Creating Spring Service that reads a file and serve queries based on its data - spring

Question

In a Java Web Project with Spring and JSF, I want do this: I want to have a service that in the first run of the app, reads a file and puts its data to a variable. then other classes can read that variable.
In fact I want that file reads one time and after that I just query the data, even web pages changed via links and navigation system.
Is there a Spring annotation to turn class to a service like this? Should I have some XML config files to specify a class as a service? I don't know what I have to do. What I know is that it can be done via Spring and I can get its data from JSF components, but how?
I have to do this based on MVC.

Answer 1

You can have it lazy-loaded on first call of the service. Or you can add a ContextListener to initialize the service on startup of the web context, assuming you are deploying to a J2EE container. Or you can make that service a spring bean with an init-method that initializes the data. Or any one of a hundred different ways. You'll need to determine what works best for your application.
Here's a spring example:
<beans xmlns="http://www.springframework.org/schema/beans"
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-2.5.xsd">
<bean id="myService"
class="org.your.Service"
init-method="initializeData"></bean>
</beans>
How you get hold of that service is up to you. You can either have the data stored statically on the class, or you can use the spring context to retrieve this single instance of the spring bean.
Spring documentation for lifecycle methods: http://docs.spring.io/spring/docs/current/spring-framework-reference/htmlsingle/#beans-factory-lifecycle