TCP 服务器每 8 毫秒连续发送一次数据帧。我想编写一个能够接收这些数据帧的客户端。 Indy 9 中是否有任何程序可以知道缓冲区中是否有可用数据?
我当前的程序如下(我正在使用线程):
procedure TThreadRead.Execute;
var
buffer: array [0..755] of byte;
//s1: string;
//i: integer;
begin
IdTCPClient1.RecvBufferSize:= 756;
IdTCPClient1.Connect;
while Terminated = false do
begin
if IdTCPClient1.InputBuffer.Size = 0 then
IdTCPClient1.ReadFromStack(True,0,False);
while IdTCPClient1.InputBuffer.Size > 0 do
begin
ReadBuffer(buffer, FClient.InputBuffer.Size);
//s1:= '';
//For i:=0 To Length(buffer)-1 Do
// s1:=s1+IntToHex(Ord(buffer[i]),2); //Read values-->global var
//Form1.Memo1.Text:=s1;
end;
end;
end;
是否有更有效的解决方案来连续读取 TCP 数据(例如 UDP 中的 onread 事件)?
提前致谢。
TIdTCPClient
不是异步组件。它不会告诉您数据何时到达。您需要使用计时器或线程定期轮询套接字以获取新数据(TIdUDPServer
使用内部线程来触发它OnUDPRead
事件),例如:
procedure TForm1.Button1Click(Sender: TObject);
begin
IdTCPClient1.Connect;
Timer1.Enabled := True;
end;
procedure TForm1.Button2Click(Sender: TObject);
begin
Timer1.Enabled := False;
IdTCPClient1.Disconnect;
end;
procedure TForm1.Timer1Timer(Sender: TObject);
var
s1: string;
begin
s1 := IdTCPClient1.CurrentReadBuffer;
...
end;
照这样说,CurrentReadBuffer()
通常不是使用的最佳选择。通常你会做类似这样的事情:
procedure TForm1.Timer1Timer(Sender: TObject);
begin
Timer1.Enabled := False;
IdTCPClient1.ReadFromStack(True, 0, False);
while IdTCPClient1.InputBuffer.Size > 0 do
begin
// read one complete frame and process as needed ...
end;
Timer1.Enabled := True;
end;
Update:鉴于有关框架结构和切换到线程的新信息,您应该这样做:
procedure TThreadRead.Execute;
var
buffer: array of Byte;
numbytes: Integer;
begin
SetLength(buffer, 0);
IdTCPClient1.Connect;
try
while not Terminated do
begin
numbytes := StrToInt('$' + IdTCPClient1.ReadString(8)) - 8;
if numbytes <> Length(buffer) then
SetLength(buffer, numbytes);
if numbytes > 0 then
IdTCPClient1.ReadBuffer(buffer[0], numbytes);
// process buffer up to numbytes as needed...
end;
finally
IdTCPClient1.Disconnect;
end;
end;
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