实现了股票销售者同时与多个顾客之间的信息通信，当一个对象（股票信息）改变状态时，所有依赖者（顾客）都会收到通知并自动更新-To achieve the stock sales were at the same time with multiple customers and information and communication, when an object (stock information) to change the state, all dependent persons (cu