哪位老大知道什么控件可以用来接收多播（组播）信息？如何使用？有例子最好。(300分)

哪位老大知道什么控件可以用来接收多播（组播）信息？如何使用？有例子最好。

你说清楚一点嘛！多描述一点又不会死。

windos 9x下不支持多播。

To 呆非4:
真的吗？我只是想收这些信息而已

To hnlygtjj:
不是我不想多说，只是并不是一两句话能说清楚，如果你做过这方面的程序，那你肯定
很清楚，否则，即使我把整个通讯协议都翻出来，你还是不明白。另外，奉劝一句，以后
最好注意一下言辞，与人与己都有好处。

叙述一下你的目的吧，解决的办法肯定有，只是想实现什么，然后是怎么去实现罢了。

提前

高深问题知道的人太少，而知道的又不发表言论，真是......[!]

还没碰到过类似控件,不过可以下到WinSock2的Delphi声明单元.
jedi就有.

indy好象有支持多播的控件，找来看看，不过最好自己写一个控件，简单的写一个，不难做

unit MulticastSocket;

{
* 多址广播控件
* 本文件提取自 U_UDPSock.pas
* 整理于2001年11月17~2001年11月18日
* 关于 NB30 单元，主要用于
* "取得本地计算机所有的MAC地址"
* procedure LocalMAC(slMac : TStringList);
* 所以被我注释掉了
* 并不影响使用
}

interface

uses
Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
WinSock;//, NB30;

const
MINBUFFERSIZE = 2048;
DEFAULTBUFFERSIZE = 16384;
MAXBUFFERSIZE = 63488; //62*1024
MULTICAST_TTL = IP_DEFAULT_MULTICAST_TTL;
MAX_MULTICAST_TTL = 128;

type
PIP_mreq = ^TIP_mreq;
TIP_mreq = record
imr_multiaddr : in_addr;
imr_interface : in_addr;
end;

TAPInAddr = Array [0..10] of PInAddr; // array of pInaddr
PAPInAddr = ^TAPInaddr; // pointer of Array

(*
PASTAT = ^TASTAT;
TASTAT = record
adapter : TAdapterStatus;
name_buf : TNameBuffer;
end;
*)

TUDPOnRecv = procedure (buffer: Pointer; len: integer; fromIP: string; fromPort: u_Short) of Object;

//接收数据线程
TUDPRecvThd = class(TThread)
private
fSocks : TSocket;
fBufSize : integer;
fOnRecv : TUDPOnRecv;
protected
procedure Execute ; override;
public
constructor Create(var Socks : TSocket; OnRecv : TUDPOnRecv; BufSize : integer);
end;

type
TMulticastSocket = class(TComponent)
private
{ Private declarations }
fActived : Boolean; {是否激活}

fsock : TSocket; {socket}
fRecvThd : TUDPRecvThd; {接收线程}
fMCReq : TIP_mreq; {记录加入的组地址，释放资源时用}
fSendBufSize: integer; {发送缓冲区大小}
fRecvBufSize: integer; {接收缓冲区大小}
fLocalIP : String; {本地IP地址}
fAddrTo : TSockAddr; {发送IP地址}
fCanRead : Boolean; {可以读取数据}
fCanWrite : Boolean; {可以发送数据}
fTTL : integer; {Time To Live,生存时间,即可以跨越的网关数}
fGroupAddress:String; {组地址}
fGroupPort : integer; {组端口}
//fRecvState : Boolean; {接收线程是否启动}
fOnRecv : TUDPOnRecv; {响应的事件}

{组地址}
procedure SetGroupAddress(addr:String);
{组端口}
procedure SetGroupPort(port:integer);
{读}
procedure SetCanRead(CanRead:Boolean);
{写}
procedure SetCanWrite(CanWrite:Boolean);
{发送缓冲区大小}
procedure SetSendBufSize(SendBufSize:integer);
{接收缓冲区大小}
procedure SetRecvBufSize(RecvBufSize:integer);
{本地IP地址}
procedure SetLocalIP(addr:String);
{是否激活}
procedure SetActived(const Value: Boolean);
{Time To Live,生存时间,即可以跨越的网关数}
procedure SetTTL(const Value: integer);

