Question

I have a Spring MVC web app which uses FreeMarker for rendering the views and have come up with the following issue.

Within my FreeMarker config I declare a Singleton Spring bean as a FreeMarker variable and within my application I have provided the mechanism for the Singleton Bean to be dynamically refreshed (the bean contains the application config retrieved from the DB).

Now the problem is that when it is refreshed the previously rendered FreeMarker templates use the values within the older version yet if I navigate to a page not rendered since the container started it uses the new values.

The following is a snippet of my FreeMarker config:

<!-- FreeMarker config -->

<bean id="freemarkerViewConfig" class="org.springframework.web.servlet.view.freemarker.FreeMarkerConfigurer">
    <property name="templateLoaderPaths">
        <array>
            <value>/WEB-INF/freemarker</value>
            <value>classpath:/WEB-INF/freemarker</value>
        </array>
    </property>
    <property name="freemarkerSettings">
        <props>
            <prop key="datetime_format">dd/MM/yyyy</prop>
            <prop key="number_format">#</prop>
            <prop key="whitespace_stripping">true</prop>
            <prop key="auto_import">
                spring.ftl as spring,
                custom-macros.ftl as custom,
            </prop>
        </props>
    </property>
    <property name="freemarkerVariables">
        <map>
            <entry key="xml_escape" value-ref="fmXmlEscape"/>
            <entry key="html_escape" value-ref="fmHtmlEscape"/>
            <entry key="config" value-ref="config"/>
        </map>
    </property>
</bean>

To refresh the config model I execute the following within my Controller class:

((XmlWebApplicationContext)applicationContext).refresh();

Having this configuration picks up the refreshed config model when accessing a page which hasn’t been already rendered but won’t recognise the change on pages already visited.

I have tried the following to enforce the ‘refresh’ of the variable with no luck:

1. In the controller after the context is refresh I clear the templateCache within the FreeMarker Config which has been autowired:

   freeMarkerConfig.getConfiguration().clearTemplateCache();

2. I have also tried disabling the caching of templates within the FreeMarker config using the following property within freeMarkerSettings:

   freemarker.cache.NullCacheStorage

Finally, its worth pointing out that when in debug and looking through the cache and configuration the Shared Variable does indeed reference the most up to date config model yet the page renders using the older version.

Any advice / guidance on how to resolve this?

ps I am using Spring v3.1.1.RELEASE and FreeMarker v2.3.19

Answer 1

Not quite a solution but I have fixed my issue but it is more a hack to be honest.

I changed the code to refresh my config by using the following command so only the config bean was recreated:

((DefaultListableBeanFactory) beanFactory).destroySingleton("config");

And then modified the freemarker config by removing the reference to the config model as regardless what I tried I could not get this to be refreshed. So the solution to my issues was then to modify the BaseController which every controller within the application extends exposing the config model available as a @ModelAttribute so it was available to all the views.

As I said doesn’t really solve the underlying issue but I have solved my problem albeit in a unorthodox fashion.