client = new WebClient();
            //原型为 Task<string> DownloadStringTaskAsync(string address);
            var w1 = client.DownloadStringTaskAsync("http://msdn.microsoft.com/zh-tw").GetAwaiter();
            w1.OnCompleted(() =>
            {
                GetUrlLength(w1.GetResult());
            });

            //GetUrlLength(await client.DownloadStringTaskAsync("http://msdn.microsoft.com/"));

        }

            var client = new WebClient();
            var t1 = client.DownloadStringTaskAsync("http://msdn.microsoft.com/zh-tw");
            t1.ContinueWith(t =>
            {
                GetUrlLength(t1.Result);
            });

Task<int> task = Task.Run(() =>Enumerable.Range(1,500000).Count(n=>(n%3)==0));
Console.WriteLine("500000以内 能整除3的个数有：" + task.Result);//task未完成时，查询Result会封锁当前线程

public static void Main()
   {
        Task<Double>[] taskArray = { Task<Double>.Factory.StartNew(() => DoComputation(1.0)),
                                     Task<Double>.Factory.StartNew(() => DoComputation(100.0)), 
                                     Task<Double>.Factory.StartNew(() => DoComputation(1000.0)) };

        var results = new Double[taskArray.Length];
        Double sum = 0;
        
        for (int i = 0; i < taskArray.Length; i++) {
            results[i] = taskArray[i].Result;
            Console.Write("{0:N1} {1}", results[i], 
                              i == taskArray.Length - 1 ? "= " : "+ ");
            sum += results[i];
        }
        Console.WriteLine("{0:N1}", sum);
   }

   private static Double DoComputation(Double start)
   {
      Double sum = 0;
      for (var value = start; value <= start + 10; value += .1)
         sum += value;

      return sum; 
   }