I am seeing a peculiar behavior in Spring 3.2.5
One of my beans is created as a consequence of AbstractBeanFactory#getType
Then Spring throws an exception along the lines of
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'A' defined in class path resource [config.xml]: Cannot resolve reference to bean 'B' while setting constructor argument; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'B': Requested bean is currently in creation: Is there an unresolvable circular reference?
As the result of that exception, my bean is destroyed.
Later, my bean is created again, from a different getType() call. Tghis time Spring does not have any circular path problems.
Eventually, the entire context is created successfully, with the second copy of my bean retained as singleton.
My question is - is that behavior normal? Or am I doing something wrong? My bean has side effects in its init() method, so if this is a normal behavior of Spring, I'll need to add a destroy() method to it...
Edit:
To clarify the questions about the exception: The beans mentioned in exception are not exactly relevant because the context (including the beans A and B) is eventually created successfully, so there really is no circular dependency. However, for the completeness' sake, bean A takes bean B as constructor argument.
Related
As far as i know:
BeanFactory creates beans according to its definitions.
Then sends it to BeanPostProcessor to invoke postProcessBeforeInitialization().
Receives it back and provides init() method.
BeanPostProcessor with postProcessAfterInitialization() method.
Bean finally configured and sent into IoC container.
My question is: "At what stage does dependency injection take place?".
Really curious on how it works under the hood.
Dependency injection typically takes place during the initialization of a bean, after the bean has been instantiated by the BeanFactory, but before the bean is fully initialized and ready to be used by the application.
The process typically works as follows:
The BeanFactory creates an instance of the bean according to its definitions.
The BeanPostProcessor's postProcessBeforeInitialization() method is invoked, which allows for any pre-initialization processing to take place, such as setting up some initial values or performing some other setup tasks.
The BeanFactory then proceeds to set the bean's properties and dependencies, using either setter injection or constructor injection, which are the two most common forms of dependency injection. This step is where the actual injection of dependencies takes place.
The BeanPostProcessor's postProcessAfterInitialization() method is invoked, which allows for any post-initialization processing to take place, such as performing some validation or other tasks on the fully initialized bean.
The Bean is finally configured and sent into IoC container.
It's important to note that the step 2 and 4 are optional, and not all BeanPostProcessor implementation will invoke them.
BeanPostProcessor is an interface that allows for additional processing to be done on bean instances before and after their initialization. It is useful for performing custom logic on beans during the initialization process, but it is not necessary for dependency injection to take place.
I would like to mock a Bean (using mockito) that is defined like so
#Bean("idGenerator")
public Supplier<UUID> idGenerator() {
return () -> UUID.randomUUID();
}
In a SpringBootTest-class I get an error using #MockBean indicating, that that Bean cannot be mocked (due to some limitations in the JVM? - sorry, I don't have the stacktrace at hand right now).
I came up with a workaround that does not use Mocks but an additional field in a #TestConfiguration so that the return-value of the supplier can be specified externally.
Since I don't really like that workaround (and my colleagues won't either), I hope there is a proved pattern or the realization I am doing that mocking wrong.
Edit
Here is the stacktrace I am getting. As Markus pointed out - the standard unit-tests work - it seems to be a shortcoming of cucumber-java:
Before All/After All failed
io.cucumber.core.exception.CompositeCucumberException: There were 15 exceptions. The details are in the stacktrace below.
at io.cucumber.core.runtime.RethrowingThrowableCollector.getThrowable(RethrowingThrowableCollector.java:57)
at io.cucumber.core.runtime.CucumberExecutionContext.getThrowable(CucumberExecutionContext.java:102)
at io.cucumber.core.runtime.CucumberExecutionContext.finishTestRun(CucumberExecutionContext.java:97)
at io.cucumber.core.runtime.Runtime.execute(Runtime.java:96)
at io.cucumber.core.runtime.Runtime.run(Runtime.java:87)
at io.cucumber.core.cli.Main.run(Main.java:87)
at io.cucumber.core.cli.Main.main(Main.java:30)
Suppressed: java.lang.IllegalStateException: Failed to load ApplicationContext
at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:98)
at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:124)
at io.cucumber.spring.TestContextAdaptor.<init>(TestContextAdaptor.java:32)
at io.cucumber.spring.SpringFactory.start(SpringFactory.java:120)
at io.cucumber.core.runner.Runner.buildBackendWorlds(Runner.java:134)
[...]
Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name [...]: Unsatisfied dependency expressed through constructor parameter 5: Initialization of bean failed;
nested exception is org.mockito.exceptions.base.MockitoException:
Cannot mock/spy class BackendApplicationConfiguration$$Lambda$1713/0x00000008018fd980
Mockito cannot mock/spy because :
- VM does not support modification of given type
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:800)
at org.springframework.beans.factory.support.ConstructorResolver.autowireConstructor(ConstructorResolver.java:229)
You can just define it like follows:
#MockBean(name = "idGenerator")
private Supplier<UUID> mockedSupplier;
there is no issue that prevents this from mocking. Would be good to include your stacktrace, as the issue is probably somewhere else.
I'm trying to instanciate a bean which constructor could throw an Exception.
I can't modify this class (given by an external team).
<bean id="myClass" class="myClass" />
The myClass constructor throws Exception.
I've been thinking about extending this class with a Singleton Pattern which is the behavior I want (be sure to instantiate only one instance of MyClass).
Error message :
nested exception is
org.springframework.beans.factory.BeanCreationException: Error
creating bean with name
'myClass'
defined in class path resource
[.../spring_applicationContext.xml]:
Instantiation of bean failed; nested exception is
org.springframework.beans.BeanInstantiationException: Could not
instantiate bean class
[myClass]:
Constructor threw exception; nested exception is
java.lang.ExceptionInInitializerError
Thanks in advance for your answers
I think the problem comes from the fact that my constructor throws an Exception.
My question is : with Spring, is it possible to instanciate a bean with a constructor which could throw an exception ?
If no bean scope is specified in bean configuration file, default to singleton. Your bean myClass is a singleton and you dont need to do anything more.
Spring Doc
Spring beans are by default singletons.
You should provide more of the stacktrace - what you're showing indicates that it is not myClass that is the problem, but the ClassPathXmlApplicationContext constructor that throws an exception - the cause usually follows later in the stacktrace.
Cheers,
As per stack trace, looks like there is an unexpected error either in static block or variable while creating an object of class 'myClass'.
I am trying to create a bean and than trying to inject the same in my Controller but i am getting bean creation failure error.Here is my code
#Service("springSecurityLoginServiceImpl")
public class SpringSecurityLoginServiceImpl implements SpringSecurityLoginService
{
//impl
}
this is how i am trying to inject it in my controller
#Controller
#RequestMapping("springSecurity/login.json")
public class SpringSecurityLoginController
{
#Autowired
#Qualifier("springSecurityLoginServiceImpl")
SpringSecurityLoginService springSecurityLoginService;
}
There is no entry in Spring-MVC-config xml file except these annotation, but when i am starting server facing the following exception
org.springframework.beans.factory.BeanCreationException:
Error creating bean with name 'org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping#0'
defined in ServletContext resource [/WEB-INF/config/spring-mvc-config.xml]:
Initialization of bean failed; nested exception is org.springframework.beans.factory.BeanCreationException:
Error creating bean with name 'springSecurityLoginController':
Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException:
Could not autowire field: com.core.servicelayer.user.SpringSecurityLoginService com.storefront.controllers.pages.SpringSecurityLoginController.springSecurityLoginService;
nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException:
No matching bean of type [com.core.servicelayer.user.SpringSecurityLoginService] found for dependency:
expected at least 1 bean which qualifies as autowire candidate for this dependency.
