摘要：
观察者模式定义：Define a one-to-many dependency between objects so that when one object changes state, all its dependents aer notified and updated automatically.定义对象间一种一对多的依赖关系，使得当一个对象改变状态，则所有依赖于它的对象都会得到通知并被自动更新。 如上图所示 阅读全文
观察者模式定义：Define a one-to-many dependency between objects so that when one object changes state, all its dependents aer notified and updated automatically.定义对象间一种一对多的依赖关系，使得当一个对象改变状态，则所有依赖于它的对象都会得到通知并被自动更新。 如上图所示 阅读全文