First of all I want to say I'm pretty new in programming with ejb and jsf, and I'm trying to complete a project started by a friend of mine.
I'm getting a NullPointerException caused by the invoke of the method utenteSessionBean.CheckUtentebyId(username) of the session bean object called utenteSessionBean, declared inside the managed bean called Neo4jMBean.
I learned that it's not necessary creating and initializing a session bean (as you must do with a normal java object) in managed bean, but it's enough declaring it.
Here is the code of the session bean, which retrieves data from a DB
#Stateless
#LocalBean
public class UtenteSessionBean {
EntityManagerFactory emf = Persistence.createEntityManagerFactory("EnterpriseApplication2-ejbPU");
public boolean CheckUtentebyId(String username){
EntityManager em = emf.createEntityManager();
Query query = em.createNamedQuery("Utente.findByUsername");
query.setParameter("username", username);
List<Utente> Res=query.getResultList();
//completare funzione ctrl+spazio
System.out.println("pre");
System.out.println("pre"+Res.isEmpty());
em.close();
System.out.println("post");
System.out.println("post"+Res.isEmpty());
if(Res.size()>=1)
{
return true;
}
else
{
return false;
}
}
}
Here's the code of the managed bean:
#ManagedBean
#ViewScoped
public class Neo4jMBean {
#EJB
private UtenteSessionBean utenteSessionBean;
static String SERVER_ROOT_URI = "http://localhost:7474/db/data/";
public Neo4jMBean() {
}
public boolean getUser(String username) {
return utenteSessionBean.CheckUtentebyId(username);
}
}
I've searched on StackOverFlow many times a solution for fixing this problem, but I haven't found something that works for me yet.
I fixed it accessing the EJB Components using JNDI.
In few words, if i use an EJB in a managed bean method, i need to add the next lines of code:
InitialContext ic = new InitialContext();
SessionBeanName = (SessionBeanClass) ic.lookup("java:global/NameOfTheApplication/NameOfTheEJBpackage/NameOfTheSessionBean");
It must be surronded by a try-catch statement
Create empty beans.xml file in your WEB-INF folder to enable CDI
Related
I have following code which uses functional style to define two functions for kafka topics
#Bean
public Function<KStream<String, CloudEvent<ClassA>>, KStream<String, CloudEvent<ClassB>>> method1() {
....... //lambda
}
#Bean
public Function<KStream<String, CloudEvent<ClassB>>, KStream<String, CloudEvent<ClassC>>> method2() {
...... //lambda
}
For these two functions I define serdes so
#Bean
public Serde<CloudEventMessage<ClassA>> classASerde(ObjectMapper mapper, Validator validator) {
return StreamsSerdes.classASerde(mapper,validator);
}
#Bean
public Serde<CloudEventMessage<ClassB>> classBSerde(ObjectMapper mapper, Validator validator) {
return StreamsSerdes.classBSerde(mapper,validator);
}
This construction doesn't work as at runtime spring tries to deserialize CloudEvent<ClassB> with Serde of CloutEvent<ClassA>. Is there someway to give hint to use the correct serde for method1 and method2 ?
Secondly I could bypass the above issues by mentioning Serdes in application.properties
spring.application.cloud.stream.kafka.streams.bindings.method1-in-0.consumer.valueSerde=package.serde.StreamsSerdes$ClassASerde
spring.application.cloud.stream.kafka.streams.bindings.method2-in-0.consumer.valueSerde=package.serde.StreamsSerdes$ClassBSerde
However now I get other issues as these Serde classes don't have default constructor. I do need ObjectMapper, Validator from Spring to inject beans (#Service) to perfrom converstions/validations during deserialization.
Has anyone come across similar issues or perhaps have ideas how to resolve them ?
Thanks
I think it is a gap that the nested generics are not working right now in the binder. Do you mind creating an issue in the repository and linking this thread?
As to the second issue that you are running into when providing properties in application.properties, you can try using a workaround. The Serde interface has a configure method that takes a map.
default void configure(Map<String, ?> configs, boolean isKey) {
// intentionally left blank
}
Override this method in your Serde implementation and set those bean objects under some keys.
