dwr 的session异常

<!--dwr config-->
	<servlet>
	    <servlet-name>dwr-invoker</servlet-name>
	    <servlet-class>org.directwebremoting.servlet.DwrServlet</servlet-class>
	    <init-param>
	      	<param-name>debug</param-name>
	      	<param-value>true</param-value>
	    </init-param>
	    <init-param>
	      	<param-name>activeReverseAjaxEnabled</param-name>
	      	<param-value>true</param-value>
	    </init-param>
	    <init-param>
	      	<param-name>initApplicationScopeCreatorsAtStartup</param-name>
	      	<param-value>true</param-value>
	    </init-param>
	    <init-param>
	      	<param-name>maxWaitAfterWrite</param-name>
	      	<param-value>100</param-value>
	    </init-param>
	    <init-param>
	    	<param-name>crossDomainSessionSecurity</param-name>
	    	<param-value>false</param-value>
	    </init-param>
	    <load-on-startup>-1</load-on-startup>
   </servlet>
	
    <servlet-mapping>
      <servlet-name>dwr-invoker</servlet-name>
      <url-pattern>/dwr/*</url-pattern>
    </servlet-mapping>
	<!--dwr end -->