UDP协议

发送数据：

public class SendMessageDemo {
    static void main() throws IOException {
        //发送数据

        //1.创建DatagramSocket对象(快递公司)
        //细节:绑定对应的端口
        //空参:所有可用的端口随机一个进行使用
        //有参:指定端口号进行绑定
        DatagramSocket ds = new DatagramSocket();
        //2.打包数据
        String str = "你好维阿";
        byte[] bytes = str.getBytes();
        InetAddress address = InetAddress.getByName("127.0.0.1");
        int port = 10086;
        DatagramPacket dp = new DatagramPacket(bytes,bytes.length,address,port);
        //3.发送数据
        ds.send(dp);
        //4.释放资源
        ds.close();
    }
}

接受数据：

public class ReceiveMessageDemo {
    static void main() throws IOException {
        //接收数据
        //1.创建DatagramSocket对象(快递公司)
        //细节
        //接收时一定要绑定端口
        //端口要和发送的端口保持一致
        DatagramSocket ds = new DatagramSocket(10086);

        //2.接受数据包
        byte[] bytes = new byte[1024];
        DatagramPacket dp = new DatagramPacket(bytes,bytes.length);
        ds.receive(dp);

        //3.接受数据包
        byte[] data = dp.getData();
        int len = dp.getLength();
        InetAddress address = dp.getAddress();
        int port = dp.getPort();
        System.out.println("接收到数据"+new String(data,0,len));
        System.out.println("该数据是从"+address+"这台电脑中的"+port+"这个端口发出的");


    }
}