如何在asp.net C＃4.0中調用異步方法？

Question

我知道.net 4.5有等待，異步關鍵字允許輕松調用異步方法。 我目前正在研究如何在C＃4.0中進行異步調用。 我想要的一個例子是進行異步調用，其中datagrid是數據綁定。

如果你能給我一些鏈接，我會非常感激。

Answer 1

看一下使用任務，這可以在.Net 4中找到並且可以幫到你。 一個簡單的例子可能如下所示：

public void MainFlow()
{
   Task taskWork = Task.Factory.StartNew(new Action(DoWork));
   //Do other work
   //Then wait for thread finish
   taskWork.Wait();
}


private void DoWork()
{
   //Do work
}

有關更多信息，請查看此處

Answer 2

使用Task.ContinueWith，它基本上在任務完成后執行您的操作。

一些可能有用的例子：

http://msdn.microsoft.com/en-us/library/dd784422.aspx

Answer 3

我們為執行異步操作制作了一些工具類。

這些方法實際上做了什么：異步執行操作，然后將completition的執行相應地發布到同步上下文。

我們將其作為TPL的包裝器，以便在我們調用長時間運行操作時輕松使用它。 這個類也有可以取消的行為的類比，而不僅僅是放棄。

public static class AsyncExecutor
    {
        public static CancellationTokenSource ExecuteBlockingOperation(Action action, Action completition, Action<AggregateException> onException)
        {
            if (action == null)
                throw new ArgumentNullException("action");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var cts = new CancellationTokenSource();
            var token = cts.Token;

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task(action, TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPart =>
                                  {
                                      if (!token.IsCancellationRequested)
                                          completition();
                                  },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();

            return cts;

        }

        public static CancellationTokenSource ExecuteBlockingOperation<TIn>(Action<TIn> action, TIn parameter, Action<TIn> completition, Action<AggregateException, TIn> onException)
        {
            if (action == null)
                throw new ArgumentNullException("action");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var cts = new CancellationTokenSource();
            var token = cts.Token;

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task(() => action(parameter), TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception, parameter), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPart =>
                                  {
                                      if (!token.IsCancellationRequested)
                                          completition(parameter);
                                  },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();

            return cts;

        }

        public static CancellationTokenSource ExecuteBlockingOperation<TOut>(Func<TOut> func, Action<TOut> completition, Action<AggregateException> onException)
        {
            if (func == null)
                throw new ArgumentNullException("func");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var cts = new CancellationTokenSource();
            var token = cts.Token;

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task<TOut>(func, TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPart =>
                                  {
                                      if (!token.IsCancellationRequested)
                                          completition(asyncPart.Result);
                                  },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();

            return cts;

        }

        public static CancellationTokenSource ExecuteBlockingOperation<TIn, TOut>(Func<TIn, TOut> func, TIn parameter, Action<TOut, TIn> completition, Action<AggregateException, TIn> onException)
        {
            if (func == null)
                throw new ArgumentNullException("func");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var cts = new CancellationTokenSource();
            var token = cts.Token;

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task<TOut>(() => func(parameter), TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception, parameter), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPart =>
            {
                if (!token.IsCancellationRequested)
                    completition(asyncPart.Result, parameter);
            },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();

            return cts;
        }

        public static CancellationTokenSource ExecuteBlockingOperation<TIn, TOut>(Func<TIn, TOut> func, TIn parameter, Action<TOut> completition, Action<AggregateException, TIn> onException)
        {
            if (func == null)
                throw new ArgumentNullException("func");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var cts = new CancellationTokenSource();
            var token = cts.Token;

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task<TOut>(() => func(parameter), TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception, parameter), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPart =>
            {
                if (!token.IsCancellationRequested)
                    completition(asyncPart.Result);
            },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();

            return cts;
        }

        public static CancellationTokenSource ExecuteBlockingOperation<TIn, TOut>(Func<TIn, TOut> func, TIn parameter, Action<TIn> completition, Action<AggregateException, TIn> onException)
        {
            if (func == null)
                throw new ArgumentNullException("func");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var cts = new CancellationTokenSource();
            var token = cts.Token;

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task<TOut>(() => func(parameter), TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception, parameter), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPart =>
            {
                if (!token.IsCancellationRequested)
                    completition(parameter);
            },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();

            return cts;
        }

        public static CancellationTokenSource ExecuteBlockingOperation<TIn, TOut>(Func<TIn, TOut> func, TIn parameter, Action completition, Action<AggregateException, TIn> onException)
        {
            if (func == null)
                throw new ArgumentNullException("func");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var cts = new CancellationTokenSource();
            var token = cts.Token;

