| Description |
Normally, you would allow the callback method of an asynchronous write to be called. If you need to wait until this happens in the main thread of operation, then call EndWrite.
The AsynResult parameter should be supplied with the value returned by the BeginWrite you want to wait for.
|
| | Notes | The callback method will be called asynchronously to the main thread - see the example for the effect of this.
|
|
| Microsoft MSDN Links |
System.IO
System.IO.FileStream
|
|
|
| A simple example |
program Project1;
{$APPTYPE CONSOLE}
uses
System.IO,
System.Runtime.Remoting.Messaging;
var
Stream : System.IO.FileStream;
ByteArray : Array of Byte;
ByteAsInt : Integer;
AsyncRes : IAsyncResult;
Index : Integer;
procedure WriteDone(AsyncResult : IAsyncResult);
var
Index : Integer;
begin
Console.WriteLine('Write is finished :');
Console.WriteLine;
end;
begin
// Create our File Stream
Stream := System.IO.FileStream.Create('C:\DelphiBasics.txt', FileMode.Create);
// Create our byte array
SetLength(ByteArray, 10);
// And fill it
ByteArray[0] := 65; // Ord(65) = 'A'
ByteArray[1] := 66;
ByteArray[2] := 67;
ByteArray[3] := 68;
ByteArray[4] := 69;
ByteArray[5] := 70;
ByteArray[6] := 71;
ByteArray[7] := 72;
ByteArray[8] := 73;
ByteArray[9] := 74;
// Write to the stream from the array asynchronously
AsyncRes := Stream.BeginWrite(ByteArray, 0, 10, WriteDone, TObject.Create);
// Wait for the read to end
Console.WriteLine;
Console.WriteLine('Waiting in main thread for write to complete');
Console.WriteLine;
Stream.EndWrite(AsyncRes);
// Display the stream contents
Stream.Seek(0, SeekOrigin.Begin);
ByteAsInt := Stream.ReadByte;
while ByteAsInt > 0 do
begin
Console.WriteLine(Char(ByteAsInt));
ByteAsInt := Stream.ReadByte;
end;
// Close the file stream
Stream.Close;
Console.Readline;
end.
| | Show full unit code |
Waiting in main thread for write to complete
A
B
C
D
E
F
G
Write is finished :
H
I
J
|
| |
|
|
|