Thread.TrySetApartmentState(ApartmentState) 方法

定义

命名空间:

System.Threading

程序集:

System.Threading.Thread.dll

程序集:

netstandard.dll

程序集:

mscorlib.dll

在线程启动前设置其单元状态。

public:
 bool TrySetApartmentState(System::Threading::ApartmentState state);

public bool TrySetApartmentState (System.Threading.ApartmentState state);

member this.TrySetApartmentState : System.Threading.ApartmentState -> bool

Public Function TrySetApartmentState (state As ApartmentState) As Boolean

参数

state

ApartmentState

新的单元状态。

返回

Boolean

如果设置了单元状态，则为 true；否则为 false。

例外

PlatformNotSupportedException

仅适用于 .NET Core 和 .NET 5 +：在 macOS 和 Linux 的所有情况下。

ArgumentException

state 不是有效的单元状态。

ThreadStateException

线程曾启动但已终止，或未在线程运行时从线程的上下文中进行调用。

示例

下面的代码示例演示了 GetApartmentState 、 SetApartmentState 和 TrySetApartmentState 方法。 此代码示例创建一个线程。 启动线程之前，会 GetApartmentState 显示初始状态， ApartmentState.Unknown 并将 SetApartmentState 状态更改为 ApartmentState.STA 。 TrySetApartmentState false 如果 ApartmentState.MTA 已设置了单元状态，则在尝试将状态更改为时，该方法将返回。 如果尝试了同一操作 SetApartmentState ，则 InvalidOperationException 会引发。

线程启动后，将 TrySetApartmentState 再次使用该方法。 这是 ThreadStateException 因为线程已启动。

using namespace System;
using namespace System::Threading;

void ThreadProc()
{
    Thread::Sleep(2000);
};

void main()
{
    Thread^ t = gcnew Thread(gcnew ThreadStart(ThreadProc));
    Console::WriteLine("Before setting apartment state: {0}", 
            t->GetApartmentState());

    t->SetApartmentState(ApartmentState::STA);
    Console::WriteLine("After setting apartment state: {0}", 
        t->GetApartmentState());

    bool result = t->TrySetApartmentState(ApartmentState::MTA);
    Console::WriteLine("Try to change state: {0}", result);

    t->Start();

    Thread::Sleep(500);

    try
    {
        t->TrySetApartmentState(ApartmentState::STA);
    }
    catch (ThreadStateException^)
    {
        Console::WriteLine("ThreadStateException occurs " +
            "if apartment state is set after starting thread.");
    }

    t->Join();
}

/* This code example produces the following output:

Before setting apartment state: Unknown
After setting apartment state: STA
Try to change state: False
ThreadStateException occurs if apartment state is set after starting thread.
 */

using System;
using System.Threading;

class Example
{
    public static void Main()
    {
        Thread t = new Thread(ThreadProc);
        Console.WriteLine("Before setting apartment state: {0}",
            t.GetApartmentState());

        t.SetApartmentState(ApartmentState.STA);
        Console.WriteLine("After setting apartment state: {0}",
            t.GetApartmentState());

        bool result = t.TrySetApartmentState(ApartmentState.MTA);
        Console.WriteLine("Try to change state: {0}", result);

        t.Start();

        Thread.Sleep(500);

        try
        {
            t.TrySetApartmentState(ApartmentState.STA);
        }
        catch (ThreadStateException)
        {
            Console.WriteLine("ThreadStateException occurs " +
                "if apartment state is set after starting thread.");
        }

        t.Join();
    }

    public static void ThreadProc()
    {
        Thread.Sleep(2000);
    }
}

/* This code example produces the following output:

Before setting apartment state: Unknown
After setting apartment state: STA
Try to change state: False
ThreadStateException occurs if apartment state is set after starting thread.
 */

Imports System.Threading

Module Example

    Sub Main()
 
        Dim t As New Thread(AddressOf ThreadProc)
        Console.WriteLine("Before setting apartment state: {0}", _
            t.GetApartmentState())

        t.SetApartmentState(ApartmentState.STA)
        Console.WriteLine("After setting apartment state: {0}", _
            t.GetApartmentState())

        Dim result As Boolean = _
            t.TrySetApartmentState(ApartmentState.MTA)
        Console.WriteLine("Try to change state: {0}", result)

        t.Start()

        Thread.Sleep(500)

        Try
            t.TrySetApartmentState(ApartmentState.STA)
        Catch ex As ThreadStateException
            Console.WriteLine("ThreadStateException occurs " & _
                "if apartment state is set after starting thread.")
        End Try

        t.Join()
    End Sub

    Sub ThreadProc()
        Thread.Sleep(2000)
    End Sub
End Module

' This code example produces the following output:
'
'Before setting apartment state: Unknown
'After setting apartment state: STA
'Try to change state: False
'ThreadStateException occurs if apartment state is set after starting thread.

注解

新线程将初始化，就好像它们 ApartmentState.MTA 的单元状态在启动之前尚未设置。 必须在启动线程之前设置单元状态。

备注

默认情况下，主应用程序线程将初始化为 ApartmentState.MTA 。 将主应用程序线程的单元状态设置为的唯一方法 ApartmentState.STA 是将属性应用于 STAThreadAttribute 入口点方法。

TrySetApartmentState方法连同 GetApartmentState 方法和 SetApartmentState 方法替换 ApartmentState 属性。