I have tried to use struts 1.3 API to make a small application with EJB 3.0. Unfortunatelly i cannot use the #EJB annotation to call my bean object from inside my action class. I have solved this problem using different workarounds ( the first one is to use my global jndi name of my bean and the other is to call another class first and use the #EJB annotation from that class). Still these two workarounds have significant disadvantages. I would like to call my EJB directly from my action class. I have read plenty examples using the "java:comp/env/beanName" JNDI name but still haven't figure out how to do it and get name not found axception.
Let the full name of the local EJB class be the com.ejb.myEjbPackage.MyEJBLocal, how can i call it using the context lookup? (can i do it without modifying any of the web.xml and sun-web.xml descriptors?)
I am using glassfish server and Netbeans IDE.
Thank you in advance
#EJB won't work in a standard pojo it can only be done in a managed object (i.e. another session bean)
So...
Here's your bean
#Stateless(mappedName="beanName")
public class beanName implements beanNameRemote {
Here's your lookup
Context context = new InitialContext(); //default lookup pulls from jndi properties file
context.lookup("beanName");
You can do some further reading on the mappedName to see if you want to use it or not.
I found the answer :
If you cannot use the EJB annotation in the class you want to call the bean then :
If you don't want to mess with XML descriptors to define your bean , you have to do it in the bean class itself.
Hence i used the following annotation in the GameBean class
#Stateless
#EJB(name="ejb/GameBean",beanInterface=GameBeanLocal.class,beanName="GameBean")
public class GameBean implements GameBeanLocal {.....
The beanName is optional. The annotation must be declared in the line ABOVE the declaration of the class.
Then, in order to call the bean from the other class you can do
InitialContext ic = new InitialContext();
ic.lookup("java:comp/env/ejb/GameBean");
Related
I have a service that needs to use Neo4jRepository (regular repository provider by spring data).
public class SomeServiceBean<T>{
#Autowired
private Neo4jRepository<T,Long> Neo4jRepository;
}
This class will generate en error:
expected single matching bean but found 2: systemUserRepository,systemClaimRepository
The problem is that systemClaimRepository and systemUserRepository is extending Neo4jRepository<T,Long> as a bean without implementation.
Spring see systemClaimRepository and systemUserRepository as Neo4jRepository<T,Long> because they are extending it.
Is there anyway to inject Neo4jRepository<T,Long>?
Thanks
No how should this work?
You have two beans that match the interface and Spring does not know which implementation to inject.
I have a JAX-RS web service that was generated by Netbeans. There are non-abstract facade classes for the service's endpoints. The persistence context is being injected into the non-abstract facade. Everything is working well and I see my data being returned to Fiddler.
We are using DTOs and I am implementing an assembler pattern. So, in the non-abstract facade's constructor, I am creating an instance of the assembler, and am passing the facade's entity manager instance into it. Unfortunately, it seems that the injection of the persistence context has not happened before the facade's constructor has been called, so I cannot pass the entity manager instance into the assembler for its to use in mapping operations. Kind of a chicken-before-the-end situation... I cannot figure out how to make this work... Is there some kind of post-constructor method that I can override and perform the initialization of the assembler and pass in the entity manager to it? I'd really appreciate your help and suggestions.
Thank you for your time and ideas,
Mike
Use method marked with #PostConstruct annotation. Like this:
#PostConstruct
private void init() {
// I'm called after all injections have been resolved
// initialize some object variables here
...
}
In that method you can use both, object fields initialized in the constructor and passed by injection.
Until to now i use (like beginner) JSF. Usually I make xhtml page and backend bean. And in backing bean I use annotation like #ManagedBean, #SessionScoped, #Application and so on. i think that is annotation for javax.faces.bean, if it is correctly that is faces annotations.
Bath I find one tutorial on internet where one guy use annotation like #Model an most interesting in backand bean He uses the #Inject annotation. I find that is very useful. He use injection for Logger class and in same bean can use methods from that class. Something like these:
#Model
public class FileUploadBean {
#Inject Logger log;
private Part file;
public void upload(){
...
