使用delphi的indy9的TidUDPServer控件，编写一个多线程读取udp的完整程序，要求不能使用高版本的功能，必须使用indy控件，并提供完整的调用代码

以下是使用Delphi的Indy 9的TIdUDPServer控件编写多线程读取UDP的程序示例：

unit UdpServer;

interface

uses
  Classes, IdGlobal, IdSocketHandle, IdUDPServer, SysUtils;

type
  TMyUdpServer = class(TThread)
  private
    FPort: Integer;
    FServer: TIdUDPServer;
    procedure HandleUDP(AData: TStream; ABinding: TIdSocketHandle);
  protected
    procedure Execute; override;
  public
    constructor Create(APort: Integer);
    destructor Destroy; override;
  end;

implementation

constructor TMyUdpServer.Create(APort: Integer);
begin
  inherited Create(False);
  FPort := APort;
end;

destructor TMyUdpServer.Destroy;
begin
  if Assigned(FServer) then
  begin
    FServer.Active := False;
    FreeAndNil(FServer);
  end;
  inherited Destroy;
end;

procedure TMyUdpServer.Execute;
begin
  FServer := TIdUDPServer.Create(nil);
  try
    FServer.Bindings.Add.IPVersion := Id_IPv4;
    FServer.Bindings.Add.Port := FPort;
    FServer.OnUDPRead := HandleUDP;
    FServer.Active := True;
    while not Terminated do
    begin
      Sleep(5);
    end;
  except
    on E: Exception do
    begin
      // handle exception
    end;
  end;
end;

procedure TMyUdpServer.HandleUDP(AData: TStream; ABinding: TIdSocketHandle);
var
  S: String;
begin
  SetLength(S, AData.Size);
  AData.ReadBuffer(S[1], AData.Size);
  // do something with S
end;

end.

使用示例：

procedure TForm1.FormCreate(Sender: TObject);
begin
  TMyUdpServer.Create(8888);
end;

以上代码创建了一个UDP服务器，监听端口号为8888，当接收到UDP数据时，将调用HandleUDP方法进行处理。HandleUDP方法中的代码可以根据实际需求进行修改。