I have a factory class
#ApplicationScoped /* 'ApplicationScoped' is not a must */
class MyFactory {
#Inject
private IService aService;
...
}
And an JAXB annotated class
#XmlRootElement(name = "item")
class AnItem {
#Inject
MyFactory myFactory;
...
}
AnItem is instantiated by JAXB from an XML file.
The problem is that myFactory is null. If I replace this by
...
MyFactory myFactory = new MyFactory();
...
then myFactory.aService is null.
How can I use dependency injection within classes created by JAXB?
The following solution is inspired by a Block of Adam Warski, see also BeanManager Javadoc
At first I'll need two utility methods:
import javax.enterprise.inject.spi.Bean;
import javax.enterprise.inject.spi.BeanManager;
import javax.naming.InitialContext;
import javax.naming.NamingException;
public class Utils {
public static BeanManager getBeanManager() {
try {
InitialContext initialContext = new InitialContext();
return (BeanManager) initialContext.lookup("java:comp/BeanManager");
} catch (NamingException e) {
throw new RuntimeException("Failed to retrieve BeanManager!", e);
}
}
public static <T> T getBean(Class<T> c) {
T result = null;
BeanManager bm = getBeanManager();
Set<Bean<?>> beans = bm.getBeans(c);
if (! beans.isEmpty()) {
Bean<?> bean = beans.iterator().next();
result = c.cast(bm.getReference(bean, c, bm.createCreationalContext(bean)));
}
return result;
}
}
Class AnItem has then to be changed like this:
#XmlRootElement(name = "item")
class AnItem {
MyFactory myFactory = Utils.getBean(MyFactory.class);
...
}
I think you have some code in the wrong class, which is causing dependencies to be around the wrong way, which in turn makes the objects difficult to construct correctly.
Item looks like a newable class (sometimes known as an entity). Newable classes are not created by your container, but are created by service classes. Jaxb is an example of a service. The service classes are created by your DI container.
I would re-evaluate your need to have Item hold a reference to myFactory. You have not shown this in your question, but there must be a method in Item that makes a call to something in myFactory.
This code should be moved out of Item into a different class (perhaps a new service) that accepts an item as a parameter.
CDI beans are supposed to be container managed, meaning if you use new to create them you don't get any of the container services (injection, interception, decorators, etc). You'd need to #Inject your factory class to have the injection work correctly.
Related
I have a parameterized class that implements the FactoryBean interface:
public class DogFactory<T extends Dog> implements FactoryBean<T> {
// ...
}
What I want is to use this factory for spawning objects of different classes (all of these classes extend Dog). So I imagined that I could do something like the following:
public class ShepherdService {
private DogFactory<Shepherd> shepherdFactory;
public ShepherdService(
#Autowired
DogFactory<Shepherd> shepherdFactory
) {
this.shepherdFactory = shepherdFactory;
}
// ...
}
Alas, I get the following error: Couldn't autowire. No beans of DogService<Shepherd> type found. :-(
How to inject it and use as DogFactory<Shepherd> or DogFactory<Corgi> (not just DogFactory)?
And another question. I also need to pass the Shepherd.class (or Corgi.class) to this bean, so it could "know" at run-time, objects of what exactly class should it produce. Is there a way to do that?
Or should I forget about FactoryBean and instantiate the factory as a regular class? Of course, I could do it this way:
DogFactory<Shepherd> shepherdFactory = new DogFactory<Shepherd>(Shepherd.class);
It would work perfectly, but I'd like to use FactoryBean as I use it for other factories in this project, so I would like to stick to FactoryBean.
Thanks in advance!
