一、MulticastSocket類
多點傳播也稱為多點傳播，就是給一組特定的主機(多點傳播組)發送資料。多點傳播通過多點傳播資料報套接MulticastSocket類來實作
重要的構造方法：
MulticastSocket() 建立多點傳播套接字
MulticastSocket(int port) 建立多點傳播套接字并将其綁定到特定端口
MulticastSocket(SocketAddress bindaddr) 建立綁定到指定套接字位址的MulticastSocket
常用的方法：
void joinGroup(InetAddress meastaddr) 加入多點傳播組
void leaveGroup(InetAddress meastaddr) 離開多點傳播組
void send(DatagramPacket p) 從此套接字發送資料包
public void receive(DatagramPacket p) 從此套接字接收資料包
二、代碼實作
發送端程式設計：發送端将在廣播位址為“230.198.112.0”，9876号端口處發送廣播資訊
package org.multicastsocket;
import java.net.InetAddress;
import java.net.DatagramPacket;
import java.net.MulticastSocket;
public class multicastDemo01 extends Thread
{
String message[] = {"失物招領：有誰在操場丢失鑰匙一串，請到學校廣播站認領。","大風藍色預警：預計今天下午有北風6級，請有關機關和人員做好防範準備。"};
int port = 9876;//多點傳播的端口
InetAddress group = null;//多點傳播的組位址
MulticastSocket mutiSocket = null;//多點傳播套接字
public multicastDemo01()
{
try
{
group = InetAddress.getByName("230.198.112.0");//設定廣播組位址
mutiSocket = new MulticastSocket(port);//多點廣播套接字将在port端口廣播
mutiSocket.setTimeToLive(1);
mutiSocket.joinGroup(group);
}
catch (Exception e)
{
System.out.println("Error:"+e);
}
}
public void run()
{
while(true)
{
try
{
DatagramPacket packet = null;
for(String msg : message)//循環發送每條廣播資訊
{
byte buff[] = msg.getBytes();
packet = new DatagramPacket(buff, buff.length,group,port);
System.out.println(new String(buff));
mutiSocket.send(packet);
sleep(2000);
}
}
catch (Exception e)
{
System.out.println("Error:"+e);
}
}
}
public static void main(String[] args)
{
new multicastDemo01().start();
}
}
接收端程式設計：接收端主機将加入廣播位址為“230.198.112.0”，并在9876号端口處接收廣播資訊
package org.multicastsocket;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.net.InetAddress;
import java.net.DatagramPacket;
import java.net.MulticastSocket;
public class multicastDemo02 extends JFrame implements Runnable,ActionListener
{
private static final long serialVersionUID = -5923790809266120014L;
int port;
InetAddress group = null;
MulticastSocket socket = null;
JButton startButton;
JButton stopButton;
JButton cleanButton;
JTextArea currentMsg;
JTextArea receiveMsg;
Thread thread;
boolean isStop = false;//停止接收廣播資訊的标志
public multicastDemo02()
{
setTitle("接收廣播資訊");
Container container = this.getContentPane();
startButton = new JButton("開始接收");
stopButton = new JButton("停止接收");
cleanButton = new JButton("清空資訊");
startButton.addActionListener(this);
stopButton.addActionListener(this);
cleanButton.addActionListener(this);
currentMsg = new JTextArea(3,20);//建立3行20列的多行文本框
currentMsg.setForeground(Color.red);//設定字型顔色為紅色
receiveMsg = new JTextArea(8,20);//預設字型顔色為黑色
container.setLayout(new BorderLayout());
JSplitPane sp = new JSplitPane(JSplitPane.VERTICAL_SPLIT);//建立一帶水準分隔條的面闆
JScrollPane currScrollPane = new JScrollPane();
currScrollPane.setViewportView(currentMsg);
JScrollPane recvScrollPane = new JScrollPane();
recvScrollPane.setViewportView(receiveMsg);
currentMsg.setEditable(false);
receiveMsg.setEditable(false);
sp.add(currScrollPane);
sp.add(recvScrollPane);
container.add(sp,BorderLayout.CENTER);
JPanel bottomJPanel = new JPanel();
bottomJPanel.add(startButton);
bottomJPanel.add(stopButton);
bottomJPanel.add(cleanButton);
container.add(bottomJPanel,BorderLayout.SOUTH);
setSize(500,400);
setVisible(true);
thread = new Thread(this);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
port = 9876;
try
{
group = InetAddress.getByName("230.198.112.0");
socket = new MulticastSocket(port);
socket.joinGroup(group);
}
catch (Exception e)
{
}
}
public void actionPerformed(ActionEvent e1)
{
if(e1.getSource() == startButton)
{
startButton.setEnabled(false);
stopButton.setEnabled(true);
if(!(thread.isAlive()))
{
thread = new Thread(this);
}
try
{
thread.start();
isStop = false;
}
catch (Exception ee)
{
}
}
if(e1.getSource() == stopButton)
{
startButton.setEnabled(true);
stopButton.setEnabled(false);
isStop = true;
}
if(e1.getSource() == cleanButton)
{
receiveMsg.setText("");
}
}
public void run()
{
while(true)
{
byte buff[] = new byte[8192];
DatagramPacket packet = null;
packet = new DatagramPacket(buff, buff.length,group,port);
try
{
socket.receive(packet);
String message = new String(packet.getData(),0,packet.getLength());
currentMsg.setText("正在接收的内容：\n"+message);
receiveMsg.append(message+"\n");
}
catch (Exception e)
{
}
if(isStop == true)
{
break;
}
}
}
public static void main(String[] args)
{
new multicastDemo02();
}
}
三、 效果展示
