文章地址：[url]http://martinfowler.com/articles/injection.html.[/url] 附件含中文版。

SOFTWARE ENTITIES(CLASSES, MODULES, FUNCTIONS, ETC.) SHOULD BE OPEN FOR EXTENSION, BUT CLOSED FOR MODIFICATION.

原文地址：[url]http://java.dzone.com/articles/visitor-pattern-re-visited[/url] Understanding the problem The actual problem is not the naming and horrible API verbosity of visiting code, but the mis-unde...