ObjectMapper mapper;
Validator validator;
#Override
public void configure(Map<String, ?> configs, boolean isKey) {
this.mapper = (ObjectMapper) configs.get("mapper.key");
this.validator = (Validator) configs.get("validator.key");
}
You need to remove accessing them from the constructor and use those fields directly for deserialization and serialization.
Then you provide this bean in your application to populate the map:
#Bean
public StreamsBuilderFactoryBeanCustomizer streamsBuilderFactoryBeanCustomizer(ObjectMapper mapper, Validator validator) {
return factoryBean -> {
factoryBean.getStreamsConfiguration().put("mappeer.key", mapper);
factoryBean.getStreamsConfiguration().put("validator.key", validator);
};
}
I haven't tried this code in an application, but it is something that you can try and see if it works with your code.
When using spring-data-rest there is a post processing of Resource classes returned from Controllers (e.g. RepositoryRestControllers). The proper ResourceProcessor is called in the post processing.
The class responsible for this is ResourceProcessorHandlerMethodReturnValueHandler which is part of spring-hateoas.
I now have a project that only uses spring-hateoas and I wonder how to configure ResourceProcessorHandlerMethodReturnValueHandler in such a scenario. It looks like the auto configuration part of it still resides in spring-data-rest.
Any hints on how to enable ResourceProcessorHandlerMethodReturnValueHandler in a spring-hateoas context?
I've been looking at this recently too, and documentation on how to achieve this is non-existent. If you create a bean of type ResourceProcessorInvokingHandlerAdapter, you seem to lose the the auto-configured RequestMappingHandlerAdapter and all its features. As such, I wanted to avoid using this bean or losing the WebMvcAutoConfiguration, since all I really wanted was the ResourceProcessorHandlerMethodReturnValueHandler.
You can't just add a ResourceProcessorHandlerMethodReturnValueHandler via WebMvcConfigurer.addReturnValueHandlers, because what we need to do is actually override the entire list, as is what happens in ResourceProcessorInvokingHandlerAdapter.afterPropertiesSet:
#Override
public void afterPropertiesSet() {
super.afterPropertiesSet();
// Retrieve actual handlers to use as delegate
HandlerMethodReturnValueHandlerComposite oldHandlers = getReturnValueHandlersComposite();
// Set up ResourceProcessingHandlerMethodResolver to delegate to originally configured ones
List<HandlerMethodReturnValueHandler> newHandlers = new ArrayList<HandlerMethodReturnValueHandler>();
newHandlers.add(new ResourceProcessorHandlerMethodReturnValueHandler(oldHandlers, invoker));
// Configure the new handler to be used
this.setReturnValueHandlers(newHandlers);
}
So, without a better solution available, I added a BeanPostProcessor to handle setting the List of handlers on an existing RequestMappingHandlerAdapter:
#Component
#RequiredArgsConstructor
#ConditionalOnBean(ResourceProcessor.class)
public class ResourceProcessorHandlerMethodReturnValueHandlerConfigurer implements BeanPostProcessor {
private final Collection<ResourceProcessor<?>> resourceProcessors;
#Override
public Object postProcessAfterInitialization(Object bean, String beanName)
throws BeansException {
if (bean instanceof RequestMappingHandlerAdapter) {
RequestMappingHandlerAdapter requestMappingHandlerAdapter = (RequestMappingHandlerAdapter) bean;
List<HandlerMethodReturnValueHandler> handlers =
requestMappingHandlerAdapter.getReturnValueHandlers();
HandlerMethodReturnValueHandlerComposite delegate =
handlers instanceof HandlerMethodReturnValueHandlerComposite ?
(HandlerMethodReturnValueHandlerComposite) handlers :
new HandlerMethodReturnValueHandlerComposite().addHandlers(handlers);
requestMappingHandlerAdapter.setReturnValueHandlers(Arrays.asList(
new ResourceProcessorHandlerMethodReturnValueHandler(delegate,
new ResourceProcessorInvoker(resourceProcessors))));
return requestMappingHandlerAdapter;
}
else return bean;
}
}
This has seemed to work so far...
