FileStream.IsAsync FileStream.IsAsync FileStream.IsAsync FileStream.IsAsync Property

Definición

Obtiene un valor que indica si se ha abierto FileStream de forma sincrónica o asincrónica.Gets a value that indicates whether the FileStream was opened asynchronously or synchronously.

public:
 virtual property bool IsAsync { bool get(); };
public virtual bool IsAsync { get; }
member this.IsAsync : bool
Public Overridable ReadOnly Property IsAsync As Boolean

Valor de propiedad

Es true si FileStream se abrió de forma asincrónica; de lo contrario, es false.true if the FileStream was opened asynchronously; otherwise, false.

Ejemplos

Este ejemplo de código forma parte de un ejemplo mayor proporcionado para FileStream(String, FileMode, FileAccess, FileShare, Int32, Boolean) el constructor.This code example is part of a larger example provided for the FileStream(String, FileMode, FileAccess, FileShare, Int32, Boolean) constructor.

int main()
{
   
   // Create a synchronization object that gets 
   // signaled when verification is complete.
   ManualResetEvent^ manualEvent = gcnew ManualResetEvent( false );
   
   // Create the data to write to the file.
   array<Byte>^writeArray = gcnew array<Byte>(100000);
   (gcnew Random)->NextBytes( writeArray );
   FileStream^ fStream = gcnew FileStream(  "Test#@@#.dat",FileMode::Create,FileAccess::ReadWrite,FileShare::None,4096,true );
   
   // Check that the FileStream was opened asynchronously.
   Console::WriteLine( "fStream was {0}opened asynchronously.", fStream->IsAsync ? (String^)"" : "not " );
   
   // Asynchronously write to the file.
   IAsyncResult^ asyncResult = fStream->BeginWrite( writeArray, 0, writeArray->Length, gcnew AsyncCallback( &FStream::EndWriteCallback ), gcnew State( fStream,writeArray,manualEvent ) );
   
   // Concurrently do other work and then wait 
   // for the data to be written and verified.
   manualEvent->WaitOne( 5000, false );
}

static void Main()
{
    // Create a synchronization object that gets 
    // signaled when verification is complete.
    ManualResetEvent manualEvent = new ManualResetEvent(false);

    // Create random data to write to the file.
    byte[] writeArray = new byte[100000];
    new Random().NextBytes(writeArray);

    FileStream fStream = 
        new FileStream("Test#@@#.dat", FileMode.Create, 
        FileAccess.ReadWrite, FileShare.None, 4096, true);

    // Check that the FileStream was opened asynchronously.
    Console.WriteLine("fStream was {0}opened asynchronously.",
        fStream.IsAsync ? "" : "not ");

    // Asynchronously write to the file.
    IAsyncResult asyncResult = fStream.BeginWrite(
        writeArray, 0, writeArray.Length, 
        new AsyncCallback(EndWriteCallback), 
        new State(fStream, writeArray, manualEvent));

    // Concurrently do other work and then wait 
    // for the data to be written and verified.
    manualEvent.WaitOne(5000, false);
}
Shared Sub Main()

    ' Create a synchronization object that gets 
    ' signaled when verification is complete.
    Dim manualEvent As New ManualResetEvent(False)

    ' Create random data to write to the file.
    Dim writeArray(100000) As Byte
    Dim randomGenerator As New Random()
    randomGenerator.NextBytes(writeArray)

    Dim fStream As New FileStream("Test#@@#.dat", _
        FileMode.Create, FileAccess.ReadWrite, _
        FileShare.None, 4096, True)

    ' Check that the FileStream was opened asynchronously.
    If fStream.IsAsync = True
        Console.WriteLine("fStream was opened asynchronously.")
    Else
        Console.WriteLine("fStream was not opened asynchronously.")
    End If

    ' Asynchronously write to the file.
    Dim asyncResult As IAsyncResult = fStream.BeginWrite( _
        writeArray, 0, writeArray.Length, _
        AddressOf EndWriteCallback , _
        New State(fStream, writeArray, manualEvent))

    ' Concurrently do other work and then wait
    ' for the data to be written and verified.
    manualEvent.WaitOne(5000, False)
End Sub

Comentarios

La IsAsync propiedad detecta si se abrió FileStream el identificador de forma asincrónica, lo que permite que el Handle código use la propiedad correctamente.The IsAsync property detects whether the FileStream handle was opened asynchronously, enabling your code to use the Handle property correctly. En Win32, IsAsync es true significa que el identificador se abrió para e/s superpuestas y, por tanto, ReadFile requiere WriteFileparámetros diferentes para y.In Win32, IsAsync being true means the handle was opened for overlapped I/O, and thus requires different parameters to ReadFile and WriteFile.

Este valor se especifica cuando se crea una instancia de la FileStream clase mediante un constructor que tiene un isAsyncparámetro useAsync, o options .You specify this value when you create an instance of the FileStream class using a constructor that has an isAsync, useAsync, or options parameter. Cuando la propiedad es true, la secuencia emplea la e/s superpuesta para realizar operaciones de archivo de forma asincrónica.When the property is true, the stream utilizes overlapped I/O to perform file operations asynchronously. Sin embargo, IsAsync la propiedad no tiene que ser true llamar ReadAsyncal método, WriteAsynco CopyToAsync .However, the IsAsync property does not have to be true to call the ReadAsync, WriteAsync, or CopyToAsync method. Cuando la IsAsync propiedad es false y se llama a las operaciones asincrónicas de lectura y escritura, el subproceso de la interfaz de usuario sigue sin estar bloqueado, pero la operación de e/s real se realiza sincrónicamente.When the IsAsync property is false and you call the asynchronous read and write operations, the UI thread is still not blocked, but the actual I/O operation is performed synchronously.

Se aplica a

Consulte también: