??? ?? ??? ????? ??? ???? ??????? ???? ???? ????? ????? ?? ??? ????? ??? ???? ??????? ???? ???? ????? ?? 紧耦合的类很难独立的被复用因为他们是相互依赖的 松散耦合提高了一个类本身被复用的可能性并且系统更易于学习移植修改和扩展 Someone has already solved y