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task<TOut>(() => func(parameter), TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception, parameter), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPart =>
            {
                if (!token.IsCancellationRequested)
                    completition();
            },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();

            return cts;
        }

        public static CancellationTokenSource ExecuteBlockingOperation<TIn, TOut>(Func<TIn, TOut> func, TIn parameter, Action<TIn> completition, Action<AggregateException> onException)
        {
            if (func == null)
                throw new ArgumentNullException("func");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var cts = new CancellationTokenSource();
            var token = cts.Token;

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task<TOut>(() => func(parameter), TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPart =>
            {
                if (!token.IsCancellationRequested)
                    completition(parameter);
            },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();

            return cts;
        }

        public static CancellationTokenSource ExecuteBlockingOperation<TIn, TOut>(Func<TIn, TOut> func, TIn parameter, Action<TOut, TIn> completition, Action<AggregateException> onException)
        {
            if (func == null)
                throw new ArgumentNullException("func");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var cts = new CancellationTokenSource();
            var token = cts.Token;

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task<TOut>(() => func(parameter), TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPart =>
            {
                if (!token.IsCancellationRequested)
                    completition(asyncPart.Result, parameter);
            },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();

            return cts;
        }

        public static CancellationTokenSource ExecuteBlockingOperation<TIn, TOut>(Func<TIn, TOut> func, TIn parameter, Action<TOut> completition, Action<AggregateException> onException)
        {
            if (func == null)
                throw new ArgumentNullException("func");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var cts = new CancellationTokenSource();
            var token = cts.Token;

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task<TOut>(() => func(parameter), TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPart =>
            {
                if (!token.IsCancellationRequested)
                    completition(asyncPart.Result);
            },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();

            return cts;
        }

        public static CancellationTokenSource ExecuteBlockingOperation<TIn, TOut>(Func<TIn, TOut> func, TIn parameter, Action completition, Action<AggregateException> onException)
        {
            if (func == null)
                throw new ArgumentNullException("func");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var cts = new CancellationTokenSource();
            var token = cts.Token;

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task<TOut>(() => func(parameter), TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPart =>
            {
                if (!token.IsCancellationRequested)
                    completition();
            },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();

            return cts;
        }

        public static void ExecuteBlockingOperation(Action action, Action completition, Func<bool> shouldComplete, Action<AggregateException> onException)
        {
            if (action == null)
                throw new ArgumentNullException("action");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task(action, TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPart =>
                                  {
                                      if (shouldComplete == null || shouldComplete())
                                          completition();
                                  },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();
        }

        public static void ExecuteBlockingOperation<TIn>(Action<TIn> action, TIn parameter, Action<TIn> completition, Predicate<TIn> shouldComplete, Action<AggregateException, TIn> onException)
        {
            if (action == null)
                throw new ArgumentNullException("action");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task(() => action(parameter), TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception, parameter), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPart =>
                                  {
                                      if (shouldComplete == null || shouldComplete(parameter))
                                          completition(parameter);
                                  },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();
        }

        public static void ExecuteBlockingOperation<TOut>(Func<TOut> func, Action<TOut> completition, Predicate<TOut> shoudComplete, Action<AggregateException> onException)
        {
            if (func == null)
                throw new ArgumentNullException("func");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task<TOut>(func, TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler);
            task.ContinueWith(asyncPartTask =>
                                  {
                                      if (shoudComplete == null || shoudComplete(asyncPartTask.Result))
                                          completition(asyncPartTask.Result);
                                  },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();
        }

        public static void ExecuteBlockingOperation<TIn, TOut>(Func<TIn, TOut> func, TIn parameter, Action<TOut, TIn> completition, Func<TOut, TIn, bool> shouldComplete, Action<AggregateException, TIn> onException)
        {
            if (func == null)
                throw new ArgumentNullException("func");

            if (completition == null)
                throw new ArgumentNullException("completition");

            var scheduler = TaskScheduler.FromCurrentSynchronizationContext();

            var task = new Task<TOut>(() => func(parameter), TaskCreationOptions.LongRunning);
            task.ContinueWith(asyncPartTask => onException(asyncPartTask.Exception, parameter), CancellationToken.None, TaskContinuationOptions.OnlyOnFaulted, scheduler); // on Exception
            task.ContinueWith(asyncPart =>
                                  {
                                      if (shouldComplete == null || shouldComplete(asyncPart.Result, parameter))
                                          completition(asyncPart.Result, parameter);
                                  },
                              CancellationToken.None, TaskContinuationOptions.OnlyOnRanToCompletion, scheduler);
            task.Start();
        }            
    }