想用indy的UDP组件做一个局域网的聊天程序，用户上线怎么做呢？

Question

想用Indy的UDP组件自己做一个类似QQ的局域网聊天程序，大家上班时用。现在的问题是当用户上线时是发个广播消息吗？让在线人都知道，如果是的话，这个广播消息怎么发呢？

Answer 1

delphi7 
indy9unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, IdUDPClient, IdBaseComponent, IdComponent, IdUDPBase,
  IdUDPServer,IdStack,IdSocketHandle;type
  TForm1 = class(TForm)
    Button1: TButton;
    IdUDPServer1: TIdUDPServer;
    IdUDPClient1: TIdUDPClient;
    ListBox1: TListBox;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure IdUDPServer1UDPRead(Sender: TObject; AData: TStream;
      ABinding: TIdSocketHandle);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);
begin
//--xxx.xxx.xxx.255 是你的广播地址
self.IdUDPClient1.Send('192.168.1.255',99999,GStack.LocalAddress);
end;procedure TForm1.FormCreate(Sender: TObject);
begin
self.IdUDPServer1.DefaultPort:=99999;
self.IdUDPServer1.Active:=True;
end;procedure TForm1.IdUDPServer1UDPRead(Sender: TObject; AData: TStream;
  ABinding: TIdSocketHandle);
var
  strStream:TStringStream;
begin
  strStream:= TStringStream.Create('');
  try
    strStream.CopyFrom(AData,AData.Size);
    listbox1.Items.Add(strStream.DataString+'上线了');
  except
  end;
end;end.

Answer 2

procedure TForm1.IdUDPServer1UDPRead(Sender: TObject; AData: TStream;
  ABinding: TIdSocketHandle);
var
  strStream:TStringStream;
begin
  strStream:= TStringStream.Create('');
  try
    strStream.CopyFrom(AData,AData.Size);
    listbox1.Items.Add(strStream.DataString+'上线了');
  except
  end;
  strStream.Free;
end;

Answer 3

//--xxx.xxx.xxx.255 是你的广播地址
是什么意思？是我的iP地址吗？
你这种方法是向一个地址广播吗？我的意思是向所有iP地址广播，是不是UDP协议有这个功能呢？

Answer 4

IdUDPServer1.BroadCastEnabled:=true;
IdUDPServer1.BrodCast(Port,aMessage)

Answer 5

delphi7 
indy9unit Unit1;interfaceuses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, StdCtrls, IdUDPClient, IdBaseComponent, IdComponent, IdUDPBase,
  IdUDPServer,IdStack,IdSocketHandle;type
  TForm1 = class(TForm)
    Button1: TButton;
    IdUDPServer1: TIdUDPServer;
    IdUDPClient1: TIdUDPClient;
    ListBox1: TListBox;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure IdUDPServer1UDPRead(Sender: TObject; AData: TStream;
      ABinding: TIdSocketHandle);
  private
    { Private declarations }
  public
    { Public declarations }
  end;var
  Form1: TForm1;implementation{$R *.dfm}procedure TForm1.Button1Click(Sender: TObject);
begin
//--xxx.xxx.xxx.255 是你的广播地址
self.IdUDPClient1.Send('192.168.1.255',99999,GStack.LocalAddress);
end;procedure TForm1.FormCreate(Sender: TObject);
begin
self.IdUDPServer1.DefaultPort:=99999;
self.IdUDPServer1.Active:=True;
end;procedure TForm1.IdUDPServer1UDPRead(Sender: TObject; AData: TStream;
  ABinding: TIdSocketHandle);
var
  strStream:TStringStream;
begin
  strStream:= TStringStream.Create('');
  try
    strStream.CopyFrom(AData,AData.Size);
    listbox1.Items.Add(strStream.DataString+'上线了');
  except
  end;
end;end.

Answer 6

这种方法要有服务器端，而且最好自己定个协议建议使用idtcpserver,idtcpclient