{改变响应事件的限制}
//procedure SetOnRecv(const Value: Boolean);
procedure SetOnRecv(const Value: TUDPOnRecv);

{Local IP set valid?}
{参数为''的话，就得到默认IP}
function LocalIPValid(var LocalIP:String) : Boolean;

{设置Socket可以接收数据}
function EnabledListen:Boolean;
{设置Socket不能接收数据}
procedure DisabledListen;
{设置Socket可以发送数据}
function EnabledSend:Boolean;
protected
{ Protected declarations }
public
{ Public declarations }
function Close:Boolean;
function Send(buffer : Pointer; len : integer ; Flag : integer = 0) : Boolean;
function AddToGroup : integer;
procedure StartReceive;

{取得本地计算机所有的IP地址}
procedure LocalIPs(slIPs : TStringList);
{取得本地计算机所有的MAC地址}
//procedure LocalMAC(slMac : TStringList);

function Connect:Boolean;
function DisConnect:Boolean;
published
{ Published declarations }
property LocalAddress : String read fLocalIP write SetLocalIP nodefault;
property CanRead : Boolean read fCanRead write SetCanRead default true;
property CanWrite : Boolean read fCanWrite write SetCanWrite default true;
property TTL : integer read fTTL write SetTTL default MULTICAST_TTL;
property SendBufSize: integer read fSendBufSize write SetSendBufSize default DEFAULTBUFFERSIZE;
property RecvBufSize: integer read fRecvBufSize write SetRecvBufSize default DEFAULTBUFFERSIZE;
property GroupAddress:String read fGroupAddress write SetGroupAddress nodefault;
property GroupPort:integer read fGroupPort write SetGroupPort default 6000;
property Actived:Boolean read fActived write SetActived default False;

property OnDataArrive:TUDPOnRecv read fOnRecv write SetOnRecv nodefault;

constructor Create(AOwner:TComponent);override;
destructor Destroy;override;
end;

procedure Register;

implementation

var
wsData : TWSAData;

procedure Register;
begin
RegisterComponents('FastNet', [TMulticastSocket]);
end;

{ TMulticastSocket }

function TMulticastSocket.AddToGroup:integer;
var
nReuseAddr : integer;
SockAddrLocal : TSockAddr;
pPE : PProtoEnt;
begin
Result:=-1;

pPE := GetProtoByName('UDP');
//Create Socket
fSock := Socket(AF_INET, SOCK_DGRAM, pPE.p_proto);
if fSock = INVALID_SOCKET then
Exit;

nReuseAddr := 1;
if SetSockOpt(fSock, SOL_SOCKET, SO_REUSEADDR, @nReuseAddr, SizeOf(integer)) = SOCKET_ERROR then
begin
CloseSocket(fSock);
Exit;
end;

//Set Local Address and bind
FillChar(SockAddrLocal, SizeOf(SockAddrLocal), 0);
SockAddrLocal.sin_family := AF_INET;
//发送用0
//SockAddrLocal.sin_port := htons(0);
SockAddrLocal.sin_port := htons(fGroupPort);
SockAddrLocal.sin_addr.S_addr := Inet_Addr(PChar(fLocalIP));
if Bind(fSock, SockAddrLocal, SizeOf(SockAddrLocal)) = SOCKET_ERROR then
begin
CloseSocket(fSock);
Exit;
end;

if fCanWrite then
if not EnabledSend then
Exit;

if fCanRead then
if not EnabledListen then
Exit;

Result:=0;
end;

function TMulticastSocket.Close: Boolean;
begin
//MulticastReceiver
//Exception will be? I don't know
//释放接收数据线程
if fRecvThd <> nil then
begin
fRecvThd.Suspend;
fRecvThd.Free;
fRecvThd := nil;
end;

