IAsyncResult 接口
表示异步操作的状态。
**命名空间:**System
**程序集:**mscorlib（在 mscorlib.dll 中）
语法
声明
<ComVisibleAttribute(True)> _
Public Interface IAsyncResult
用法
Dim instance As IAsyncResult
[ComVisibleAttribute(true)]
public interface IAsyncResult
[ComVisibleAttribute(true)]
public interface class IAsyncResult
/** @attribute ComVisibleAttribute(true) */
public interface IAsyncResult
ComVisibleAttribute(true)
public interface IAsyncResult
备注
IAsyncResult 接口由包含可异步操作的方法的类实现。它是启动异步操作的方法的返回类型，如 FileStream.BeginRead，也是结束异步操作的方法的第三个参数的类型，如 FileStream.EndRead。当异步操作完成时，IAsyncResult 对象也将传递给由 AsyncCallback 委托调用的方法。
支持 IAsyncResult 接口的对象存储异步操作的状态信息，并提供同步对象以允许线程在操作完成时终止。
有关如何使用 IAsyncResult 接口的详细说明，请参见“使用异步方式调用同步方法”主题。
示例
下面的示例说明如何使用 IAsyncResult 来获取异步操作的返回值。
' Asynchronous Callback method.
Public Shared Sub MyCallback(ar As IAsyncResult)
' Obtains the last parameter of the delegate call.
Dim value As Integer = Convert.ToInt32(ar.AsyncState)
' Obtains return value from the delegate call using EndInvoke.
Dim aResult As AsyncResult = CType(ar, AsyncResult)
Dim temp As SampSyncSqrDelegate = CType(aResult.AsyncDelegate, SampSyncSqrDelegate)
Dim result As Integer = temp.EndInvoke(ar)
Console.Write("Simple.SomeMethod (AsyncCallback): Result of ")
Console.WriteLine("{0} in SampleSynchronized.Square is {1} ", value, result)
End Sub 'MyCallback
// Asynchronous Callback method.
public static void MyCallback(IAsyncResult ar) {
// Obtains the last parameter of the delegate call.
int value = Convert.ToInt32(ar.AsyncState);
// Obtains return value from the delegate call using EndInvoke.
AsyncResult aResult = (AsyncResult)ar;
SampSyncSqrDelegate temp = (SampSyncSqrDelegate)aResult.AsyncDelegate;
int result = temp.EndInvoke(ar);
Console.Write("Simple.SomeMethod (AsyncCallback): Result of ");
Console.WriteLine("{0} in SampleSynchronized.Square is {1} ", value, result);
}
// Asynchronous Callback method.
static void MyCallback( IAsyncResult^ ar )
{
// Obtains the last parameter of the delegate call.
int value = Convert::ToInt32( ar->AsyncState );
// Obtains return value from the delegate call using EndInvoke.
AsyncResult^ aResult = dynamic_cast<AsyncResult^>(ar);
SampSyncSqrDelegate^ temp = static_cast<SampSyncSqrDelegate^>(aResult->AsyncDelegate);
int result = temp->EndInvoke( ar );
Console::Write( "Simple::SomeMethod (AsyncCallback): Result of " );
Console::WriteLine( " {0} in SampleSynchronized::Square is {1} ", value, result );
}
// Asynchronous Callback method.
public static void MyCallback(IAsyncResult ar)
{
// Obtains the last parameter of the delegate call.
SampSyncSqrDelegate sampDelg = (SampSyncSqrDelegate)ar.get_AsyncState();
// Obtains return value from the delegate call using EndInvoke.
AsyncResult aResult = (AsyncResult)ar;
SampSyncSqrDelegate temp =
(SampSyncSqrDelegate)(aResult.get_AsyncDelegate());
int threadId = AppDomain.GetCurrentThreadId();
int result = temp.EndInvoke(ar);
Console.Write("Simple.SomeMethod (AsyncCallback): Result of ");
Console.WriteLine("{0} in SampleSynchronized.Square is {1} ",
(Int32)value, (Int32)result);
} //MyCallback
下面的示例演示等待异步操作完成。
Imports System
Imports System.Threading
Imports System.Runtime.Remoting
Imports System.Runtime.Remoting.Contexts
Imports System.Runtime.Remoting.Messaging
'
' Context-Bound type with Synchronization Context Attribute
'
<Synchronization()> Public Class SampleSyncronized
Inherits ContextBoundObject
' A method that does some work - returns the square of the given number
Public Function Square(i As Integer) As Integer
Console.Write("SampleSyncronized.Square called. ")
Console.WriteLine("The hash of the current thread is: {0}", Thread.CurrentThread.GetHashCode())
Return i * i
End Function 'Square
End Class 'SampleSyncronized
'
' Async delegate used to call a method with this signature asynchronously
'
Delegate Function SampSyncSqrDelegate(i As Integer) As Integer
'Main sample class
Public Class AsyncResultSample
Public Shared Sub Main()
Dim callParameter As Integer = 0
Dim callResult As Integer = 0
'Create an instance of a context-bound type SampleSynchronized
'Because SampleSynchronized is context-bound, the object sampSyncObj
'is a transparent proxy
Dim sampSyncObj As New SampleSyncronized()
'call the method synchronously
Console.Write("Making a synchronous call on the object. ")
Console.WriteLine("The hash of the current thread is: {0}", Thread.CurrentThread.GetHashCode())
callParameter = 10
callResult = sampSyncObj.Square(callParameter)
Console.WriteLine("Result of calling sampSyncObj.Square with {0} is {1}.", callParameter, callResult)
Console.WriteLine("")
Console.WriteLine("")
'call the method asynchronously
Console.Write("Making an asynchronous call on the object. ")
Console.WriteLine("The hash of the current thread is: {0}", Thread.CurrentThread.GetHashCode())
Dim sampleDelegate As New SampSyncSqrDelegate(AddressOf sampSyncObj.Square)