Update 1
Maybe I should clarify it more precise. What I need is a factory that could produce objects of different classes. All these classes should be extensions of the certain class (e.g., Shepherd and Corgi - all these classes extend Dog). And as the final result I actually need something like that:
public class DogService<T extend Dog> {
private DogFactory<T> dogFactory;
#Autowired
public DogService(DogFactory<T> dogFactory) {
this.dogFactory = dogFactory;
}
public T spawnDog(Color color) {
T dog = DogFactory.getObject(color);
return dog;
}
}
But it seems that I can't make a "universal" factory with the FactoryBean interface, so I can't do something like that:
public class DogFactory<T extends Dog> implements FactoryBean<T> {
// ...
}
Instead of that I have to do something like the following:
public class ShepherdFactory implements FactoryBean<Shepherd> {
// ...
}
public class CorgiFactory implements FactoryBean<Corgi> {
// ...
}
Is that true?
Thanks!
What I want is to instantiate this factory in another class
If you mean "having the factory injected in the class instead of the bean it creates", you could inject the factory by prefixing its name with an ampersand:
public class ShepherdService {
private DogFactory<Shepherd> shepherdFactory;
#Qualifier("&dogFactory")
public ShepherdService(DogFactory<Shepherd> shepherdService) {
this.shepherdService = shepherdService;
}
}
From the Spring documentation (section 3.8.3):
When you need to ask a container for an actual FactoryBean instance
itself, not the bean it produces, you preface the bean id with the
ampersand symbol & (without quotes) when calling the getBean method of
the ApplicationContext. So for a given FactoryBean with an id of
myBean, invoking getBean("myBean") on the container returns the
product of the FactoryBean, and invoking getBean("&myBean") returns
the FactoryBean instance itself.
Furthermore, my guess is that the FactoryBean is not picked up as a Spring bean as your snippets did not contain an XML config section, a Java config section, or a #Component annotation. I would explicitly declare the factory bean in a #Configuration annotated class, or annotate the factory class with #Component.
[edit]
But it seems that I can't make a "universal" factory with the
FactoryBean interface, so I can't do something like that:
You could still have a single Configuration class in which you declare all the factory beans.
#Configuration
public class DogFactoryConfig {
#Bean
public DogFactory<Shepherd> shepherdFactory() {
return new DogFactory<Shepherd>();
}
#Bean
public DogFactory<Corgi> corgiFactory() {
return new DogFactory<Corgi>();
}
}
And remove the #Component annotation from your DogFactory if it is present.
I have a java interface say ITest implemented by two classes Class1 and Class2. Now I have a factory class which I use to decide which implementation to return. like
if(something)
return new Class1()
else
return new Class2()
Problem is that I have autowired field in Class1 which doesn't get instantiated,, but the same autowiring works in other classes which were instantiated via autowiring.
Here is code for Class1
#Componene
public Class1 implements ITest{
#Autowired
private SomeClass obj;
}
Not sure how to get around this problem. As autowiring for SomeClass works fine in Other classes.
Inject applicationContext in your factory class and use it for bean creation:
#Autowired private ApplicationContext applicationContext;
......
......
if(something){
return applicationContext.getBean("com.xyz.Class1");
}
......
......
OR you can use #Configurable on top of Class1 and Class2. This needs AspectJ weaving to be enabled. Spring will then magically create beans when you use new.
It strongly depends of what exactly do you need, but you can:
Define the object returned by factory as prototype-scope and inject it to singleton, for more details look at: https://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#beans-factory-scopes-sing-prot-interaction
Then whole magic is done by Spring
If you just want to switch between two different stateless implementations you can inject both of them to factory and return an existing bean
#Compoment class Factory {
#Autowired
Class1 class1Instance;
#Autowired
Class2 classInstance;
...
if(something)
return class1Instance;
else
return class2Instance;
...
}
}
But please make sure that both injected classes have no state.
Make factory managed by Spring, both classes not-managed by Spring and inject dependencies manually:
public Class1 implements ITest{
private SomeClass obj;
public Class1(SomeClass obj) {
this.obj=obj;}
}
and in factory:
#Autowired
private SomeClass obj;
...
if(something)
return new Class1(obj);
else
return new Class2(obj);
At first glance looks strange, by that way you can e.g. separate domain and application/infrastructure parts.