DisabledListen;
//Close Socket
CloseSocket(fSock);
Result:=True;
end;

constructor TMulticastSocket.Create(AOwner:TComponent);
begin
{这里设置默认属性,我不知道为什么在Default中写的没有效果}
LocalIPValid(fLocalIP);
fCanRead:=True;
fCanWrite:=True;
fSendBufSize:=DEFAULTBUFFERSIZE;
fRecvBufSize:=DEFAULTBUFFERSIZE;
fGroupAddress:='225.0.0.1';
fGroupPort:=6000;
fTTL:=MULTICAST_TTL;
inherited Create(AOwner);
end;

destructor TMulticastSocket.Destroy;
begin
Close;
inherited Destroy;
end;

procedure TMulticastSocket.SetGroupAddress(addr: String);
var
nMCAddr : Cardinal;
begin
if Actived=True then
Exit;

//Multicast address valid?
nMCAddr := ntohl(inet_addr(PChar(addr)));
//though Multicast ip is between 224.0.0.0 to 239.255.255.255
//the 224.0.0.0 to 224.0.0.225 ips are reserved for system
if not ((nMCAddr <= $efffffff) and (nMCAddr >= $e0000100)) then
Exit;
fGroupAddress:=addr;
end;

function TMulticastSocket.Send(bufferointer;len:integer;Flag:integer=0):Boolean;
begin
Result := False;
if not CanWrite then
Exit;
if SendTo(fSock, buffer^, len, Flag{MSG_DONTROUTE}, fAddrTo,
SizeOf(fAddrTo)) <> SOCKET_ERROR then
Result := True;
end;

procedure TMulticastSocket.StartReceive;
begin
if fRecvThd<> nil then
//接收线程已经启动
Exit;
//启动接收线程
if Assigned(fOnRecv) then
fRecvThd := TUDPRecvThd.Create(fSock, fOnRecv, fSendBufSize);
end;

procedure TMulticastSocket.SetCanRead(CanRead: Boolean);
begin
//if Actived=True then
// Exit;
if fCanRead=CanRead then
Exit;

if CanRead then
begin
if not EnabledListen then
Exit;
end else
DisabledListen;

fCanRead:=CanRead;
end;

procedure TMulticastSocket.SetCanWrite(CanWrite: Boolean);
begin
if Actived=True then
Exit;

fCanWrite:=CanWrite;
end;

procedure TMulticastSocket.SetGroupPort(Port: integer);
begin
if Actived=True then
Exit;

fGroupPort:=Port;
end;

procedure TMulticastSocket.SetRecvBufSize(RecvBufSize: integer);
begin
if Actived=True then
Exit;

//Buffer Size Valid?
if not ((RecvBufSize <= MAXBUFFERSIZE) and (RecvBufSize >= MINBUFFERSIZE)) then
Exit;
fRecvBufSize:=RecvBufSize;
end;

procedure TMulticastSocket.SetSendBufSize(SendBufSize: integer);
begin
if Actived=True then
Exit;

//Buffer Size Valid?
if not ((SendBufSize <= MAXBUFFERSIZE) and (SendBufSize >= MINBUFFERSIZE)) then
Exit;
fSendBufSize:=SendBufSize;
end;

function TMulticastSocket.LocalIPValid(var LocalIP:String): Boolean;
var
i : integer;
slLocalIPs : TStringList;
begin
Result := False;
slLocalIPs := TStringList.Create;
Self.LocalIPs(slLocalIPs);
if slLocalIPs.Count = 0 then
begin
slLocalIPs.Free;
Exit;
end;

if LocalIP = '' then
begin
LocalIP := slLocalIPs[0]; //Default Interface
Result := True;
end else
for i:=0 to slLocalIPs.Count-1 do
if Trim(slLocalIPs) = Trim(LocalIP) then
begin
Result := True;
Break;
end;
slLocalIPs.Free;
end;

procedure TMulticastSocket.SetLocalIP(addr: String);
begin
if Actived=True then
Exit;