I basically am trying to inject a #Stateless bean with a local interface into a class annotated with #Named! My understanding is that injection is only possible when the injection point is managed (makes perfect sense), so for example it wouldn't be possible to inject into a POJO but you could inject into a Servlet, a JSF managed or another EJB.
I would have thought that it would have been possible to subsequently use it with #Named! However I get a NullPointerException that specifically seems to imply that this in fact doesn't seem possible!?
My classes look like this (stripped for clarity);
#Named
public class EmailUtil {
// Logger-------------------------------------------------------------------
private static final Logger LOG = Logger.getLogger(EmailUtil.class.getName());
// Constructor--------------------------------------------------------------
public EmailUtil() {
}
// EJB----------------------------------------------------------------------
#EJB AuditDAO audit;
// Methods------------------------------------------------------------------
public void sendEmail(
String emailSender,
String emailRecipient,
String emailSubject,
String emailHtmlBody,
String emailTextBody) throws FailedEmailException {
... code removed for clarity ...
// Call Amazon SES to send the message
try {
new SES().getClient().sendEmail(request);
// Create an audit log of the event
audit.create("Email sent to " + emailSender);
} catch (AmazonClientException ace) {
LOG.log(Level.SEVERE, ace.getMessage(), ace);
throw new FailedEmailException();
} catch (Exception e) {
LOG.log(Level.SEVERE, e.getMessage(), e);
}
}
}
#Stateless
public class AuditDAOImpl implements AuditDAO {
// Logger-------------------------------------------------------------------
private static final Logger LOG = Logger.getLogger(AuditDAOImpl.class.getName());
// EntityManager------------------------------------------------------------
#PersistenceContext(unitName = "iConsultPU")
private EntityManager em;
#Override
public void create(String event) {
String subject;
try {
/*
* If the current subject has authenticated and created a session we
* want to register their ID. However it is possible that a subject
* does not have an ID so we want to set it to unknown.
*/
subject = SecurityUtils
.getSubject()
.getPrincipals()
.asList()
.get(1)
.toString();
} catch (Exception e) {
subject = "UNKNOWN";
}
Audit audit = new Audit();
audit.setUserId(subject);
audit.setEventTime(Calendar.getInstance());
audit.setEvent(event);
em.persist(audit);
}
}
#Local
public interface AuditDAO {
public void create(String event);
}
I've tried using #Inject as well but that doesn't seem to work either. Have I misunderstood the specification or just poorly implemented it?
You should be injecting your dependencies. So if your EmailUtil is being manually constructed, injection won't work. It needs to be container managed. So if you use a servlet, or any managed bean, you can #Inject it. CDI injection only works for managed objects.
You can do some additional work arounds, such as manually invoking it against a constructed instance. Take a look at this question for an example like that: Parallel webservices access in a Weld CDI environment
Do you have the beans.xml in the correct location? Injection for #Named (and other CDI beans) is handled by CDI, which isn't started unless you have the beans.xml file in the correct location (WEB-INF for war and META-INF for jar).
I'm attempting to use Unity to inject a dependency per this article:
http://www.asp.net/web-api/overview/extensibility/using-the-web-api-dependency-resolver
Here is what I have in my global.asax
void ConfigureApi(HttpConfiguration config)
{
var unity = new UnityContainer();
unity.RegisterType<CustomerController>();
unity.RegisterType<TPS.Data.Can.IUnitOfWork, TPS.Data.Can.EFRepository.UnitOfWork>(new HierarchicalLifetimeManager());
config.DependencyResolver = new IoCContainer(unity);
}
protected void Application_Start()
{
AreaRegistration.RegisterAllAreas();
FilterConfig.RegisterGlobalFilters(GlobalFilters.Filters);
RouteConfig.RegisterRoutes(RouteTable.Routes);
BundleConfig.RegisterBundles(BundleTable.Bundles);
ConfigureApi(GlobalConfiguration.Configuration);
}
Here is my API controller:
public class CustomerController : ApiController
{
private TPS.Data.Can.IRepository<tblCustomer> _repo;
private TPS.Data.Can.IUnitOfWork _uow;
public CustomerController() { }
public CustomerController(TPS.Data.Can.IUnitOfWork uow) {
_uow = uow;
_repo = uow.CustomerRepository;
}
// GET api/customer/5
public IEnumerable<Customer> Get()
{
string identity = HttpContext.Current.User.Identity.Name;
//REFACTOR THIS
if (String.IsNullOrWhiteSpace(identity))
identity = "chardie";
var customers = from c in _repo.Get()
where c.SalesRep == identity
select new Customer
{
IDCUST = null,
CustCode = c.CustCode,
CustName = c.CustName
};
return customers.ToList();
}
This works when I first start debugging my application. If I set a breakpoint in the parameterized constructor, the breakpoint will be hit when I hit the Web API for the first time. When I hit refresh in my browser, the constructor does not get called, the dependency doesn't get injected, and the Get() action throws an exception because the expected repository is null.
