[网络协议]7、网络编程之UDP

7、UDP

发短信：不用连接，需要知道对方的地址

发送消息：

//不需要连接服务器
public class UdpClientDemo01 {
    public static void main(String[] args) throws Exception {
        //1.建立一个socket
        DatagramSocket socket = new DatagramSocket();
        //2.建个包
        String msg = "你好啊，服务器！";
        InetAddress localhost = InetAddress.getByName("localhost");
        int port = 9090;
        //数据，数据的长度起始，要发送给谁
        DatagramPacket packet = new DatagramPacket(msg.getBytes(), 0, msg.getBytes().length, localhost, port);

        //3.发送包
        socket.send(packet);
        //4.关闭流
        socket.close();

    }
}

• 接收端：

//还是要等待客户端的连接
public class UdpServerDemo01 {
    public static void main(String[] args) throws Exception {
        //开放端口
        DatagramSocket socket = new DatagramSocket(9090);
        //接收数据包
        byte[] buffer = new byte[1024];
        DatagramPacket packet = new DatagramPacket(buffer, 0, buffer.length);
        socket.receive(packet);//阻塞接收
        System.out.println(packet.getAddress().getHostAddress());
        System.out.println(new String(packet.getData(), 0, packet.getLength()));
        //关闭连接
        socket.close();


    }
}

循环发送消息

public class UdpSenderDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(8888);
        //准备数据：控制台读取 System.in
        BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
        while (true) {
            String data = reader.readLine();
            byte[] datas = data.getBytes();
            DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress("localhost", 6666));

            socket.send(packet);
            if (data.equals("bye")) {
                break;
            }
        }

        socket.close();
    }
}

public class UdpReceiveDemo01 {
    public static void main(String[] args) throws Exception {
        DatagramSocket socket = new DatagramSocket(6666);
        while (true) {
            //准备接收包裹
            byte[] container = new byte[1024];
            DatagramPacket packet = new DatagramPacket(container, 0, container.length);
            socket.receive(packet);//阻塞式接收包裹

            //断开连接，bye
            byte[] data = packet.getData();
            String receiveData = new String(data, 0, data.length);
            System.out.println(receiveData);
            if (receiveData.equals("bye")) {
                break;
            }
        }
        socket.close();
    }
}

在线咨询：两个人都可以是发送方，也都可以是接收方

public class TalkReceive implements Runnable {
    DatagramSocket socket = null;
    private int port;
    private String msgFrom;

    public TalkReceive(int port, String msgFrom) {
        this.port = port;
        this.msgFrom = msgFrom;
        try {
            socket = new DatagramSocket(port);
        } catch (SocketException e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {

        while (true) {
            try {
                //准备接收包裹
                byte[] container = new byte[1024];
                DatagramPacket packet = new DatagramPacket(container, 0, container.length);
                socket.receive(packet);//阻塞式接收包裹

                //断开连接，bye
                byte[] data = packet.getData();
                String receiveData = new String(data, 0, data.length);
                System.out.println(msgFrom + ": " + receiveData);
                if (receiveData.equals("bye")) {
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        socket.close();
    }
}

public class TalkSend implements Runnable {
    DatagramSocket socket = null;
    BufferedReader reader = null;
    private int fromPort;
    private String toIP;
    private int toPort;

    public TalkSend(int fromPort, String toIP, int toPort) {
        this.fromPort = fromPort;
        this.toIP = toIP;
        this.toPort = toPort;
        try {
            socket = new DatagramSocket(fromPort);
            //准备数据：控制台读取 System.in
            reader = new BufferedReader(new InputStreamReader(System.in));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    @Override
    public void run() {


        while (true) {
            try {
                String data = reader.readLine();
                byte[] datas = data.getBytes();
                DatagramPacket packet = new DatagramPacket(datas, 0, datas.length, new InetSocketAddress(this.toIP, this.toPort));

                socket.send(packet);
                if (data.equals("bye")) {
                    break;
                }
            } catch (IOException e) {
                e.printStackTrace();
            }
        }

        socket.close();
    }
}

public class TalkStudent {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend(7777, "localhost", 9999)).start();//new Thread()运用了静态代理模式
        new Thread(new TalkReceive(8888, "老师")).start();
    }
}

public class TalkTeacher {
    public static void main(String[] args) {
        //开启两个线程
        new Thread(new TalkSend(5555, "localhost", 8888)).start();//new Thread()运用了静态代理模式
        new Thread(new TalkReceive(9999, "学生")).start();
    }
}