设计模式（Design pattern）代表了最佳的实践，通常被有经验的面向对象的软件开发人员所采用。设计模式是软件开发人员在软件开发过程中面临的一般问题的解决方案。这些解决方案是众多软件开发人员经过相当长的一段时间的试验和错误总结出来的。(Consider the work of a future software archeologist, tracing the history of
computing. The fossil record will likely show clear strata: here is a layer
formed of assembly language artifacts, there is a layer populated with the
skeletons of high order programming languages (with certain calcified legacy
parts probably still showing some signs of life). Each such layer will be
intersected with the imprint of other factors that have shaped the software
landscape: components, residue from the great operating system and)