You could use your Main Configuration class which is annotated with #SpringBootApplication or #Configuration.
Example:
#SpringBootApplication
public class YourApp {
public static void main(String[] args) {
SpringApplication.run(YourApp.class, args);
}
#Autowired
private CsvBeanRepository repo;
#Bean
public InterfaceSome some() {
if(something) {
return new Some(repo);
} else {
return new Some2(repo);
}
}
}
inside a #SpringBootApplication class or a #Configuration class you can #Autowire your classes normally and use them as parameters for your factory.
I would suggest to use #value annotation for this scenario.
Example
MyClass{
Object getObjectFromFactory()
{
if(something)
return new Class1()
else
return new Class2()
}
}
then you can use it like below
#Value("#{MyClass.getObjectFromFactory}")
private Object myObject;
In a java-spring web-app I would like to be able to dynamically inject beans.
For example I have an interface with 2 different implementations:
In my app I'm using some properties file to configure injections:
#Determines the interface type the app uses. Possible values: implA, implB
myinterface.type=implA
My injections actually loaded conditionally relaying on the properties values in the properties file. For example in this case myinterface.type=implA wherever I inject MyInterface the implementation that will be injected will be ImplA (I accomplished that by extending the Conditional annotation).
I would like that during runtime - once the properties are changed the following will happen (without server restart):
The right implementation will be injected. For example when setting myinterface.type=implB ImplB will be injected where-ever MyInterface is used
Spring Environment should be refreshed with the new values and re-injected as well to beans.
I thought of refreshing my context but that creates problems.
I thought maybe to use setters for injection and re-use those setters once properties are re-configured. Is there a working practice for such a requirement?
Any ideas?
UPDATE
As some suggested I can use a factory/registry that holds both implementations (ImplA and ImplB) and returns the right one by querying the relevant property.
If I do that I still have the second challenge - the environment. for example if my registry looks like this:
#Service
public class MyRegistry {
private String configurationValue;
private final MyInterface implA;
private final MyInterface implB;
#Inject
public MyRegistry(Environmant env, MyInterface implA, MyInterface ImplB) {
this.implA = implA;
this.implB = implB;
this.configurationValue = env.getProperty("myinterface.type");
}
public MyInterface getMyInterface() {
switch(configurationValue) {
case "implA":
return implA;
case "implB":
return implB;
}
}
}
Once property has changed I should re-inject my environment. any suggestions for that?
I know I can query that env inside the method instead of constructor but this is a performance reduction and also I would like to think of an ider for re-injecting environment (again, maybe using a setter injection?).
I would keep this task as simple as possible. Instead of conditionally load one implementation of the MyInterface interface at startup and then fire an event that triggers dynamic loading of another implementation of the same interface, I would tackle this problem in a different way, that is much simpler to implement and maintain.
First of all, I'd just load all possible implementations:
#Component
public class MyInterfaceImplementationsHolder {
#Autowired
private Map<String, MyInterface> implementations;
public MyInterface get(String impl) {
return this.implementations.get(impl);
}
}
This bean is just a holder for all implementations of the MyInterface interface. Nothing magic here, just common Spring autowiring behavior.
Now, wherever you need to inject a specific implementation of MyInterface, you could do it with the help of an interface:
public interface MyInterfaceReloader {
void changeImplementation(MyInterface impl);
}
Then, for every class that needs to be notified of a change of the implementation, just make it implement the MyInterfaceReloader interface. For instance:
#Component
public class SomeBean implements MyInterfaceReloader {
// Do not autowire
private MyInterface myInterface;
#Override
public void changeImplementation(MyInterface impl) {
this.myInterface = impl;
}
}
Finally, you need a bean that actually changes the implementation in every bean that has MyInterface as an attribute:
#Component
public class MyInterfaceImplementationUpdater {
#Autowired
private Map<String, MyInterfaceReloader> reloaders;
#Autowired
private MyInterfaceImplementationsHolder holder;
public void updateImplementations(String implBeanName) {
this.reloaders.forEach((k, v) ->
v.changeImplementation(this.holder.get(implBeanName)));
}
}
This simply autowires all beans that implement the MyInterfaceReloader interface and updates each one of them with the new implementation, which is retrieved from the holder and passed as an argument. Again, common Spring autowiring rules.