callParameter = 17
Dim aResult As IAsyncResult = sampleDelegate.BeginInvoke(callParameter, Nothing, Nothing)
'Wait for the call to complete
aResult.AsyncWaitHandle.WaitOne()
callResult = sampleDelegate.EndInvoke(aResult)
Console.WriteLine("Result of calling sampSyncObj.Square with {0} is {1}.", callParameter, callResult)
End Sub 'Main
End Class 'AsyncResultSample
using System;
using System.Threading;
using System.Runtime.Remoting;
using System.Runtime.Remoting.Contexts;
using System.Runtime.Remoting.Messaging;
//
// Context-Bound type with Synchronization Context Attribute
//
[Synchronization()]
public class SampleSyncronized : ContextBoundObject
{
// A method that does some work - returns the square of the given number
public int Square(int i)
{
Console.Write("SampleSyncronized.Square called. ");
Console.WriteLine("The hash of the current thread is: {0}", Thread.CurrentThread.GetHashCode());
return i*i;
}
}
//
// Async delegate used to call a method with this signature asynchronously
//
public delegate int SampSyncSqrDelegate(int i);
//Main sample class
public class AsyncResultSample
{
public static void Main()
{
int callParameter = 0;
int callResult = 0;
//Create an instance of a context-bound type SampleSynchronized
//Because SampleSynchronized is context-bound, the object sampSyncObj
//is a transparent proxy
SampleSyncronized sampSyncObj = new SampleSyncronized();
//call the method synchronously
Console.Write("Making a synchronous call on the object. ");
Console.WriteLine("The hash of the current thread is: {0}", Thread.CurrentThread.GetHashCode());
callParameter = 10;
callResult = sampSyncObj.Square(callParameter);
Console.WriteLine("Result of calling sampSyncObj.Square with {0} is {1}.\n\n", callParameter, callResult);
//call the method asynchronously
Console.Write("Making an asynchronous call on the object. ");
Console.WriteLine("The hash of the current thread is: {0}", Thread.CurrentThread.GetHashCode());
SampSyncSqrDelegate sampleDelegate = new SampSyncSqrDelegate(sampSyncObj.Square);
callParameter = 17;
IAsyncResult aResult = sampleDelegate.BeginInvoke(callParameter, null, null);
//Wait for the call to complete
aResult.AsyncWaitHandle.WaitOne();
callResult = sampleDelegate.EndInvoke(aResult);
Console.WriteLine("Result of calling sampSyncObj.Square with {0} is {1}.", callParameter, callResult);
}
}
using namespace System;
using namespace System::Threading;
using namespace System::Runtime::Remoting;
using namespace System::Runtime::Remoting::Contexts;
using namespace System::Runtime::Remoting::Messaging;
//
// Context-Bound type with Synchronization Context Attribute
//
public ref class SampleSyncronized: public ContextBoundObject
{
public:
// A method that does some work - returns the square of the given number
int Square( int i )
{
Console::Write( "SampleSyncronized::Square called. " );
Console::WriteLine( "The hash of the current thread is: {0}", Thread::CurrentThread->GetHashCode() );
return i * i;
}
};
delegate int SampSyncSqrDelegate( //
// Async delegate used to call a method with this signature asynchronously
//
int i );
//Main sample class
int main()
{
int callParameter = 0;
int callResult = 0;
//Create an instance of a context-bound type SampleSynchronized
//Because SampleSynchronized is context-bound, the Object* sampSyncObj
//is a transparent proxy
SampleSyncronized^ sampSyncObj = gcnew SampleSyncronized;
//call the method synchronously
Console::Write( "Making a synchronous call on the Object*. " );
Console::WriteLine( "The hash of the current thread is: {0}", Thread::CurrentThread->GetHashCode() );
callParameter = 10;
callResult = sampSyncObj->Square( callParameter );
Console::WriteLine( "Result of calling sampSyncObj.Square with {0} is {1}.\n\n", callParameter, callResult );
//call the method asynchronously
Console::Write( "Making an asynchronous call on the Object*. " );
Console::WriteLine( "The hash of the current thread is: {0}", Thread::CurrentThread->GetHashCode() );
SampSyncSqrDelegate^ sampleDelegate = gcnew SampSyncSqrDelegate( sampSyncObj, &SampleSyncronized::Square );
callParameter = 17;
IAsyncResult^ aResult = sampleDelegate->BeginInvoke( callParameter, nullptr, 0 );
//Wait for the call to complete
aResult->AsyncWaitHandle->WaitOne();
callResult = sampleDelegate->EndInvoke( aResult );
Console::WriteLine( "Result of calling sampSyncObj.Square with {0} is {1}.", callParameter, callResult );
}
平台
Windows 98、Windows 2000 SP4、Windows CE、Windows Millennium Edition、Windows Mobile for Pocket PC、Windows Mobile for Smartphone、Windows Server 2003、Windows XP Media Center Edition、Windows XP Professional x64 Edition、Windows XP SP2、Windows XP Starter Edition
.NET Framework 并不是对每个平台的所有版本都提供支持。有关受支持版本的列表，请参见系统要求。
版本信息
.NET Framework
受以下版本支持：2.0、1.1、1.0
.NET Compact Framework
受以下版本支持：2.0、1.0