责任链的一个小例子：责任链模式是一种对象的行为模式， 在责任链模式里，很多对象由每一个对象对其下家的引用而连接起来形成一条链。-A small example of the chain of responsibility: Chain of Responsibility pattern is a pattern of behavior objects in the chain of responsibility pattern, many objects from each object reference to its connection under the house to form a chain.