Method A:
ActionContext.getContext().getParameters() (returns Map, works internally using a ThreadLocal)

Method B:
Have the action implements ParameterAware interface and the parameters will be set through the setParameters(Map) method. This requires that the 'servlet-config' interceptor being added to that particular action.

@see webwork-default.xml
@see com.opensymphony.webwork.interceptor.ParameterAware
@see com.opensymphony.webwork.interceptor.Servlet Config Interceptor