Επεξεργασία

Κοινή χρήση μέσω

FileStream.EndWrite(IAsyncResult) Method

  • Reference

Definition

Namespace:
System.IO
Assembly:
System.Runtime.dll
Assembly:
mscorlib.dll
Assembly:
netstandard.dll
Source:
FileStream.cs
Source:
FileStream.cs
Source:
FileStream.cs

Ends an asynchronous write operation and blocks until the I/O operation is complete. (Consider using WriteAsync(Byte[], Int32, Int32, CancellationToken) instead.)

public:
 override void EndWrite(IAsyncResult ^ asyncResult);
public override void EndWrite (IAsyncResult asyncResult);
override this.EndWrite : IAsyncResult -> unit
Public Overrides Sub EndWrite (asyncResult As IAsyncResult)

Parameters

asyncResult
IAsyncResult

The pending asynchronous I/O request.

Exceptions

ArgumentNullException

asyncResult is null.

ArgumentException

This IAsyncResult object was not created by calling BeginWrite(Byte[], Int32, Int32, AsyncCallback, Object) on this class.

InvalidOperationException

EndWrite(IAsyncResult) is called multiple times.

IOException

The stream is closed or an internal error has occurred.

Examples

This code example is part of a larger example provided for the FileStream(String, FileMode, FileAccess, FileShare, Int32, Boolean) constructor.

   static void EndWriteCallback( IAsyncResult^ asyncResult )
   {
      State^ tempState = dynamic_cast<State^>(asyncResult->AsyncState);
      FileStream^ fStream = tempState->FStream;
      fStream->EndWrite( asyncResult );
      
      // Asynchronously read back the written data.
      fStream->Position = 0;
      asyncResult = fStream->BeginRead( tempState->ReadArray, 0, tempState->ReadArray->Length, gcnew AsyncCallback( &FStream::EndReadCallback ), tempState );
      
      // Concurrently do other work, such as 
      // logging the write operation.
   }

};

static void EndWriteCallback(IAsyncResult asyncResult)
{
    State tempState = (State)asyncResult.AsyncState;
    FileStream fStream = tempState.FStream;
    fStream.EndWrite(asyncResult);

    // Asynchronously read back the written data.
    fStream.Position = 0;
    asyncResult = fStream.BeginRead(
        tempState.ReadArray, 0 , tempState.ReadArray.Length,
        new AsyncCallback(EndReadCallback), tempState);

    // Concurrently do other work, such as
    // logging the write operation.
}

let endWriteCallback (asyncResult: IAsyncResult) =
    let tempState = asyncResult.AsyncState :?> State
    let fStream = tempState.FStream
    fStream.EndWrite asyncResult

    // Asynchronously read back the written data.
    fStream.Position <- 0

    let asyncResult =
        fStream.BeginRead(tempState.ReadArray, 0, tempState.ReadArray.Length, AsyncCallback endReadCallback, tempState)

    // Concurrently do other work, such as
    // logging the write operation.
    ()

Private Shared Sub EndWriteCallback(asyncResult As IAsyncResult)
    Dim tempState As State = _
        DirectCast(asyncResult.AsyncState, State)
    Dim fStream As FileStream = tempState.FStream
    fStream.EndWrite(asyncResult)

    ' Asynchronously read back the written data.
    fStream.Position = 0
    asyncResult = fStream.BeginRead( _ 
        tempState.ReadArray, 0 , tempState.ReadArray.Length, _
        AddressOf EndReadCallback, tempState)

    ' Concurrently do other work, such as 
    ' logging the write operation.
End Sub

Remarks

In the .NET Framework 4 and earlier versions, you have to use methods such as BeginWrite and EndWrite to implement asynchronous file operations. These methods are still available in the .NET Framework 4.5 to support legacy code; however, the new async methods, such as ReadAsync, WriteAsync, CopyToAsync, and FlushAsync, help you implement asynchronous file operations more easily.

This method overrides EndWrite.

EndWrite must be called exactly once on every IAsyncResult from BeginWrite. EndWrite will block until the I/O operation has completed.

Applies to

See also