TaskFactory<TResult> 类

定义

generic <typename TResult>
public ref class TaskFactory

public class TaskFactory<TResult>

type TaskFactory<'Result> = class

Public Class TaskFactory(Of TResult)

类型参数

继承

Object

TaskFactory<TResult>

示例

下面的示例使用静态 Factory 属性对方法进行两次调用 TaskFactory<TResult>.StartNew 。The following example uses the static Factory property to make two calls to the TaskFactory<TResult>.StartNew method. 第一项任务返回一个字符串数组，该字符串数组使用用户的 MyDocuments 目录中的文件的名称进行填充，第二个任务返回一个字符串数组，该数组使用用户的 MyDocuments 目录的子目录名称填充。The first task returns a string array that is populated with the names of files in the user's MyDocuments directory, while the second returns a string array that is populated with the names of subdirectories of the user's MyDocuments directory. 然后，它调用 TaskFactory.ContinueWhenAll(Task[], Action<Task[]>) 方法，该方法显示两个任务完成执行后返回的数组中的文件和目录的数量信息。It then calls the TaskFactory.ContinueWhenAll(Task[], Action<Task[]>) method, which displays information about the number of files and directories in the arrays returned by the two tasks after they have completed execution.

using System;
using System.IO;
using System.Threading.Tasks;

public class Example
{
   public static void Main()
   {
      Task<string[]>[] tasks = new Task<string[]>[2];
      String docsDirectory = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments);

      tasks[0] = Task<string[]>.Factory.StartNew( () => Directory.GetFiles(docsDirectory));
      tasks[1] = Task<string[]>.Factory.StartNew( () => Directory.GetDirectories(docsDirectory));

      Task.Factory.ContinueWhenAll(tasks, completedTasks => {
                                             Console.WriteLine("{0} contains: ", docsDirectory);
                                             Console.WriteLine("   {0} subdirectories", tasks[1].Result.Length);
                                             Console.WriteLine("   {0} files", tasks[0].Result.Length);
                                          } );
   }
}
// The example displays output like the following:
//       C:\Users\<username>\Documents contains:
//          24 subdirectories
//          16 files

Imports System.IO
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim tasks(1) As Task(Of String())
      Dim docsDirectory As String = Environment.GetFolderPath(Environment.SpecialFolder.MyDocuments)
      
      tasks(0) = Task(Of String()).Factory.StartNew( Function()Directory.GetFiles(docsDirectory) )
''                                        End Sub )
      tasks(1) = Task(Of String()).Factory.StartNew( Function() Directory.GetDirectories(docsDirectory) )
''                                        End Sub )
      Task.Factory.ContinueWhenAll(tasks, Sub(completedTasks)
                                             Console.WriteLine("{0} contains: ", docsDirectory)
                                             Console.WriteLine("   {0} subdirectories", tasks(1).Result.Length)
                                             Console.WriteLine("   {0} files", tasks(0).Result.Length)
                                          End Sub)
   End Sub
End Module
' The example displays output like the following:
'       C:\Users\<username>\Documents contains:
'          24 subdirectories
'          16 files

注解

.NET Framework 提供了两个用于创建和计划任务的工厂：The .NET Framework provides two factories for creating and scheduling tasks:

• TaskFactory类，该类创建 Task 和 Task<TResult> 对象。The TaskFactory class, which creates Task and Task<TResult> objects.

• TaskFactory<TResult>类，该类用于创建 Task<TResult> 对象。The TaskFactory<TResult> class, which creates Task<TResult> objects.

TaskFactory<TResult>类允许你执行以下操作：The TaskFactory<TResult> class allows you to do the following:

• 创建一个任务，并通过调用方法立即启动该任务 StartNew 。Create a task and start it immediately by calling the StartNew method. 可以调用此方法的重载来创建和执行需要非默认参数的任务。You can call the overloads of this method to create and execute a task that requires non-default arguments.

  警告

  从开始 .NET Framework 4.5.NET Framework 4.5 ， Task.Run 方法提供了使用默认配置值创建任务并立即启动该任务的最简单方法。Starting with the .NET Framework 4.5.NET Framework 4.5, the Task.Run method provides the easiest way to create a task with default configuration values and start it immediately.

• 创建一个任务，该任务在数组中的任一任务通过调用或方法完成后开始 ContinueWhenAny ContinueWhenAny 。Create a task that starts when any one of the tasks in an array has completed by calling the ContinueWhenAny or ContinueWhenAny method.

• 创建一个任务，该任务将在数组中的所有任务通过调用或方法完成后启动 ContinueWhenAll ContinueWhenAll 。Create a task that starts when all the tasks in an array have completed by calling the ContinueWhenAll or ContinueWhenAll method.

静态 Task<TResult>.Factory 属性返回默认 TaskFactory<TResult> 对象。The static Task<TResult>.Factory property returns a default TaskFactory<TResult> object. 还可以调用 TaskFactory<TResult> 类构造函数之一来配置 Task<TResult> TaskFactory<TResult> 类创建的对象。You can also call one of the TaskFactory<TResult> class constructors to configure the Task<TResult> objects that the TaskFactory<TResult> class creates. 下面的示例配置一个新的 TaskFactory<TResult> 对象，以创建具有指定的取消标记、任务创建选项、延续选项和自定义任务计划程序的任务。The following example configures a new TaskFactory<TResult> object to create tasks that have a specified cancellation token, task creation options, continuation options, and a customized task scheduler.

using System;
using System.Collections.Generic;
using System.Threading;
using System.Threading.Tasks;

public class Example
{
   static CancellationTokenSource cts = new CancellationTokenSource();

   static TaskFactory<int> factory = new TaskFactory<int>(
      cts.Token,
      TaskCreationOptions.PreferFairness,
      TaskContinuationOptions.ExecuteSynchronously,
      new CustomScheduler());

   static void Main()
   {
      var t2 = factory.StartNew(() => DoWork());
      cts.Dispose();
   }

   static int DoWork()
   {
       /*...*/
       return DateTime.Now.Hour <= 12 ?  1 : 2;
    }
}

Imports System.Collections.Generic
Imports System.Threading
Imports System.Threading.Tasks

Module Example
   Public Sub Main()
      Dim cts As New CancellationTokenSource()
      Dim factory As New TaskFactory(Of Integer)(
                         cts.Token,
                         TaskCreationOptions.PreferFairness,
                         TaskContinuationOptions.ExecuteSynchronously,
                         New CustomScheduler())

      Dim t2 = factory.StartNew(Function() DoWork())
      cts.Dispose()
   End Sub

   Function DoWork() As Integer
      Return If(Date.Now.Hour <= 12, 1, 2)
   End Function
End Module

在大多数情况下，您不必实例化新的 TaskFactory<TResult> 实例。In most cases, you do not have to instantiate a new TaskFactory<TResult> instance. 相反，可以使用 static Task<TResult>.Factory 属性，该属性返回使用默认值的工厂对象。Instead, you can use the static Task<TResult>.Factory property, which returns a factory object that uses default values. 然后，可以调用其方法来启动新任务或定义任务延续。You can then call its methods to start new tasks or define task continuations. 有关说明，请参阅示例。For an illustration, see the example.

构造函数

属性

方法

适用于

线程安全性

的所有公共和受保护的成员 TaskFactory<TResult> 都是线程安全的，可从多个线程并发使用。All public and protected members of TaskFactory<TResult> are thread-safe and may be used concurrently from multiple threads.

另请参阅

• 任务并行库 (TPL)Task Parallel Library (TPL)