Can anyone tell me why my constructor isn't being called after the first request?
Thanks!
Chris
EDIT
FWIW, I removed the parameterless constructor entirely from the Web API controller, and on my second request to it, I get the exception:
Type 'TPS.Website.Api.CustomerController' does not have a default constructor
So it appears I'm getting my repo dependency injected on the first request, but after that every instantiation of the Web API controller is done through the parameterless constructor.
You're not specifying a lifecycle for the controller. MSDN states
If you do not specify a value for the lifetime, the instance will have
the default container-controlled lifetime. It will return a reference
to the original object on each call to Resolve.
If the IUnitOfWork dependency is transient, then the controller should be transient too. So try
unity.RegisterType<CustomerController>(new TransientLifetimeManager());
This might not solve the whole problem but it sounds like part of it. You certainly shouldn't need the parameterless constructor.
I had this as I was returning my resolver for my dependency scope using this and then disposing the container in the dispose. So after the first request the container was disposed.
Looks like it's because you're not using singleton pattern for the Unity Container.
Have a private static variable instead of the var container = new UnityContainer();
internal static Lazy<IUnityContainer> container = new Lazy<IUnityContainer>(() => new UnityContainer());
Then access within code using the .Value property.
I'm new to EJB and I'm facing my first problem. I'm trying to use an #Schedule method contained in a Stateless EJB. I'd like this method to use a private member variable which would be set at bean creation:
Here's a short example:
#Singleton
#LocalBean
#Startup
public class Starter {
#PostActivate
private void postActivate() {
ScheduleEJB scheduleEjb = new ScheduleEJB("Hello");
}
}
And the schedule bean:
#Stateless
#LocalBean
public class ScheduleEJB {
private String message;
public ScheduleEJB() {
super();
}
public ScheduleEJB(String message) {
super();
this.message= message;
}
#Schedule(second="*/3", minute="*", hour="*", dayOfMonth="*", dayOfWeek="*", month="*", year="*")
private void printMsg() {
System.out.println("MESSAGE : " + message);
}
}
The problem is that my "message" variable is always null when printed in the printMsg() method... What's the best way to achieve this?
Thanks for your help !
You're mixing few things here.
The #PostActivate annotation is to be used on Stateful Session Beans (SFSB), and you use it on the singleton. I guess that you mean the #PostConstruct method which applies to every bean which lifecycle is managed by the container.
You're using a constructor from your EJB. You cannot do:
ScheduleEJB scheduleEjb = new ScheduleEJB("Hello");
as it creates just an instance of this class. It's not an EJB - the container didn't create it, so this class does not have any EJB nature yet.
That's the whole point of dependency injection - you just define what you want and the container is responsible for providing you with an appropriate instance of the resource.
The Stateless Bean (SLSB) is not intented to hold the state. The SFSB is. Even if you would set the message in one SLSB method (i.e. in some ScheduleEJB#setMessage(String) method) than you need to remember that the EJB's are pooled. You don't have any guarantee that the next time you invoke a method on the ScheduleEJB you will get to the same instance.
In your case it would be the easies solution just to add the #Schedule method to your singleton class. Than you can define the variable of your choice in the #PostConstruct method. You can be sure that there is only one Singleton instance per JVM, so your variable will be visible in the Schedule annotated method of the same class.
HTH.