Java 网络编程（六）UDP

UDP

发短信：不用连接，需要知道对方的地址

客户端：

//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！";
        //发送给谁
        InetAddress localhost = InetAddress.getByName("localhost");
        int port = 9090;
        DatagramPacket datagramPacket = new DatagramPacket(msg.getBytes(),0,msg.getBytes().length,localhost,port);
        //3.发送包
        socket.send(datagramPacket);
        //4.关闭流
        socket.close();
    }
}

接收端：

//还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
        byte[] buffer = new byte[1024];
        DatagramPacket datagramPacket = new DatagramPacket(buffer, 0, buffer.length);
        socket.receive(datagramPacket);//阻塞接受
        System.out.println(datagramPacket.getAddress().getHostAddress());
        //关闭连接
        socket.close();
    }
}

循环接收消息：

发送方：

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();
    }
}

接收方：

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