这是一个典型的使用java.net包的类来做的端口扫描程序，展示了最常用的类的用法。因为它简单，没有任何多余冗长的代码，所以非常适合初学者学习。-This is a typical class using java.net package to do the port scanning procedures, demonstrated the most commonly used type of usage. Since it is easy, there is no lengthy redun