Spring how to execute method

Question

I know this question is a duplicate of Execute method on startup in spring. however I have tried the advice posted in the accepted answer for that question, and nothing has worked for me. As such, I suspect that although it is the same question being asked here, I strongly feel that the root cause is different and thus requires a different answer/solution.

I am trying to get Spring to create a bean at start up and immediately execute one of its methods.

My spring config (heartbeat-config.xml):

<beans (all the xmlns stuff here ommitted for brevity)>
    <bean id="heartbeat" class="org.me.heartbeat.Heartbeat"/>
</beans>

And Heartbeat.java:

public class Heartbeat
{
    @PostConstruct
    public void start()
    {
        System.out.println("I should see this message in the logs somewhere!!");
    }
}

And finally, my web.xml:

<?xml version="1.0" encoding="UTF-8"?>
<web-app
    xmlns="http://java.sun.com/xml/ns/j2ee"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd"
    version="2.4">

    <!-- The display name of this web application -->
    <display-name>Heartbeat</display-name>

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/heartbeat-config.xml</param-value>
    </context-param>

    <listener>
        <listener-class>
            org.springframework.web.context.ContextLoaderListener
        </listener-class>
    </listener>
</web-app>

When I run this in Tomcat I don't get any startup errors. Tomcat looks like its running healthy (as I can tell from the logs). I do not, however, see any output in the logs that should be generated by the System.out invocation in my start() method (Tomcat redirects all standard output to its log files).

Am I overlooking something here? Is there an obvious diagnosis I could be performing?

You need to tell us what happened when you tried the solution from the other question, else we don't know how to answer differently, and this would still be a duplicate. — skaffman, Feb 07 '12 at 20:32
Ahhh, the only change I made from the other question was adding the `@PostConstruct` annotation. Same results either way, hence the solution did not work for me whereas it did work for the other asker. — IAmYourFaja, Feb 07 '12 at 20:39
flurdy what would my other options be? Can you post an example? Thanks! — IAmYourFaja, Feb 07 '12 at 20:40
Not sure it's the solution, but the API doc of ContextLoader uses `WEB-INF/applicationContext.xml`, and not `/WEB-INF/applicationContext.xml`. No leading slash. Could you put some debugging in the Heartbeat constructor to see if it's instantiated or not (or even start tomcat in debug mode). — JB Nizet, Feb 07 '12 at 20:41
Good suggestioned JB Nizet! Now we're getting somewhere. I put an output statement in the (added) constructor and saw it show up in the logs. I did not have to remove that leading slash (and actually, this web.xml is a near-clone of another one used in a perfectly-functioning WAR, so I know thats not the issue). Any ideas as to why I can instantiate the bean but not call its `start()` method?!?! — IAmYourFaja, Feb 07 '12 at 20:47
HRigger - where would I place that context element? Under the `` element or inside my Heartbeat bean? — IAmYourFaja, Feb 07 '12 at 20:48

score 4 · Accepted Answer · answered Feb 07 '12 at 20:43

The most simple way to do that is to forget about annotations and change your bean definition to:

<bean id="heartbeat" class="org.me.heartbeat.Heartbeat" init-method="start"/>

If you want annotations you need to declare the context namespace and put this int your applicationContext.xml:

<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="
       http://www.springframework.org/schema/beans
       http://www.springframework.org/schema/beans/spring-beans.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context-2.5.xsd">

    <!-- Enable @PostConstruct, @PreDestroy and friends in Spring -->
    <context:annotation-config/>

    <bean id="heartbeat" class="org.me.heartbeat.Heartbeat"/>
</beans>

Note: check the namespaces, they are copypasted from the net.

Spring how to execute method

1 Answers1