Whenever you want the implementation to be changed, you should just invoke the updateImplementations method with the name of the bean of the new implementation, which is the lower camel case simple name of the class, i.e. myImplA or myImplB for classes MyImplA and MyImplB.
You should also invoke this method at startup, so that an initial implementation is set on every bean that implements the MyInterfaceReloader interface.
I solved a similar issue by using org.apache.commons.configuration.PropertiesConfiguration and org.springframework.beans.factory.config.ServiceLocatorFactoryBean:
Let VehicleRepairService be an interface:
public interface VehicleRepairService {
void repair();
}
and CarRepairService and TruckRepairService two classes that implements it:
public class CarRepairService implements VehicleRepairService {
#Override
public void repair() {
System.out.println("repair a car");
}
}
public class TruckRepairService implements VehicleRepairService {
#Override
public void repair() {
System.out.println("repair a truck");
}
}
I create an interface for a service factory:
public interface VehicleRepairServiceFactory {
VehicleRepairService getRepairService(String serviceType);
}
Let use Config as configuration class:
#Configuration()
#ComponentScan(basePackages = "config.test")
public class Config {
#Bean
public PropertiesConfiguration configuration(){
try {
PropertiesConfiguration configuration = new PropertiesConfiguration("example.properties");
configuration
.setReloadingStrategy(new FileChangedReloadingStrategy());
return configuration;
} catch (ConfigurationException e) {
throw new IllegalStateException(e);
}
}
#Bean
public ServiceLocatorFactoryBean serviceLocatorFactoryBean() {
ServiceLocatorFactoryBean serviceLocatorFactoryBean = new ServiceLocatorFactoryBean();
serviceLocatorFactoryBean
.setServiceLocatorInterface(VehicleRepairServiceFactory.class);
return serviceLocatorFactoryBean;
}
#Bean
public CarRepairService carRepairService() {
return new CarRepairService();
}
#Bean
public TruckRepairService truckRepairService() {
return new TruckRepairService();
}
#Bean
public SomeService someService(){
return new SomeService();
}
}
By using FileChangedReloadingStrategy your configuration be reload when you change the property file.
service=truckRepairService
#service=carRepairService
Having the configuration and the factory in your service, let you can get the appropriate service from the factory using the current value of the property.
#Service
public class SomeService {
#Autowired
private VehicleRepairServiceFactory factory;
#Autowired
private PropertiesConfiguration configuration;
public void doSomething() {
String service = configuration.getString("service");
VehicleRepairService vehicleRepairService = factory.getRepairService(service);
vehicleRepairService.repair();
}
}
Hope it helps.
If I understand you correctly then the goal is not to replace injected object instances but to use different implementations during interface method call depends on some condition at run time.
If it is so then you can try to look at the Sring TargetSource mechanism in combination with ProxyFactoryBean. The point is that proxy objects will be injected to beans that uses your interface, and all the interface method calls will be sent to TargetSource target.
Let's call this "Polymorphic Proxy".
Have a look at example below:
ConditionalTargetSource.java
#Component
public class ConditionalTargetSource implements TargetSource {
#Autowired
private MyRegistry registry;
#Override
public Class<?> getTargetClass() {
return MyInterface.class;
}
#Override
public boolean isStatic() {
return false;
}
#Override
public Object getTarget() throws Exception {
return registry.getMyInterface();
}
#Override
public void releaseTarget(Object target) throws Exception {
//Do some staff here if you want to release something related to interface instances that was created with MyRegistry.
