Struts Interceptor Example

<session-config>  
    <session-timeout>30</session-timeout>  
</session-config>			

package cn.netkiller.interceptor;

import java.util.Map;
import java.lang.Override;

import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.interceptor.AbstractInterceptor;

public class SessionInterceptor extends AbstractInterceptor {

	private static final long serialVersionUID = 8347994918002285514L;

	@Override
	public String intercept(ActionInvocation invocation) throws Exception {
		Map<String, Object> session = invocation.getInvocationContext().getSession();
		if (session.isEmpty())
			return "nosession"; // session is empty/expired
		return invocation.invoke();
	}
}			

	<package name="mobile" extends="main" namespace="/mobile">
		<global-results>
			<result name="nosession" type="redirectAction">
				<param name="actionName">Index</param>
				<param name="namespace">/mobile</param>
			</result>
		</global-results>			
		<interceptor name="session" class="cn.netkiller.SessionInterceptor" />
		<interceptor-stack name="sessionExpirayStack">
    		<interceptor-ref name="defaultStack"/>
    		<interceptor-ref name="session"/>
   		</interceptor-stack>
   		<default-interceptor-ref name="sessionExpirayStack" />

		<action name="testAction" class="TestClass">
    		<interceptor-ref name="sessionExpirayStack" />
    		<result name="success">success.jsp</result>
    		<result name="error">error.jsp</result>
  		</action>
  	</package>