telnet 使用

telnet time-a.nist.gov 13

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java 使用Socket连接到服务器

使用inputStream进行处理

public static void getInfoUseInputStream(String url, int port) {
        try (Socket s = new Socket(url, port)) {
            InputStream inputStream = s.getInputStream();
            //对网络传来的输入流进行读取
            //如果这里不先进行读取则获取不到
            int firstByte = inputStream.read();
            int available = inputStream.available();
            while (available > 0) {
                byte[] bytes = new byte[available + 1];
                bytes[0] = (byte) firstByte;
                inputStream.read(bytes, 1, available);
                System.out.println(new String(bytes));
                available = inputStream.available();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

使用Scanner进行处理 :逐段扫描文本

    public static void getInfoUseScanner(String url, int port) {
        try (Socket socket = new Socket(url, port);
             Scanner in = new Scanner(socket.getInputStream(), "UTF-8")) {
            while (in.hasNextLine()) {
                String line = in.nextLine();
                System.out.print(line);
            }
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

打印出hostname对应的ip

public static void main(String[] args) throws UnknownHostException {
        if(args.length>0){
            String host =args[0];
            try {
                InetAddress[] addresses=InetAddress.getAllByName(host);
                for(InetAddress a:addresses){
                    System.out.println(new String(a.getAddress()));
                }
            } catch (UnknownHostException e) {
                e.printStackTrace();
            }
        }else {
            InetAddress localHostAddress=InetAddress.getLocalHost();
            byte[] address = localHostAddress.getAddress();
            // byte值为 -64,-88,0,-127,
            for(int a=0;a<address.length;a++){
                System.out.print((0xff&address[a])+(a!=address.length-1?".":""));
            }
            //直接打印ip
            System.out.print("\n"+localHostAddress.getHostAddress());
        }
    }

结果

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