I am trying set a init-param for struts 2 filter like this:
<init-param>
<param-name>config</param-name>
<param-value>struts-default.xml,struts-plugin.xml,/WEB-INF/etc/struts.xml</param-value>
</init-param>
but it does't work. Can't we put struts 2 configuration file outside class path?
No, you can't, but you can specify a relative path
<param-value>struts-default.xml,struts-plugin.xml,../etc/struts.xml</param-value>