Task<TResult>.Factory 屬性

定義

提供 Factory 方法的存取,這些 Factory 方法用於建立及設定 Task<TResult> 執行個體。Provides access to factory methods for creating and configuring Task<TResult> instances.

public:
 static property System::Threading::Tasks::TaskFactory<TResult> ^ Factory { System::Threading::Tasks::TaskFactory<TResult> ^ get(); };
public static System.Threading.Tasks.TaskFactory<TResult> Factory { get; }
member this.Factory : System.Threading.Tasks.TaskFactory<'Result>
Public Shared ReadOnly Property Factory As TaskFactory(Of TResult)

屬性值

Factory 物件,可以建立各種不同的 Task<TResult> 物件。A factory object that can create a variety of Task<TResult> objects.

備註

這個屬性會傳回TaskFactory<TResult>類別的預設實例, 與呼叫無參數TaskFactory<TResult>.TaskFactory<TResult>()的函式所建立的相同。This property returns a default instance of the TaskFactory<TResult> class that is identical to the one created by calling the parameterless TaskFactory<TResult>.TaskFactory<TResult>() constructor. 它具有下列屬性值:It has the following property values:

屬性Property Value
TaskFactory<TResult>.CancellationToken CancellationToken.None
TaskFactory<TResult>.ContinuationOptions TaskContinuationOptions.None
TaskFactory<TResult>.CreationOptions TaskCreationOptions.None
TaskFactory<TResult>.Scheduler null、或TaskScheduler.Currentnull, or TaskScheduler.Current

此屬性最常見的用法是在TaskFactory<TResult>.StartNew方法的單一呼叫中建立並啟動新的工作。The most common use of this property is to create and start a new task in a single call to the TaskFactory<TResult>.StartNew method.

注意

從開始.NET Framework 4.5.NET Framework 4.5 Task<TResult> , 方法會提供最簡單的方式來建立具有預設設定值的物件。 Task.RunStarting with the .NET Framework 4.5.NET Framework 4.5, the Task.Run method provides the easiest way to create a Task<TResult> object with default configuration values.

下列範例會使用靜態Factory屬性來對TaskFactory<TResult>.StartNew方法進行三個呼叫。The following example uses the static Factory property to make three calls to the TaskFactory<TResult>.StartNew method. 第一個會啟動Task<Int32>一個物件, 它會執行傳回1的 lambda 運算式。The first starts a Task<Int32> object, which executes a lambda expression that returns 1. 第二個啟動Task<Test>物件, 它會執行具現化新Test實例的 lambda 運算式。The second starts a Task<Test> object, which executes a lambda expression that instantiates a new Test instance. 第三個會Task<String[]>啟始物件, 它會列舉 C:\Users\Public\Pictures\Sample Pictures \ 目錄中的檔案。The third starts a Task<String[]> object, which enumerates the files in the C:\Users\Public\Pictures\Sample Pictures\ directory. (請注意, 成功執行此範例需要目錄存在, 而且它包含檔案。(Note that successful execution of the example requires that the directory exist and that it contain files.

using System;
using System.Linq;
using System.Threading.Tasks;

class Program
{
    static void Main()
    {
        // Return a value type with a lambda expression
        Task<int> task1 = Task<int>.Factory.StartNew(() => 1);
        int i = task1.Result;

        // Return a named reference type with a multi-line statement lambda.
        Task<Test> task2 = Task<Test>.Factory.StartNew(() =>
        {
            string s = ".NET";
            double d = 4.0;
            return new Test { Name = s, Number = d };
        });
        Test test = task2.Result;

        // Return an array produced by a PLINQ query
        Task<string[]> task3 = Task<string[]>.Factory.StartNew(() =>
        {
            string path = @"C:\Users\Public\Pictures\Sample Pictures\";
            string[] files = System.IO.Directory.GetFiles(path);

            var result = (from file in files.AsParallel()
                          let info = new System.IO.FileInfo(file)
                          where info.Extension == ".jpg"
                          select file).ToArray();

            return result;
        });

        foreach (var name in task3.Result)
            Console.WriteLine(name);

    }
    class Test
    {
        public string Name { get; set; }
        public double Number { get; set; }

    }
}
Imports System.Threading.Tasks

Module Module1

    Sub Main()
        ReturnAValue()

        Console.WriteLine("Press any key to exit.")
        Console.ReadKey()

    End Sub

    Sub ReturnAValue()

        ' Return a value type with a lambda expression
        Dim task1 = Task(Of Integer).Factory.StartNew(Function() 1)
        Dim i As Integer = task1.Result

        ' Return a named reference type with a multi-line statement lambda.
        Dim task2 As Task(Of Test) = Task.Factory.StartNew(Function()
                                                               Dim s As String = ".NET"
                                                               Dim d As Integer = 4
                                                               Return New Test With {.Name = s, .Number = d}
                                                           End Function)

        Dim myTest As Test = task2.Result
        Console.WriteLine(myTest.Name & ": " & myTest.Number)

        ' Return an array produced by a PLINQ query.
        Dim task3 As Task(Of String())= Task(Of String()).Factory.StartNew(Function()

                                                           Dim path = "C:\Users\Public\Pictures\Sample Pictures\"
                                                           Dim files = System.IO.Directory.GetFiles(path)

                                                           Dim result = (From file In files.AsParallel()
                                                                Let info = New System.IO.FileInfo(file)
                                                                Where info.Extension = ".jpg"
                                                                Select file).ToArray()
                                                           Return result
                                                       End Function)

        For Each name As String In task3.Result
            Console.WriteLine(name)
        Next
    End Sub

    Class Test
        Public Name As String
        Public Number As Double
    End Class
End Module

適用於

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