UDP远程传送文件 重复传送不了？


以下为发送端的代码unit UnitClient;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, IdBaseComponent, IdComponent, IdUDPBase, IdUDPClient,
  IdAntiFreezeBase, IdAntiFreeze, Gauges;type
  TFormClient = class(TForm)
    IdUDPClient1: TIdUDPClient;
    Edit1: TEdit;
    Label1: TLabel;
    Button1: TButton;
    OpenDialog1: TOpenDialog;
    Gauge1: TGauge;
    procedure Button1Click(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  FormClient: TFormClient;implementation{$R *.dfm}procedure TFormClient.Button1Click(Sender: TObject);
Var  ReceivedString:String;
  Mem:TFileStream;
  p:Array[0..1023] of byte;
  Posi,Len:Integer;
begin
  if OpenDialog1.Execute then
  begin
    IdUDPClient1.Host:=Edit1.Text;
    IdUDPClient1.Active:=True;
    IdUDPClient1.Send('Send file:File Name:'+OpenDialog1.FileName);
    ReceivedString := IdUDPClient1.ReceiveString();
    if UpperCase(ReceivedString)='RECIVED FILE NAME OK!' then
    begin
      Mem:=TFileStream.Create(OpenDialog1.FileName,fmOpenRead);
      try
        Posi:=0;
        IdUDPClient1.Send('Send File:File Length:'+IntToStr(Mem.Size));
        ReceivedString := IdUDPClient1.ReceiveString();
        if UpperCase(ReceivedString)='RECIVED FILE LENGTH OK!' then
        begin
          While Posi<Mem.Size do//一次只发1024个字节,字节数不能太多,不过应该还可以增加一些.
          begin
            Len:=1024;
            if Mem.Size-Posi<1024 then
              Len:=Mem.Size-Posi;
            Mem.Read(p,Len);
            IdUDPClient1.SendBuffer(P,Len);
            Inc(Posi,Len);
            Gauge1.Progress:=Round(Posi/Mem.Size*100);
            ReceivedString := IdUDPClient1.ReceiveString();
            if UpperCase(ReceivedString)<>'RECIVED FILE PACKAGE OK!' then
              Break;
            Application.ProcessMessages;
          end;
          IdUDPClient1.Send('Send File:File End!');
        end else
          ShowMessage('Send file cancel!');
      finally
        Mem.Free;
      end;
    end;
  end;
end;end.
以下为接收端的代码unit UnitServer;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, IdBaseComponent, IdComponent, IdUDPBase, IdUDPServer,IdSocketHandle,
  IdAntiFreezeBase, IdAntiFreeze, Gauges;type
  TFormServer = class(TForm)
    IdUDPServer1: TIdUDPServer;
    SaveDialog1: TSaveDialog;
    Gauge1: TGauge;
    procedure IdUDPServer1UDPRead(Sender: TObject; AData: TStream;ABinding: TIdSocketHandle);
    procedure FormCreate(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
    FileName:String;
    FileSize:Integer;
    Mem:TFileStream;
    { Private declarations }
  public
    { Public declarations }
  end;var
  FormServer: TFormServer;implementation{$R *.dfm}procedure TFormServer.IdUDPServer1UDPRead(Sender: TObject; AData: TStream;
  ABinding: TIdSocketHandle);
Var Str:String;
begin
  AData.Seek(0,0);
  SetLength(Str,AData.Size);
  AData.Read(Str[1],AData.Size);
  if Pos('Send file:File Name:',Str)>0 then
  begin
    Delete(Str,1,Length('Send file:File Name:'));
    FileName:=Str;
    Str:='Recived File Name OK!';
    ABinding.SendTo(ABinding.PeerIP, ABinding.PeerPort, Str[1], Length(Str));
  end else if Pos('Send File:File Length:',Str)>0 then
  begin
    Delete(Str,1,Length('Send File:File Length:'));
    FileSize:=StrToIntDef(Str,0);
    SaveDialog1.FileName:=FileName;
    if SaveDialog1.Execute then
    begin
      FileName:=SaveDialog1.FileName;
      if FileExists(FileName) then
        DeleteFile(FileName);
      if Mem<>nil then
      begin
        Mem.Free;
        Mem:=nil;
      end;
      if not FileExists(FileName) then
        Mem:=TFileStream.Create(FileName,fmOpenReadWrite or fmCreate)
      else
        Mem:=TFileStream.Create(FileName,fmOpenReadWrite);
      Str:='Recived File Length OK!';
      ABinding.SendTo(ABinding.PeerIP, ABinding.PeerPort, Str[1], Length(Str));
    end else
    begin
      Str:='Recived File Length Cancel!';
      ABinding.SendTo(ABinding.PeerIP, ABinding.PeerPort, Str[1], Length(Str));
    end;
  end else if Pos('Send File:File End!',Str)>0 then
  begin
    if Mem<>nil then
    begin
      Mem.Free;
      Mem:=nil;
      Str:='Recived File OK!';
      ABinding.SendTo(ABinding.PeerIP, ABinding.PeerPort, Str[1], Length(Str));
    end;
    FileName:='';
    FileSize:=0;
  end
  else
  begin
    if Mem<>nil then
    begin
      Mem.Seek(0,2);
      AData.Seek(0,0);
      Mem.CopyFrom(AData,AData.Size);
      Gauge1.Progress:=Round(Mem.Size/FileSize*100);
      Str:='Recived File Package OK!';
      ABinding.SendTo(ABinding.PeerIP, ABinding.PeerPort, Str[1], Length(Str));
      Application.ProcessMessages;
    end;
  end;
end;procedure TFormServer.FormCreate(Sender: TObject);
begin
  IdUDPServer1.Active:=True;
  FileName:='';
  FileSize:=0;
  Mem:=nil;
end;procedure TFormServer.FormDestroy(Sender: TObject);
begin
  if Mem<>nil then
    Mem.Free;
end;end.以上代码只能发送一次，需要关掉发送端再打开才能发送第二次，请问如何修改让他能多次发送啊？