}
}
applicationContext.xml
<bean id="myInterfaceFactoryBean" class="org.springframework.aop.framework.ProxyFactoryBean">
<property name="proxyInterfaces" value="MyInterface"/>
<property name="targetSource" ref="conditionalTargetSource"/>
</bean>
<bean name="conditionalTargetSource" class="ConditionalTargetSource"/>
SomeService.java
#Service
public class SomeService {
#Autowired
private MyInterface myInterfaceBean;
public void foo(){
//Here we have `myInterfaceBean` proxy that will do `conditionalTargetSource.getTarget().bar()`
myInterfaceBean.bar();
}
}
Also if you want to have both MyInterface implementations to be Spring beans, and the Spring context could not contains both instances at the same time then you can try to use ServiceLocatorFactoryBean with prototype target beans scope and Conditional annotation on target implementation classes. This approach can be used instead of MyRegistry.
P.S.
Probably Application Context refresh operation also can do what you want but it can cause other problems such as performance overheads.
This may be a duplicate question or at least very similar, anyway I answered this sort of question here: Spring bean partial autowire prototype constructor
Pretty much when you want a different beans for a dependency at run-time you need to use a prototype scope. Then you can use a configuration to return different implementations of the prototype bean. You will need to handle the logic on which implementation to return yourself, (they could even be returning 2 different singleton beans it doesn't matter) But say you want new beans, and the logic for returning the implementation is in a bean called SomeBeanWithLogic.isSomeBooleanExpression(), then you can make a configuration:
#Configuration
public class SpringConfiguration
{
#Bean
#Autowired
#Scope("prototype")
public MyInterface createBean(SomeBeanWithLogic someBeanWithLogic )
{
if (someBeanWithLogic .isSomeBooleanExpression())
{
return new ImplA(); // I could be a singleton bean
}
else
{
return new ImplB(); // I could also be a singleton bean
}
}
}
There should never be a need to reload the context. If for instance, you want the implementation of a bean to change at run-time, use the above. If you really need to reload your application, because this bean was used in constructors of a singleton bean or something weird, then you need to re-think your design, and if these beans are really singleton beans. You shouldn't be reloading the context to re-create singleton beans to achieve different run-time behavior, that is not needed.
Edit The first part of this answer answered the question about dynamically injecting beans. As asked, but I think the question is more of one: 'how can I change the implementation of a singleton bean at run-time'. This could be done with a proxy design pattern.
interface MyInterface
{
public String doStuff();
}
#Component
public class Bean implements MyInterface
{
boolean todo = false; // change me as needed
// autowire implementations or create instances within this class as needed
#Qualifier("implA")
#Autowired
MyInterface implA;
#Qualifier("implB")
#Autowired
MyInterface implB;
public String doStuff()
{
if (todo)
{
return implA.doStuff();
}
else
{
return implB.doStuff();
}
}
}
You can use #Resource annotation for injection as originally answered here
e.g.
#Component("implA")
public class ImplA implements MyInterface {
...
}
#Component("implB")
public class ImplB implements MyInterface {
...
}
#Component
public class DependentClass {
#Resource(name = "\${myinterface.type}")
private MyInterface impl;
}
and then set the implementation type in properties file as -
myinterface.type=implA
Be aware that - if interesting to know about - FileChangedReloadingStrategy makes your project highly dependent on the deployment conditions: the WAR/EAR should be exploded by container and your should have direct access to the file system, conditions that are not always met in all situations and environments.
You can use Spring #Conditional on a property value. Give both Beans the same name and it should work as only one Instance will be created.