//Local IP set valid?
if not LocalIPValid(addr) then
Exit;
fLocalIP:=addr;
end;

procedure TMulticastSocket.LocalIPs(slIPs: TStringList);
var
strLocalHost : string;
pHE : PHostent;
pInAd : PAPInAddr;
saLocal : TSockAddr;
i : integer;
begin
SetLength(strLocalHost, 255);
if GetHostName(PChar(strLocalHost), 254) = SOCKET_ERROR then
Exit;

pHE := GetHostByName(PChar(strLocalHost));
pInAd := PAPInAddr(pHE^.h_addr_list);
saLocal.sin_addr := (pInAd^[0]^);
i := 0;
while True do
begin
slIPs.Add(inet_ntoa(saLocal.sin_addr));
i := i + 1;
if(pInAd^ <> nil) then
saLocal.sin_addr := (pInAd^^) //local host
else
break;
end;
end;

(*
procedure TMulticastSocket.LocalMAC(slMac: TStringList);
var
ncb : TNCB;
adapt : TASTAT;
lanaEnum : TLanaEnum;
i, j : integer;
strPart, strMac : string;
begin
FillChar(ncb, SizeOf(TNCB), 0);
ncb.ncb_command := Char(NCBEnum);
ncb.ncb_buffer := PChar(@lanaEnum);
ncb.ncb_length := SizeOf(TLanaEnum);
Netbios(@ncb);

for i := 0 to integer(lanaEnum.length)-1 do
begin
FillChar(ncb, SizeOf(TNCB), 0);
ncb.ncb_command := Char(NCBReset);
ncb.ncb_lana_num := lanaEnum.lana;
Netbios(@ncb);

FillChar(ncb, SizeOf(TNCB), 0);
ncb.ncb_command := Chr(NCBAstat);
ncb.ncb_lana_num := lanaEnum.lana;
ncb.ncb_callname := '* ';
ncb.ncb_buffer := PChar(@adapt);
ncb.ncb_length := SizeOf(TASTAT);
if Netbios(@ncb) = Chr(0) then
begin
strMac := '';
for j := 0 to 5 do
begin
strPart := IntToHex(integer(adapt.adapter.adapter_address[j]), 2);
strMac := strMac + strPart + '-';
end;
SetLength(strMac, Length(strMac)-1);
slMac.Add(strMac);
end;
end;
end;*)

procedure TMulticastSocket.SetActived(const Value: Boolean);
begin
if Value=fActived then
//状态未发生变化
Exit;
if Value then
Connect
else
DisConnect;
end;

function TMulticastSocket.Connect: Boolean;
begin
Result:=(AddToGroup=0);
if not Result then
Exit;
if CanRead and Assigned(fOnRecv) then
StartReceive;
fActived:=Result;
end;

function TMulticastSocket.DisConnect: Boolean;
begin
Result:=Close;
if Result then
fActived:=False;
end;

procedure TMulticastSocket.SetOnRecv(const Value: TUDPOnRecv);
begin
if Actived and Assigned(fOnRecv) then
//事件已经在运行了
Exit;
fOnRecv := Value;
if Actived then
//已经激活但未设置事件
StartReceive;
end;

procedure TMulticastSocket.SetTTL(const Value: integer);
begin
if Actived
or (Value>MAX_MULTICAST_TTL)
or (Value<0) then
Exit;
fTTL := Value;
end;

function TMulticastSocket.EnabledListen : Boolean;
var
MCReq : TIP_mreq;
begin
Result:=False;

{接收数据缓冲区大小}
if SetSockOpt(fSock, SOL_SOCKET, SO_RCVBUF, @fRecvBufSize, SizeOf(integer)) = SOCKET_ERROR then
begin
CloseSocket(fSock);
Exit;
end;

