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 redundant code, so very suitable for beginners to learn.