}
}
Are there he use enterprise java, maybe CDI and how I can use this annotation. Because when i write #Inject in my Backing bean have message that is ambiguous annotation.
What i have to know and about what?
I working with eclipse and glassfish!
You're talking about the javax.enterprise.Inject annotation. See the cdi tag wiki page for some basic information. The only thing you'd need to have is the corresponding import statement.
A word of warning: if you already have a project with JSF beans, note that most scope annotations (#SessionScoped, #RequestScoped, ...) have a CDI equivalent that has the same name. Make sure you import the correct annotation or you'll find that your "session bean" suddenly has only request scope.
See also:
Weld Reference
JEE6 CDI Tutorial
I have several services deployed as EJBs on a JBoss-AS-7.1 server. Many applications use these EJBs by doing a lookup like this:
#EJB(lookup = "java:global/FooService/FooBean!com.xyz.FooBeanRemote")
private FooBeanRemote fooBeanRemote;
The problem is that the lookup string is hard-coded in the source. I want to be able to change this lookup at runtime - without a re-compilation - because FooService may be updated some time in the future, and perhaps have a different implementation. In addition, the ejb could also move to a different server instance.
What would be the best way to achieve this?
Use ejb-jar.xml instead of annotation (check here)
use InitialContext in your code to lookup for bean and move bean name to properties file
Implement CDI producer methods in separate jar
--EDIT---
Quick HOWTO about last point:
1. Create qualifier
#Qualifier
#Retention(RUNTIME)
#Target({FIELD, TYPE, METHOD})
public #interface FooService {
}
2. Create producer method
public class EJBProducer {
#Produces
#FooService
#EJB(lookup = "java:global/FooService/FooBean!com.xyz.FooBeanRemote")
private FooBeanRemote fooBeanRemote;
}
3. Use in your code
#Inject #FooService
private FooBeanRemote fooBeanRemote;
Two first points may be in another jar archive (remember to include there META-INF/beans.xml file). You can also use producer method instead of field, and access ejb programmatically.
I have a method on a stateless session bean which creates a new instance of an entity and persists it. You might normally use new MyEntity() to create the object but I would like injection to populate some of the properties of the entity for me.
I got partial success using
#Inject
#New
private MyEntity myNewEntity;
in the session bean and then using that instance in my method.
The problem I have now is that the second time the method is called, myNewEntity isn't a new object, its the same object as the one created the first time. As a result I'm getting
com.mysql.jdbc.exceptions.jdbc4.MySQLIntegrityConstraintViolationException: Duplicate entry '9' for key 'PRIMARY'
Or at least that's why I think I'm getting this exception. Certainly if I use new MyEntity() I don't get the exception but my injection doesn't happen.
Am I on the wrong track? How can I create a new local entity object while enabling injection?
Any help would be great!
First of all - I have serious doubts that it's a good idea to use CDI to control the lifecycle of a Entity. See this quote from the documentation (here):
According to this definition, JPA
entities are technically managed
beans. However, entities have their
own special lifecycle, state and
identity model and are usually
instantiated by JPA or using new.
Therefore we don't recommend directly
injecting an entity class. We
especially recommend against assigning
a scope other than #Dependent to an
entity class, since JPA is not able to
persist injected CDI proxies.
What you should do to create new instances of entities is adding a layer of indirection, either with #Produces or #Unwraps (Seam Solder, if you need it to be truly stateless), and thereby making sure that you code explicitly calls new.
I think I have a working solution now which seems okay, though I'm not quite sure why it works so I welcome your feedback on a better solution. I am now injecting a DAO-style bean into my stateless session bean:
#Stateless
public class PhoneService {
#Inject
protected ProblemReports problemReports;
An injecting my entity into the ProblemReports bean:
public class ProblemReports {
#Inject
#New
private ProblemReport newProblemReport;
I assume that ProblemReports defaults to #Dependant scope which as I understand it should be the same as the stateless session bean which containts it. I could understand this if the scope of ProblemReports was shorter, causing a new instance of ProblemReport to be created when the new ProblemReports is created; but it isn't.
Is this just an example of EJB and CDI not playing well together?