java udp 广播

来源：互联网发布：php调用lua 编辑：程序博客网时间：2024/04/29 22:51

udp 是一种网络通信协议，不需要客户端和服务器端建立连接即可进行通讯功能。相对于Tcp协议它有着tcp用很多优点，例如广播功能。udp的广播功能可以指定特定网段进行广播内容，而无需知道接收者是谁，只有接受者在广播范围内即可接收广播内容。其实基于这个功能可以实现一个局域网群聊室的功能。

udp广播发送有两种形式，

方式一：通过DatagramSocket实现

方式二：通过MulticastSocket 实现

方式一：demo;

1,数据发送端：

[java] view plaincopy
import java.io.IOException;  
import java.net.DatagramPacket;  
import java.net.DatagramSocket;  
import java.net.InetAddress;  
import java.net.SocketException;  
import java.net.UnknownHostException;  
  
  
public class SendIP {  
  
    public static void main(String args[]) {  
        new SendIP().lanchApp();  
     }  
      
    private void lanchApp(){  
        SendThread th=new SendThread();  
        th.start();  
    }  
      
      
    private class SendThread extends Thread{  
        @Override  
        public void run() {  
            while(true){  
                try {  
                    Thread.sleep(1000);  
                } catch (InterruptedException e) {  
                    e.printStackTrace();  
                }  
                try {  
                    BroadcastIP();  
                } catch (Exception e) {  
                    e.printStackTrace();  
                }  
            }  
        }  
          
        private void BroadcastIP()throws Exception{  
             DatagramSocket dgSocket=new DatagramSocket();  
              byte b[]="你好，这是我发给你的消息".getBytes();  
              DatagramPacket dgPacket=new DatagramPacket(b,b.length,InetAddress.getByName("255.255.255.255"),8989);  
              dgSocket.send(dgPacket);  
              dgSocket.close();  
              System.out.println("send message is ok.");  
        }  
    }  
      
}  

2，数据接收端：

[java] view plaincopy
import java.net.DatagramPacket;  
import java.net.DatagramSocket;  
import java.net.SocketException;  
import java.util.regex.Matcher;  
import java.util.regex.Pattern;  
  
    public class SearchIP{  
          
         public static void main(String args[])throws Exception{  
           
             new SearchIP().lanchApp();  
         }  
           
         private void lanchApp(){  
             receiveThread th=new receiveThread();  
                th.start();  
            }  
           
         private class receiveThread extends Thread{  
             @Override  
                public void run() {  
                    while(true){  
                        try {  
                            Thread.sleep(1000);  
                        } catch (InterruptedException e) {  
                            e.printStackTrace();  
                        }  
                        try {  
                            receiveIP();  
                        } catch (Exception e) {  
                            e.printStackTrace();  
                        }  
                    }  
             }  
               
            private void receiveIP() throws Exception{  
                 DatagramSocket dgSocket=new DatagramSocket(8989);  
                  byte[] by=new byte[1024];  
                  DatagramPacket packet=new DatagramPacket(by,by.length);  
                  dgSocket.receive(packet);  
                    
                  String str=new String(packet.getData(),0,packet.getLength());  
                    
                  System.out.println("接收到数据大小:"+str.length());  
                  System.out.println("接收到的数据为："+str);  
                  dgSocket.close();  
                  System.out.println("recevied message is ok.");  
             }  
         }  
  
               
    }  

方式二demo;

1,数据发送端：

[java] view plaincopy
import java.io.IOException;  
import java.net.DatagramPacket;  
import java.net.InetAddress;  
import java.net.MulticastSocket;  
  
  
public class MulBroadcast extends Thread{  
  
    String info ="节目预告： 恭喜您中500w彩票了";    
    int port =9898;    
    InetAddress address;  
    MulticastSocket socket;    
      
   public MulBroadcast(){  
       try{  
       address=InetAddress.getByName("233.0.0.0");    
       socket=new MulticastSocket(port);    
       socket.setTimeToLive(1);    
       socket.joinGroup(address);    
       }catch(IOException e){  
           e.printStackTrace();  
       }  
    }  
     
    @Override   //最简单的方法也就是建立一个线程来运行     
    public void run(){    
        while(true){    
            byte[] data=info.getBytes();    
            DatagramPacket packet=new DatagramPacket(data,data.length,address,port);    
              
            try {    
                socket.send(packet);   
                Thread.sleep(3000);  
            } catch (Exception e) {    
                e.printStackTrace();    
            }    
            System.out.println("消息已发送：");    
        }    
    }    
      
    public static void main(String[] args){    
        new MulBroadcast().start();  
    }    
      
}  

2，数据接收端：

[java] view plaincopy
import java.io.IOException;  
import java.net.DatagramPacket;  
import java.net.InetAddress;  
import java.net.MulticastSocket;  
  
  
public class MulReceiverIP extends Thread{  
  
        int port=9898;    
        InetAddress group;    
        MulticastSocket socket; //socket sends and receives the packet.     
        DatagramPacket packet;   
        byte[] buf=new byte[30];// If the message is longer than the packet's length, the message is truncated.  
          
    public MulReceiverIP(){  
         try {    
                socket=new MulticastSocket(port);  
                
                group=InetAddress.getByName("233.0.0.0");   
                socket.joinGroup(group);    //加入广播组,加入group后,socket发送的数据报,可以被加入到group中的成员接收到。  
                packet=new DatagramPacket(buf,buf.length);    
                    
            } catch (IOException e) {    
                e.printStackTrace();    
            }    
    }  
      
      @Override    
        public void run(){    
            while(true){    
                try {    
                    socket.receive(packet);    
                } catch (IOException e) {    
                    e.printStackTrace();    
                }    
                //      String message=new String(buf);     
               String message=new String(packet.getData(),0,packet.getLength());//very important !!     
               System.out.println("接受消息内容: "+message);  
                 
            }    
        }    
        
      public static void main(String[] args) {  
            new MulReceiverIP().start();  
    }  
        
}  

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