## 对连续的异步任务使用await操作符 ```csharp /// <summary> /// 对连续的异步任务使用await操作符 /// </summary> /// <param name="args"></param> static void Main(string[] args) { Task t = AsynchronyWithTPL(); t.Wait(); t = AsynchronyWithAwait(); t.Wait(); Console.ReadLine(); } /// <summary> /// 使用TPL方式的实现 /// 功能等同于AsynchronyWithAwait方法的功能 /// 但是写法复杂很多 /// </summary> /// <returns></returns> static Task AsynchronyWithTPL() { var containerTask = new Task(() => { Task<string> t = GetInfoAsync("TPL 1"); t.ContinueWith(task => { Console.WriteLine(t.Result); Task<string> t2 = GetInfoAsync("TPL 2"); t2.ContinueWith(innerTask => Console.WriteLine(innerTask.Result), TaskContinuationOptions.NotOnFaulted | TaskContinuationOptions.AttachedToParent); t2.ContinueWith(innerTask => Console.WriteLine(innerTask.Exception.InnerException), TaskContinuationOptions.OnlyOnFaulted | TaskContinuationOptions.AttachedToParent); }, TaskContinuationOptions.NotOnFaulted | TaskContinuationOptions.AttachedToParent); t.ContinueWith(task => Console.WriteLine(t.Exception.InnerException), TaskContinuationOptions.OnlyOnFaulted | TaskContinuationOptions.AttachedToParent); }); containerTask.Start(); return containerTask; } static async Task AsynchronyWithAwait() { try { // 使用了两个await操作符，但代码还是按顺序执行的 string result = await GetInfoAsync("Async 1"); Console.WriteLine(result); result = await GetInfoAsync("Async 2"); Console.WriteLine(result); } catch (Exception ex) { Console.WriteLine(ex); } } static async Task<string> GetInfoAsync(string name) { Console.WriteLine($"Task {name} started!"); await Task.Delay(TimeSpan.FromSeconds(2)); if (name == "TPL 2" || name == "Async 2") { throw new Exception("Boom!"); } return $"Task {name} is running on a thrad id {Thread.CurrentThread.ManagedThreadId}. " + $"Is thread pool thread: {Thread.CurrentThread.IsThreadPoolThread}"; } ``` 打印结果 ``` Task TPL 1 started! Task TPL 1 is running on a thrad id 4. Is thread pool thread: True Task TPL 2 started! System.Exception: Boom! 在 Recipe5_3.Program.<GetInfoAsync>d__3.MoveNext() 位置 C:\Users\liujiajia\So urce\Repos\learn-multi-threading\Recipe5-3\Program.cs:行号 72 Task Async 1 started! Task Async 1 is running on a thrad id 3. Is thread pool thread: True Task Async 2 started! System.Exception: Boom! 在 Recipe5_3.Program.<GetInfoAsync>d__3.MoveNext() 位置 C:\Users\liujiajia\So urce\Repos\learn-multi-threading\Recipe5-3\Program.cs:行号 72 --- 引发异常的上一位置中堆栈跟踪的末尾 --- 在 System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task) 在 System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNot ification(Task task) 在 System.Runtime.CompilerServices.TaskAwaiter`1.GetResult() 在 Recipe5_3.Program.<AsynchronyWithAwait>d__2.MoveNext() 位置 C:\Users\liuji ajia\Source\Repos\learn-multi-threading\Recipe5-3\Program.cs:行号 57 ``` Loading... 版权声明：本文为博主「佳佳」的原创文章，遵循 CC 4.0 BY-NC-SA 版权协议，转载请附上原文出处链接及本声明。 原文链接：https://www.liujiajia.me/2017/7/28/csharp-multi-threading-05-csharp6-03-multi-await 提交
