UDP收发消息

udp协议使用数据报套接字，无需建立链接

//send
public class Udp_Send_01 {
	public static void main(String[] args) throws IOException {
		
		DatagramSocket socket=new DatagramSocket();
		
		InetAddress add=InetAddress.getByName("localhost");
		int port=9090;
		String msg="你好啊";
		DatagramPacket data=new DatagramPacket(msg.getBytes(), 0,msg.getBytes().length,add,port);
		
		socket.send(data);
		
		socket.close();
		
	}
}
//receive
public class Udp_Receiver_01 {
	public static void main(String[] args) throws IOException {
		DatagramSocket socket=new DatagramSocket(9090);
		
		byte[] bytes=new byte[1024];
		DatagramPacket packet=new DatagramPacket(bytes, 0,bytes.length);
		socket.receive(packet);//阻塞接收
		System.out.println(packet.getAddress());
		System.out.println(new String(packet.getData(),0,packet.getData().length));
		
		socket.close();
		
	}
}
/*************************循环发送，接收*************************/
public class Sender_01 {
	public static void main(String[] args) throws IOException {
		DatagramSocket socket=new DatagramSocket(8888);
	
		BufferedReader reader=new BufferedReader(new InputStreamReader(System.in));
		
		String data;
		byte[] bytes;
		
		while(!(data=reader.readLine()).equals("bye")) {
			
			bytes=data.getBytes();
			DatagramPacket pack=new DatagramPacket(bytes,0,bytes.length,new InetSocketAddress("localhost", 6666));
			socket.send(pack);
		}
		socket.close();

	}
}
//
public class Receiver_01 {
	public static void main(String[] args) throws IOException {
		DatagramSocket socket=new DatagramSocket(6666);
		
		byte[] bytes=new byte[1024];
		DatagramPacket packet=new DatagramPacket(bytes, 0,bytes.length);
		while(true) {
			socket.receive(packet);
			String msg=new String(packet.getData(),0,packet.getData().length);
			if(msg.equals("bye")) {
				break;
			}
			System.out.println(msg);
			
		}
		socket.close();
	
	}
}

建立一个通用收发线程实现全双工收发

//发送消息线程
public class Sendmsg implements Runnable{
	DatagramSocket socket=null;
	BufferedReader reader=null;
	private int fromport;
	private String toip;
	private int toport;
	private String name;
	public Sendmsg(int fromport,String toip,int toport,String name) throws SocketException, UnknownHostException {
		// TODO Auto-generated constructor stub
		this.fromport=fromport;
		this.toip=toip;
		this.toport=toport;
		this.name=name;
		
		socket=new DatagramSocket(this.fromport);
		reader=new BufferedReader(new InputStreamReader(System.in));
		
	}
	@Override
	public void run() {
		// TODO Auto-generated method stub
		String data;
		byte[] bytes;
		
		try {
			
			while(!(data=reader.readLine()).equals("bye")) {
				
				bytes=(name+":"+data).getBytes();
				DatagramPacket pack=new DatagramPacket(bytes,0,bytes.length,new InetSocketAddress(this.toip, this.toport));
				socket.send(pack);
			}
			
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		try {
			reader.close();
		} catch (IOException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		socket.close();
	}

}
//接收消息线程
public class Receivemsg implements Runnable{

	DatagramSocket socket=null;
	private int port;//从此端口接收消息
	public Receivemsg(int port) throws SocketException {
		// TODO Auto-generated constructor stub
		this.port=port;
		socket=new DatagramSocket(this.port);
	}
	@Override
	public void run() {
		// TODO Auto-generated method stub
		
		byte[] bytes=new byte[1024];
		DatagramPacket packet=new DatagramPacket(bytes, 0,bytes.length);
		while(true) {
			try {
				socket.receive(packet);
			} catch (IOException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
			}
			String msg=new String(packet.getData(),0,packet.getData().length);
			if(msg.equals("bye")) {
				break;
			}
			System.out.println("address:"+packet.getAddress()+" "+msg);
			
		}
		socket.close();
	}

}
//新建两个类的收发线程
public class Student {
	public static void main(String[] args) throws SocketException, UnknownHostException {
		new Thread(new Sendmsg(6666, "localhost", 8888, "student")).start();
		new Thread(new Receivemsg(7777)).start();
	}
}
public class Teacher {
	public static void main(String[] args) throws SocketException, UnknownHostException {
		new Thread(new Sendmsg(5555, "localhost", 7777, "teacher")).start();
		new Thread(new Receivemsg(8888)).start();
	}
}