异步Task的创建方式
農碼一生 人气:0一、简介
ThreadPool相比Thread来说具备了很多优势,但是ThreadPool却又存在一些使用上的不方便。比如:
Task支持线程的取消、完成、失败通知等交互性操作,但是ThreadPool不支持;
Task支持线程执行的先后次序,但是ThreadPool不支持;;
以往,如果开发者要实现上述功能,需要完成很多额外的工作,现在,FCL中提供了一个功能更强大的概念:Task。Task在线程池的基础上进行了优化,并提供了更多的API。在FCL4.0中,如果我们要编写多线程程序,Task显然已经优于传统的方式。
Task t = new Task(() => { Console.WriteLine("Start……"); //模拟工作过程 Thread.Sleep(5000); }); t.Start(); t.ContinueWith((task) => { Console.WriteLine("Already Finished,States:"); Console.WriteLine("IsCanceled={0}\tIsCompleted={1}\tIsFaulted={2}", task.IsCanceled, task.IsCompleted, task.IsFaulted); }); Console.ReadKey();
二、Task创建
无返回值创建方式
线程引用方法:
static void TaskMethod(string name) { Console.WriteLine("Task: {0} is running on a thread id {1}. Is thread pool thread: {2}", name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread); }
方式一:
//方式一 var t1 = new Task(() => TaskMethod("Task_1")); t1.Start(); //等待所有任务结束 //任务的状态: //Start之前为:Created //Start之后为:WaitingToRun Task.WaitAll(t1);////等待所有任务结束
方式二:
//方式二 Task.Run(() => TaskMethod("Task_2"));
方式三:
//方式三 Task.Factory.StartNew(() => TaskMethod("Task_3")); //直接异步的方法 //或者 var t3 = Task.Factory.StartNew(() => TaskMethod("Task_3")); Task.WaitAll(t3);//等待所有任务结束 //任务的状态 //Start之前为:Running //Start之后为:Running
实例:
class Program { static void Main(string[] args) { var t1 = new Task(() => TaskMethod("Task_1")); var t2 = new Task(() => TaskMethod("Task_2")); t2.Start(); t1.Start(); Task.WaitAll(t1, t2); Task.Run(() => TaskMethod("Task_3")); Task.Factory.StartNew(() => TaskMethod("Task_4")); //标记为长时间运行任务,则任务不会使用线程池,而在单独的线程中运行。 Task.Factory.StartNew(() => TaskMethod("Task_5"), TaskCreationOptions.LongRunning); #region 常规的使用方式 Console.WriteLine("主線程執行業務處理."); //创建任务 Task task = new Task(() => { Console.WriteLine("使用System.Threading.Tasks.Task執行異步操作."); for (int i = 0; i < 10; i++) { Console.WriteLine(i); } }); //启动任务,并安排到当前任务队列线程中执行任务(System.Threading.Tasks.TaskScheduler) task.Start(); Console.WriteLine("主線程執行其他處理"); task.Wait(); #endregion Thread.Sleep(TimeSpan.FromSeconds(1)); Console.ReadLine(); } static void TaskMethod(string name) { Console.WriteLine("Task {0} is running on a thread id {1}. Is thread pool thread: {2}", name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread); } }
结果:
async/await的实现方式:
class Program { async static void AsyncFunction() { await Task.Delay(1); Console.WriteLine("使用System.Threading.Tasks.Task執行異步操作."); for (int i = 0; i < 10; i++) { Console.WriteLine(string.Format("AsyncFunction:i={0}", i)); } } public static void Main() { Console.WriteLine("主線程執行業務處理."); AsyncFunction(); Console.WriteLine("主線程執行其他處理"); for (int i = 0; i < 10; i++) { Console.WriteLine(string.Format("Main:i={0}", i)); } Console.ReadLine(); } }
结果:
带返回值方式
线程引用方法
static Task<int> CreateTask(string name) { return new Task<int>(() => TaskMethod1(name)); }
static int TaskMethod1(string name) { Console.WriteLine("Task {0} is running on a thread id {1}. Is thread pool thread: {2}", name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread); Thread.Sleep(TimeSpan.FromSeconds(2)); return 42; }
方式四:
//方式四 Task<int> task = CreateTask("Task_1"); task.Start(); int result = task.Result;
实例:
class Program { static Task<int> CreateTask(string name) { return new Task<int>(() => TaskMethod(name)); } static void Main(string[] args) { TaskMethod("Main Thread Task"); Task<int> task = CreateTask("Task_1"); task.Start(); int result = task.Result; Console.WriteLine("Task_1 Result is: {0}", result); task = CreateTask("Task_2"); //该任务会运行在主线程中 task.RunSynchronously(); result = task.Result; Console.WriteLine("Task_2 Result is: {0}", result); task = CreateTask("Task_3"); Console.WriteLine(task.Status); task.Start(); while (!task.IsCompleted) { Console.WriteLine(task.Status); Thread.Sleep(TimeSpan.FromSeconds(0.5)); } Console.WriteLine(task.Status); result = task.Result; Console.WriteLine("Task_3 Result is: {0}", result); #region 常规使用方式 //创建任务 Task<int> getsumtask = new Task<int>(() => Getsum()); //启动任务,并安排到当前任务队列线程中执行任务(System.Threading.Tasks.TaskScheduler) getsumtask.Start(); Console.WriteLine("主線程執行其他處理"); //等待任务的完成执行过程。 getsumtask.Wait(); //获得任务的执行结果 Console.WriteLine("任務執行結果:{0}", getsumtask.Result.ToString()); Console.ReadLine(); #endregion } static int TaskMethod(string name) { Console.WriteLine("Task: {0} is running on a thread id {1}. Is thread pool thread: {2}", name, Thread.CurrentThread.ManagedThreadId, Thread.CurrentThread.IsThreadPoolThread); Thread.Sleep(TimeSpan.FromSeconds(2)); return 42; } static int Getsum() { int sum = 0; Console.WriteLine("使用Task執行異步操作."); for (int i = 0; i < 100; i++) { sum += i; } return sum; } }
结果:
async/await的实现:
class Program { public static void Main() { var ret1 = AsyncGetsum(); Console.WriteLine("主線程執行其他處理"); for (int i = 1; i <= 3; i++) Console.WriteLine("Call Main()"); int result = ret1.Result; //阻塞主线程 Console.WriteLine("任務執行結果:{0}", result); Console.ReadLine(); } async static Task<int> AsyncGetsum() { await Task.Delay(1); int sum = 0; Console.WriteLine("使用Task執行異步操作."); for (int i = 0; i < 100; i++) { sum += i; } return sum; } }
结果:
到此这篇关于C#创建异步Task的文章就介绍到这了。希望对大家的学习有所帮助,也希望大家多多支持。
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