ActionContextCleanUp的作用

编程技术  /  houtizong 发布于 3年前   77

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 filter
FilterDispatcher
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>