java - Receiving unpredictable parameters in Struts2 interceptor -

i aiming write interceptor add headers in response. have following interceptor

public class cachinginterceptor extends abstractinterceptor{      @override     public string intercept(actioninvocation ai) throws exception {         httpservletresponse response = (httpservletresponse) getactioncontext(ai).get(strutsstatics.http_response);         if(null != response) {             response.setheader("cache-control","no-store,no-cache");             response.setheader("pragma","no-cache");             response.setheader("expires","-1");         }         return ai.invoke();     } } 

i need enhance in such way headers can defined in configuration file (struts.xml)

.... <!-- define , add following interceptor in default interceptor stack --> <interceptor name="cachinginterceptor" class="demo.cachinginterceptor"> ....  <action name="myaction" class="demo.myaction">     .... <param name="cache-control">no-store,no-cache</param> <param name="pragma">no-cache</param> <param name="expires">-1</param>     .... </action> 

now have define properties in interceptor class values headers

private string pragma;     //with getter, setter private string expires;    //with getter, setter 

here have 2 problems.

1• cannot define property "cache-control" in java.

2• header names unpredictable, i.e. header can defined in configuration

    <param name="other-header">some-value</param> 

i have 2 questions:

• how can receive header in interceptor defined in struts2 configuration.
• is there better way thing?

with action configuration have defined several static parameters processed via staticparams interceptor. interceptor should proceed first in stack. have retrieve them action context.

map<string, object> params = actioncontext.getcontext().getparameters(); response.setheader("cache-control", ((string[])params.get("cache-control"))[0]); response.setheader("pragma", ((string[])params.get("pragma"))[0]); response.setheader("expires", ((string[])params.get("expires"))[0]);