next() 针对不带空格的字符串

 public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        System.out.print("地址：");
        String host = s.next();
        System.out.println("host = " + host);
        System.out.print("端口：");
        String port = s.next();
        System.out.println("port = " + port);
        System.out.print("用户名：");
        String user = s.next();
        System.out.println("user = " + user);
        System.out.print("带空格的用户名：");
        String userSpace = s.next();
        System.out.println("userSpace = " + userSpace);
    }

nextLine()针对带空格的字符串

  public static void main(String[] args) {
        Scanner s = new Scanner(System.in);
        System.out.print("地址：");
        String host = s.nextLine();
        System.out.println("host = " + host);
        System.out.print("端口：");
        String port = s.nextLine();
        System.out.println("port = " + port);
        System.out.print("用户名：");
        String user = s.nextLine();
        System.out.println("user = " + user);
        System.out.print("带空格的用户名：");
        String userSpace = s.nextLine();
        System.out.println("userSpace = " + userSpace);
    }