Have a look here on how to use #Conditional on Services and Components:
http://blog.codeleak.pl/2015/11/how-to-register-components-using.html
public abstract class SystemService {
}
public class FooSystemService extends FileSystemService {
}
public class GoSystemService extends FileSystemService {
}
#Configuration
public class SystemServiceConf {
#Bean
#Conditional(SystemServiceCondition.class)
public SystemService systemService(#Value("${value.key}") value) {
switch (value) {
case A:
return new FooSystemService();
case B:
return new GoSystemService();
default:
throw new RuntimeException("unknown value ");
}
}
}
public class SystemServiceCondition implements Condition {
#Override
public boolean matches(ConditionContext conditionContext, AnnotatedTypeMetadata annotatedTypeMetadata) {
return true;
}
}
I have the following situation:
During the configuration/startup of Spring Boot, I am picking up a list of interfaces using reflections. These interfaces are replaced with a proxy implementation (using java.lang.reflect.Proxy, because I cannot use Spring's AOP). This is working.
There is a super and the actual interface. So I have something like this:
public interface Stream{
}
public interface ExampleStream extends Stream{
doAction();
}
Now I want to use the interfaces in other beans unsing #Inject, e.g.
#Service
public class MyService{
#Inject
private ExampleStream exampleStream;
public void fooBar(){
exampleStream.doAction();
}
}
And there is the method to initialize the proxy:
...
StreamInvocationHandler invoHandler = ... // this implements InvocationHandler (the proxy)
ClassLoader cl = ClassUtils.getDefaultClassLoader();
Class<? extends Stream> stream = ... // fetch the class, which is ExampleStream.class
Object impl = Proxy.newProxyInstance(cl, new Class[]{stream}, invoHandler);
ExampleStream exampleStream = (ExampleStream)impl;
// this is working
exampleStream.doAction();
The mechanism should be equal to the spring data repositories (except of the #Repository annotation and so on...)
But now, I don't know how to inject. Because of some SO answers, I tried to implement ApplicationContextAware as follows:
public void setApplicationContext(ApplicationContext applicationContext) throws BeansException {
... // stuff from above
AutowireCapableBeanFactory beanFactory = applicationContext.getAutowireCapableBeanFactory();
beanFactory.autowireBean(impl);
beanFactory.initializeBean(impl, "exampleBean");
}
This did not work (field exampleStram in myservice has no qualifying bean...). I also tried another suggestion with a similar solution using BeanDefinitionRegistryPostProcessor, but this is only intended for bean definitions.
Where and how can I inject those kinds of self created beans?
I have a group of classes which are instantiated by reflection, hence these are not managed by the CDI container, and no injections are made by the context. My question is, is there any way to register these classes in the CDI context, so the classes get managed by the context?
Bellow, is how I create the classes:
String clazz = "org.myorg.thisIsMyClass";
MyClass myClass = Class.forName(clazz).newInstance(); // myClass instance not managed by CDI
How do I make the instance of myClass managed by the CDI container?
If your classes were registered as bean by the container you can use programmatic lookup to get them easily.
#Inject
#Any
Instance<Object> myBeans;
public Object getMyBeanFromClassName(String className) throws Exception{
Class clazz = Class.forName(className);
return myBeans.select(clazz).get();
}
Et voilà.
Following the comments of #AdrianMitev, I finally ended up writing this class which returns an instance of a Managed CDI Bean given its class name (elName) or class type:
public class GetInstance {
public static Object of(String elName) {
BeanManager bm = getBeanManager();
Bean<?> bean = bm.resolve(bm.getBeans(elName));
return bm.getReference(bean, bean.getBeanClass(), bm.createCreationalContext(bean));
}
#SuppressWarnings("unchecked")
public static <T> T of(Class<T> clazz) {
BeanManager bm = getBeanManager();
Bean<?> bean = bm.resolve(bm.getBeans(clazz));
return (T) bm.getReference(bean, bean.getBeanClass(), bm.createCreationalContext(bean));
}
private static BeanManager getBeanManager() {
try {
return (BeanManager) new InitialContext().lookup("java:comp/BeanManager");
} catch (NamingException e) {
e.printStackTrace();
}
return null;
}
}
So, if you have a class like this one:
#Named
public class FooClass {
...
