I've gotten the basics of Spring more or less down (I think) and I'm trying out new things. Currently, I'm trying to figure out a way not to have explicitly write a service class for each entity/repository if that service is just going to be extending a generic service class.
What I'd like to be able to do is, after the Entity and Repository beans are loaded, loop through them, check to see if a bean named [Model Name]Service exists and, if it does not, create a new instance of my generic service class, pass in the Repository object, and then register this service in the applicationContext.
Is this possible and if so, what is the best way to do it? I've been trying to figure out the PostProcessors, but the one that I think would actual work (BeanPostProcessor) doesn't seem like the appropriate place to do this.
Thanks for your time
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I would like to observe when an entity is saved or deleted so that I may perform additional activities pertaining to that entity. I thought I did this in the past WITHOUT using the #EntityListeners annotation on the entity class itself because my entity listeners would be implemented in the service layer and NOT in the model / data layer.
The only other way I can think of to do it is inside the persistence.xml and specify my listeners there.
Are there any alternate approaches?
I did this a long time ago in a galaxy far, far away, and the answer was in my question.
The solution (that I wanted, but disliked because of using XML) was to:
write a generic entity listener using annotations, and get a programmatic instance of the bean manager (CDI), or equivalent in spring, then fire an event which I can process either via CDI or spring
where I want that listener to work, place a persistence.xml file and manually specify the entity-listeners there
if I want to do anything special, I simply observe the event that I'm interested in and I get the information that I want.
I have a use case, that theoretically seems to me as it would be a solved problem. But i'm not able to find a sure fired implementation.
I've created a RESTful API, using Apache CXF, Spring and Hibernate
This application encompasses a standard Service-Proxy-DAO layered structure
I need to instantiate a custom logger object at my service (or pre-service) layer and initialize a bunch of parameters which will remain constant, for the most part through every call that goes through my application layers and back.
How can i, for every individual service call, initialize this logger object once, and use it across all my layers without having to instantiate it everytime. Either i inject the initialized object in every class i need or something on those lines.
I don't want to use static blocks, or pass the object in method signatures.
Is there anything that i can use as a part of the Spring, CXF or other java framework that allows me to implement this use-case.
EDIT: I would define a transaction as a single call to a web service endpoint, from invocation to response.
ThreadLocal would be an ideal candidate to solve your problem.
UPDATE:
Creating a thread local that is available in all the places where this "shared" reference is required will give all these contexts access to this resource without having to pass the reference around.
see http://www.appneta.com/blog/introduction-to-javas-threadlocal-storage/ - looks like a good explanation of how to use thread local and also deals with your problem space.
I want to share a singleton bean across multiple war. I know sharing ApplicaitonContext using parentContextKey attribute(Example, http://blog.springsource.org/2007/06/11/using-a-shared-parent-application-context-in-a-multi-war-spring-application/)
But this way instance of bean created multiple (for 2 war, 2 instance). I want only 1 instance across 2 war.
Another way, If i set some value in any POJO, it should be accessible in another war.
Reason i need this is, there are some beans(like HibernateSessionFactory, Datasource etc which are expensive) which are created multiple times(n instance for n war). Whereas i want to utilize same instance instead of creating same in different war.
Can anyone provide me solution for this?
You could achieve this by binding the objects into the global JNDI tree. That means that both WARs would have references to an object looked up in JNDI.
Hibernate allows you to use the hibernate.session_factory_name property (this may well be a good starting point. Data sources should already be looked up from JNDI.
One thing, I would not class a session factory or a data source as expensive, so you may well be saving a miniscule amount of memory in exchange for a lot of additional complexity, so I would ask myself the question on whether this is worth the additional maintenance headaches.
Spring provide a way to expose any bean (service) and these bean can be access from any other web application or any standalone application.
please refer Remoting and Web Service using Spring to get more details.
Say I have a file with each line depicting a different command (but of the same kind), which I want to read out and check and run and maybe do other operations such as merging, comparing and most importantly, store the commands into database.
To do that, I create the Command Class, and new a new Command object while reading each line of the file. Now the problem is, a Command object need to make use of, say a Spring bean which provides database access. As a result, I have to pass in that bean as a constructor argument of the Command class, which is very ugly, which doesn't seem to be the "Spring way"...
and I don't want to use ApplicationContextAware to make my class coupled to the Spring context.
Is there a best practice for this situation?
I very new to Spring and I know it might be a dumb question ...
I would create a CommandFactory that is coupled with spring and use that in your consumer instead. If the factory implements an interface you are not coupling yourself in the consumer and you don't close your possibilities of using a different -non spring coupled- one at a later point (e.g. testing).
In this case I think it is the best way to make the classes created by new Spring Beans.
Therefor annotate them with #Configurable, enable AspectJ, and read the Spring Reference Chapter 7.8.1 Using AspectJ to dependency inject domain objects with Spring
is it possible to inject a service reference into custom type converter?
my situation is quite typical in fact, I have a combo, which binds to collection of entities. On submit I get only an ID of selected entity and have to refetch the real object in my action. I was thinking about more elegant way to do this, and it seems like making an ID-to-entity custom converter which would perform fetching - would be a good idea.
But I failed trying to map a converter to Spring bean in the same fashion like actions...
Interesting question. Are you using the spring plugin ?.
It is supposed to take care of service-objects creation, (and wiring with other services) for Struts2, and this should be able to include Type Converters. From here:
By using the struts2-spring-plugin in conjunction with type conversion, developers easily can use dependency injection to provide a converter with services
But I have not used that feature.