网络通讯的三要素

IP地址

public class dome {
    public static void main(String[] args)  {
        try {
            //获取本机IP地址对象
            InetAddress localHost = InetAddress.getLocalHost();
            //获取本机名
            System.out.println(localHost.getHostName());
            //获取本机地址名
            System.out.println(localHost.getHostAddress());

            //获取指定IP或局域网的IP地址对象
            InetAddress inetAddress = InetAddress.getByName("www.baidu.com");
            System.out.println(inetAddress.getHostName());
            System.out.println(inetAddress.getHostAddress());

            //判断本机和与该ip地址是否连通
            System.out.println(inetAddress.isReachable(2000));
        } catch (UnknownHostException e) {
            System.out.println(e.getLocalizedMessage());
        } catch (IOException e) {
            System.out.println(e.getLocalizedMessage());
        }
    }