一个小型计算器，实现了数值的加、减、乘、除运算。-A small calculator, the realization of the value add, subtract, multiply, with the exception of computing.

proxool连接池可以实时监测连接情况，内部的jar包已经手动修改过，可以再控制台正确的显示，不会因乱码问题而抛异常-proxool connection pool can be a real-time monitoring of connections inside the jar package has been manually modified, can console display, not the garbage problem and throw exception

关于mysql5.7json类型查询异常问题。。。。(On the mysql5.7json type query exception problem)