中介者模式: 用一个中介对象来封装一系列的对象交互。中介者使各对象不需要显式地相互引用，从而使其耦合松散，而且可以独立地改变它们之间的交互。-Intermediary model: using an intermediary object to encapsulate the set of objects interact. Intermediaries to make objects do not need to explicitly refer to each other, making i