}
You can get an a managed CDI instance using:
FooClass fC = GetInstance.of(FooClass.class);
or using its elName
FooClass fC = (FooClass) GetInstance.of("fooClass");
or you can select the name to use:
#Named(value="CustomFooClassName")
public class FooClass {
...
}
And using:
FooClass fC = (FooClass) GetInstance.of("CustomFooClassName");
The easiest way to do let CDI to manage your class is to use a producer.
public class MyProducers {
#Produces
#RequestScoped //Could be any scope here
#FromReflection //a qualifier to distinguish this Bean of type Object from others. Would be better to have a more specific bean type if all your class come from the same ancestor.
public Object produceMyClass()
{
String clazz = "org.myorg.thisIsMyClass";
Object myObject = Class.forName(clazz).newInstance();
return myObject;
}
}
Somewhere else in your code you can use this producer like this :
#Inject
#FromReflection
Object myBean;
** Edit : adding InjectionPoint usage. **
Now you can enhance your producer by injecting it's InjectionPointin its parameter list. You can then use the metadata of the injection point (i.e qualifier) to dynamically find your class.
First you have to add a field to store the class name in your #FromReflection qualifier :
#Qualifier
#Target({TYPE, METHOD, PARAMETER, FIELD})
#Retention(RUNTIME)
#Documented
public #interface FromReflection {
#Nonbinding String value(); // classname will be store here
}
then you use this info in your producer :
public class MyProducers {
private String extractClassName(InjectionPoint ip) {
for (Annotation annotation : ip.getQualifiers()) {
if (annotation.annotationType().equals(FromReflection.class))
return ((FromReflection) annotation).value();
}
throw new IllegalStateException("No #FromReflection on InjectionPoint");
}
#Produces
#FromReflection
public Object produceMyClass(InjectionPoint ip)
{
String clazzNanme = extractClassName(ip);
Object myObject = Class.forName(clazz).newInstance();
return myObject;
}
}
Note that the produced bean has to be in #Dependent scope, it's a constraint when injecting InjectionPoint in the producer parameters.
You can now inject your bean like that :
#Inject
#FromReflection("org.myorg.thisIsMyClass")
Object myBean;
Now if you want to decide at runtime which class you want to build, you'll have to use the CDI programmatic lookup feature which allow you to create synthetic qualifier.
First create an AnnotationLiteral for your qualifier to be able to instantiate a a new qualifier.
public class FromReflectionLiteral extends AnnotationLiteral<FromReflection> implements FromReflection {
private String value;
public FromReflectionLiteral(String value) {
this.value = value;
}
#Override
public String value() {
return value;
}
}
Then you'll use the Instance<> bean to request for your final bean.
public class ConsumingBean {
#Inject
#Any
Instance<Object> myBeanInstance;
public Object getBeanFor(String className) {
return myBeanInstance.select(new FromReflectionLiteral(className)).get();
}
...
}
Next step would be to use a portable extension...
You can make CDI aware of your instance by not instantiating the bean yourself (as i pointed in your previous post) but to let CDI instantiate the bean. Here is a sample code for that:
InitialContext initialContext = new InitialContext();
BeanManager bm = (BeanManager) initialContext.lookup("java:comp/BeanManager");
//List all CDI Managed Beans and their EL-accessible name
Set<Bean<?>> beans = bm.getBeans(AbstractBean.class, new AnnotationLiteral<Any>() {});
List<Object> beanInstances = new ArrayList<Object>();
for (Bean bean : beans) {
CreationalContext cc = bm.createCreationalContext(bean);
//Instantiates bean if not already in-service (undesirable)
Object beanInstance = bm.getReference(bean, bean.getBeanClass(), cc);
beanInstances.add(beanInstance);
}
return beanInstances;
If you are sure that there is only one bean of the specific type you can use beans.iterator.next().