I have a number of classes that I have implemented as Features
(javax.ws.rs.core.Feature), in order to have a singleton instance of
them availabe within my application.
For example:
public class AgentSessionCacheFeature implements Feature {
@Override
public boolean configure(final FeatureContext context) {
context.register(new AgentSessionCacheBinder());
return true;
}
}
The corresponding Binder instantiates the class:
public class AgentSessionCacheBinder extends AbstractBinder {
@Override
protected void configure() {
bind(new AgentSessionCache()).to(AgentSessionCache.class);
}
}
I register the Feature in my Application as follows:
@ApplicationPath("/*")
public class MyApplication extends ResourceConfig {
public MyApplication() {
register(AgentSessionCacheFeature.class);
This all works fine: the singleton instance is created, and I use it
throughout my application.
My question is: how can I get a hook to tell this instance when Tomcat
is shutting down, so that it can release resources?
I have created a class that implements ServletContextListener, and in
that class I override the contextDestroyed method.
@WebListener
public class MyAppServletContextListener implements ServletContextListener {
private final Logger logger =
LoggerFactory.getLogger(MyAppServletContextListener.class);
@Inject
private AgentSessionCache agentSessionCache;
@Override
public void contextDestroyed(ServletContextEvent sce) {
if (agentSessionCache != null) {
agentSessionCache.shutdown();
} else {
logger.warn("MyAppServletContextListener.contextDestroyed:
agentSessionCache == null.");
}
}
}
However, when contextDestroyed is called, my singleton instance is null.
So perhaps it has already been destroyed separately by HK2 before
contextDestroyed is called? Or perhaps HK2 is not able to inject it into
my ServletContextListener?
In any case, my goal is to find a hook I can use to release resources
from singleton classes I instantiate via the Feature/Binder strategy.