说明：  现两台计算机相互通讯数据，需掌握一种编程接口并使用一种编程模型，这就是网络编程。Java SDK提供一些相对简单的Api来完成这些工作。Socket就是其中之一，对于Java而言，这些Api存在与java.net 这个包里面，因此只要导入这个包就可以准备网络编程了。
(Are two computers communicate with each other data required to master a programming interface and uses a programming model, which is network programming. Java SDK to provide some relatively simple Api to complete these tasks. Socket is one of them, for Java, these Api exist inside the bag with the java.net, so as long as the import of this package can be a ready network programming.)