JAVA局域网广播 其他机器收不到。
本人接触JAVA 一个多月了 自己写了个 局域网聊天 传文件 和群聊的小软件。群聊不是用的服务器客户端的模式，而是直接在局域网中用 multiCastSocket进行广播。但是 自己的机器上不管能收到广播，在局域网其他的机器上就收不到。也在网上查了很久，没找到相似的情况。纠结了两天了。于是想在这里来问问大家 代码很长 我贴出个我广播自己在线，和在线用户查询的代码。

//广播自己在线的类

package lMess;

//服务端代码：不断广播--自身信息

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.net.*;

public class BroadCast extends Thread {

String message;

int port = 50611;

InetAddress group = null;

MulticastSocket socket = null;
private javax.swing.JTextField userNameArea;
String ip;

BroadCast(javax.swing.JTextField userNameArea) {
this.userNameArea = userNameArea;
File ipFile = new File("ipBroadCast.ini");
try {
if (ipFile.exists()) {
BufferedReader reader = new BufferedReader(new FileReader(
"ipBroadCast.ini"));
try {
ip = reader.readLine();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
} catch (FileNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
try {
group = InetAddress.getByName(ip);
socket = new MulticastSocket(port);
socket.setTimeToLive(0);
socket.joinGroup(group);

} catch (Exception e) {
}
}

public void run() {
while (true) {
try {
DatagramPacket packet = null;
message = "USER:" + userNameArea.getText() + " @ "
+ InetAddress.getLocalHost();
byte data[] = message.getBytes();
packet = new DatagramPacket(data, data.length, group, port);
System.out.println(new String(data));
socket.send(packet);
sleep(4000);
} catch (Exception e) {
}
}
}

}

//接受广播的类

package lMess;

import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.net.DatagramPacket;
import java.net.InetAddress;
import java.net.MulticastSocket;
import java.net.UnknownHostException;

import javax.swing.JButton;
import javax.swing.JTextArea;

public class UsersFinding implements Runnable {

private javax.swing.JTextArea usersList;

int port = 50611;
InetAddress group = null;
MulticastSocket socket = null;
JButton startReceive, stopReceive;
JTextArea showArea;
Thread thread;
boolean stop = false;
String ip;

public UsersFinding(javax.swing.JTextArea usersList) {
this.usersList = usersList;
File ipFile = new File("ipBroadCast.ini");
try {
if (ipFile.exists()) {
BufferedReader reader = new BufferedReader(new FileReader(
"ipBroadCast.ini"));
try {
ip = reader.readLine();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
} catch (FileNotFoundException e1) {
// TODO Auto-generated catch block
e1.printStackTrace();
}
}

public void run() {

try {
while (true) {
group = InetAddress.getByName(ip);
socket = new MulticastSocket(port);
socket.joinGroup(group);
byte[] buffer = new byte[256];
DatagramPacket dgp = new DatagramPacket(buffer, buffer.length);
socket.receive(dgp);
byte[] getMessage = new byte[dgp.getLength()];
System.arraycopy(dgp.getData(), 0, getMessage, 0,
dgp.getLength());

String get = new String(getMessage);
System.out.println("UsersFinding get the Message:\n" + get);