udp 局域网群聊

UDP:
无连接协议
udp协议发送数据,用的是数据报包的形式。(64KB以内)
 
 
发送端:
1.定义发送的datagramsocket对象,发送端可以不用定义端口
2.定义封装数据包datagrampacket
3.发送数据包
4.关闭资源
 
//InetAddress.getByName("192.168.3.255")必须是统一的网段
 
public class UdpSendThread implements Runnable {

	DatagramSocket ds;
byte[] buf; public UdpSendThread(DatagramSocket ds) {
this.ds = ds;
} public UdpSendThread(DatagramSocket ds, String str) { this.ds = ds;
this.buf = str.getBytes();
} @Override
public void run() { String brStr;
try {
BufferedReader br = new BufferedReader(new InputStreamReader(System.in, "utf-8")); while ((brStr = br.readLine()) != null) { if(brStr.startsWith("@")){ } DatagramPacket dp = new DatagramPacket(brStr.getBytes(), brStr.getBytes().length,
InetAddress.getByName("192.168.3.255"), 9000); ds.send(dp);
if (brStr.equals("over")) {
break;
} } //br.close();
ds.close();
} catch (UnknownHostException | UnsupportedEncodingException e) {
// TODO Auto-generated catch block
e.printStackTrace();
} catch (IOException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}

  

接收端:
1、建立DatagramSocket对象
2、定义一个空的数据包
3、接受数据包
4、解析数据包
5、关闭资源
public class UdpRececiveThread extends Thread {

	DatagramSocket ds;

	public UdpRececiveThread(DatagramSocket ds) {

		this.ds = ds;
} @Override
public void run() { while(true){
byte[] buf = new byte[1024*1024];
DatagramPacket dp = new DatagramPacket(buf, buf.length); try {
ds.receive(dp);
String ip = dp.getAddress().getHostAddress();
String content = new String(dp.getData(),0,dp.getLength());
if(content.equals("over")){
System.out.println(ip+"退出");
} System.out.println(ip+":"+content); } catch (IOException e) {
e.printStackTrace();
} }
}
}

  测试类:

	public static void main(String[] args) throws SocketException {

		DatagramSocket sendDs = new DatagramSocket();
DatagramSocket reDs = new DatagramSocket(9000);
new Thread(new UdpSendThread(sendDs)).start();;
new UdpRececiveThread(reDs).start();
}

  

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