本文主要是为了给大家一份能在短时间内学习好Java的资料，希望大家能通过这21天的学习，能很快的了解java的一些基础知识，为以后能做项目打下基础。-This article is aimed to give you a can in a short period of time learning Java data well, hope you can pass this 21 days learning, can quickly learn some basic knowledge of Java, project lays the foundation for later can do.