{加入多址广播组}
MCReq.imr_multiaddr.S_addr := Inet_Addr(PChar(fGroupAddress));
MCReq.imr_interface.S_addr := Inet_Addr(PChar(fLocalIP));
if SetSockOpt(fSock, IPPROTO_IP, IP_ADD_MEMBERSHIP, @MCReq,
SizeOf(TIP_mreq)) = SOCKET_ERROR then
begin
CloseSocket(fSock);
Exit;
end;
fMCReq := MCReq;

if Actived and Assigned(fOnRecv) then
StartReceive;

Result:=True;
end;

function TMulticastSocket.EnabledSend: Boolean;
var
SockAddrLocal, SockAddrRemote : TSockAddr;
begin
Result:=False;

FillChar(SockAddrLocal, SizeOf(SockAddrLocal), 0);
SockAddrLocal.sin_family := AF_INET;
SockAddrLocal.sin_port := htons(fGroupPort);
SockAddrLocal.sin_addr.S_addr := Inet_Addr(PChar(fLocalIP));

{发送数据缓冲区大小}
if SetSockOpt(fSock, SOL_SOCKET, SO_SNDBUF, @fSendBufSize, SizeOf(integer)) = SOCKET_ERROR then
begin
CloseSocket(fSock);
Exit;
end;
{IP multicast output interface}
if SetSockOpt(fSock, IPPROTO_IP, IP_MULTICAST_IF, @(SockAddrLocal.sin_addr),
SizeOf(In_Addr)) = SOCKET_ERROR then
begin
CloseSocket(fSock);
Exit;
end;
{设置Time To Livw}
if SetSockOpt(fSock, IPPROTO_IP, IP_MULTICAST_TTL, @fTTL, SizeOf(integer)) = SOCKET_ERROR then
begin
CloseSocket(fSock);
Exit;
end;

{设置发送的目的位置到fAddrTo中}
FillChar(SockAddrRemote, SizeOf(SockAddrRemote), 0);
SockAddrRemote.sin_family := AF_INET;
SockAddrRemote.sin_port := htons(fGroupPort);
SockAddrRemote.sin_addr.S_addr := Inet_Addr(PChar(fGroupAddress));
fAddrTo := SockAddrRemote;

Result:=True;
end;

procedure TMulticastSocket.DisabledListen;
begin
SetSockOpt(fSock, IPPROTO_IP, IP_DROP_MEMBERSHIP, @fMCReq, SizeOf(fMCReq));
end;

{ TUDPRecvThd }

constructor TUDPRecvThd.Create(var Socks: TSocket; OnRecv: TUDPOnRecv;
BufSize: integer);
begin
fSocks := Socks;
fOnRecv := OnRecv;
fBufSize := BufSize;
FreeOnTerminate := True;
inherited Create(False);
end;

procedure TUDPRecvThd.Execute;
var
readFDs : TFDSet;
nRecved, nAddrLen: integer;
buf : array [0..MAXBUFFERSIZE] of Byte;
SockFrom : TSockAddr;
begin
Priority := tpHighest;
while not Terminated do
begin
nAddrLen := SizeOf(SockFrom);
FD_ZERO(readFDs);
FD_SET(fSocks, readFDs);
Select(0, @readFDs, nil, nil, nil);
if FD_ISSET(fSocks, readFDs) then
begin
nRecved := RecvFrom(fSocks, buf, fBufSize, 0, SockFrom, nAddrLen);
if Assigned(fOnRecv) then
fOnRecv(@buf, nRecved, string(Inet_Ntoa(SockFrom.sin_addr)),
Cardinal(Ntohs(SockFrom.sin_port)));
end;
end;
end;

initialization
if WSAStartup(MakeWord(2,0), wsData)<>0 then
raise Exception.Create('Cannot use the socket service!');

finalization
WSACleanup;

end.

谁说98不支持多播的?其实我觉得最好成绩自己写一个其实并不复杂呀!

多人接受答案了。