Dependency annotations: {#org.springframework.beans.factory.annotation.Autowired(required=true),
#org.springframework.beans.factory.annotation.Qualifier(value=springSecurityLoginServiceImpl)}
i am not sure what i am doing wrong or what extra i have to do
SpringSecurityLoginController class refers SpringSecurityLoginService class, for which a bean isn't defined. That much the error says.
It is true, because you've only defined a bean for the class LoginServiceImpl, which doesn't seem to extend SpringSecurityLoginService in any way.
Spring's bean lookup algorithm first searches for beans of which type is, or extends, SpringSecurityLoginService. Then, it narrows the avaialble options using the Qualifier. In this case, no bean is found in the first place...
See Spring doc:
4.11.3 Fine-tuning annotation-based autowiring with qualifiers
Since autowiring by type may lead to multiple candidates, it is often
necessary to have more control over the selection process. One way to
accomplish this is with Spring's #Qualifier annotation. This allows
for associating qualifier values with specific arguments, narrowing
the set of type matches so that a specific bean is chosen for each
argument.
You need that LoginServiceImpl will implement SpringSecurityLoginService, for instance.
EDIT
Since it was just a typo you might be not including SpringSecurityLoginService's package in component-scan tag, in your spring configuration file (as gkamal has already mentioned). You should have there something like:
<context:component-scan base-package="org.example"/>
where org.example should be replaced by SpringSecurityLoginService's package.
When I defined a 'MethodInvokingFactory' bean with 'scope=step', I got an error that the type of the bean can't be determined. It worked fine when I replaced 'scope=step' with 'lazy-init=true'. As per my knowledge, both are used for the late binding of the beans, except for that one difference. Are there any other differences between these two ways? Also, is my usage correct?
Please let me know your thoughts about this.
To answer to your question from low-level perspective:
lazy-init="true" means that bean will not be instantiated when the context is created, but will be created when it is referred e.g. by another bean. I think this is clear, also from #AravindA comment.
Scoped bean works in different manner. When context is created this bean is wrapped into additional proxy object (by default created by CGLIB), which is passed to the bean that refers it (this proxy is by default singleton, e.g. shared). So each time the method is invoked on the proxy in runtime Spring intersects the call, requests the factory to return the instance of the bean and invokes the method on that bean. The factory in its turn may lookup for "real" bean instance e.g. in HTTP request ("request" scope) or HTTP session ("session" scope) and/or create new instance if necessary. Late instantiation allows to initialize the scoped bean with "runtime" (scope) values, e.g. values from HTTP request/session which are obviously undefined when context was created. In particular "step"-scoped beans are bound to thread local (remember that steps are run in parallel for partitioning). So, scoped beans are dereferred when you call a method on them. Finally one can easily break this elegant Spring "ideology" by calling any method on scoped bean just after it is set to another bean (e.g. in the setter) :)
One thing to understand about lazy-initialization is that even though a bean
definition may be marked up as being lazy-initialized, if the lazy-initialized
bean is the dependency of a singleton bean that is not lazy-initialized, when the
ApplicationContext is eagerly pre-instantiating the singleton, it will have to
satisfy all of the singletons dependencies, one of which will be the
lazy-initialized bean!
Using a scope of Step is required in order to use late binding since the bean
cannot actually be instantiated until the Step starts, which allows the
attributes to be found. Because it is not part of the Spring container by
default, the scope must be added explicitly, either by using the batch namespace
or by including a bean definition explicitly for the StepScope (but not both):
<bean class="org.springframework.batch.core.scope.StepScope" />
Read here and here for more info
The scope="step" has nothing to do with Lazy initialization . It is use for late binding of parameters inside a "Step" .
the step scope is specifically for latebinding of job/step attributes and not really for late-binding of beans, meaning the spring bean context/factory will enhance stepscoped beans and look for attributes to set, e.g.
value="#{jobParameters[input.file.name]}