延长action中属性的生命周期，包括自定义属性，以便在jsp页面中进行访问，让actionContextcleanup过滤器来清除属性，不让action自己清除。
为了使用WebWork,我们只需要在web.xml配置FilterDispatcher一个过滤器即可,阅读一下FilterDispatcher的JavaDoc和源码,我们可以看到它调用了:
finally
{ ActionContextCleanUp.cleanUp(req);}在ActionContextCleanUp中,有这样的代码:
req.setAttribute(CLEANUP_PRESENT, Boolean.TRUE);
如果FilterDispatcher检测到这个属性,就不会清除ActionContext中的内容了,而由ActionContextCleanUp后续的代码来清除,保证了一系列的Filter访问正确的ActionContext.
文档中提到,如果用到SiteMesh的Filter或者其他类似Filter,那么设置顺序是:
ActionContextCleanUp filter
SiteMesh filterFilterDispatcher所以最后我们的web.xml应该类似这样:<filter>
<filter-name>ActionContextCleanUp</filter-name><filter-class>com.opensymphony.webwork.dispatcher.ActionContextCleanUp</filter-class></filter><filter>
<filter-name>sitemesh</filter-name><filter-class>com.opensymphony.webwork.sitemesh.FreeMarkerPageFilter</filter-class></filter><filter>
<filter-name>webwork</filter-name><filter-class>com.opensymphony.webwork.dispatcher.FilterDispatcher</filter-class></filter><filter-mapping>
<filter-name>ActionContextCleanUp</filter-name><url-pattern>/*</url-pattern></filter-mapping><filter-mapping>
<filter-name>sitemesh</filter-name><url-pattern>/*</url-pattern></filter-mapping><filter-mapping>
<filter-name>webwork</filter-name><url-pattern>/*</url-pattern></filter-mapping>