这是国外牛人写的一个关于设计模式的观察者的图像化代码，我曾经在设计模式课堂上向老师和同学们演示，获得了很好的评介，值得一看-foreign cattle wrote on the design of a model of the image of the observer code I worked in the design pattern to the classroom teachers and the students demonstration was a good Review, a