Develop Reference

Spring JavaConfig equivalent of referring to beans by name

In Spring XML config, I can use the ref="bean_name" syntax to refer to a bean by ID or name.
<bean id="petStore" class="org.springframework.samples.jpetstore.services.PetStoreServiceImpl">
<property name="accountDao" ref="accountDao"/>
</bean>
Is there an equivalent way of achieving this in Java config, using the name attribute on the #Bean annotation? I've used the #Named annotation (javax.inject.Named) and have seen #Qualifier suggested elsewhere, but is a separate annotation really necessary if we already have a name attribute on the #Bean annotation?

#Qualifier is the correct thing to use here.
#Autowired
#Qualifier("bean_name")
private Beantype var;
And declaring your component
#Component(value = "bean_name")
public class Beantype {...}
At least that works for me.

how to inject parent class property with spring annotation

parent class is like this:
public class BaseDAO{
private DBRoute defaultDB;
public DBRoute getDefaultDB()
{
return this.defaultDB;
}
public void setDefaultDB(DBRoute defaultDB)
{
this.defaultDB = defaultDB;
}
}
I have create beans like below:
<bean id="adsConfigDB" class="net.flyingfat.common.dbroute.config.DBRoute">
<constructor-arg value="adsConfig" />
</bean>
<bean id="adsBizDateDB" class="net.flyingfat.common.dbroute.config.DBRoute">
<constructor-arg value="adsBizDate" />
</bean>
I want to inject superclass property defaultDB in subclass through byName, not byType, which is in subclass inject defaultDB using adsConfigDB or adsBizDateDB. Is there any way to do this with spring annotations? I already tried Autowired or Resource with constructor which doesn't work. By the way, I already know this can be done using XML.

#Qualifier annotation – This annotation is used to avoid conflicts in bean mapping and we need to provide the bean name that will be used for autowiring. This way we can avoid issues where multiple beans are defined for same type. This annotation usually works with the #Autowired annotation. For constructors with multiple arguments, we can use this annotation with the argument names in the method.
Your code will be like this..
#Autowired
#Qualifier("adsConfig")
private DBRoute defaultDB;

injecting beans into spring java config classes

I have a configuration class which uses the #Configuration annotation and also extends the RepositoryRestMvcConfiguration.
as part of the extended class, there are overridable methods that allow configuration of the bean recipes. one of which is configuring the conversion services available to the spring component.
I would like to inject some beans into a list that is iterated over and added as a conversion service through this overrided method, My configuration java class is defined below:
#Configuration
#EnableJpaRepositories(basePackages = "com.example.model.repositories")
public class DataConfig extends RepositoryRestMvcConfiguration {
List<Converter<?,?>> converters;
//get
//set
#Override
protected void configureConversionService(ConfigurableConversionService conversionService){
for(Converter converter : converter){
conversionService.addConverter(converter);
}
}
}
The following defines my converters that i wish to inject in the app-context.xml file
<beans>
<bean id="fooToBarConverter" class="com.example.model.converters.FooToBarConverter" />
<bean id="barToFooConverter" class="com.example.model.converters.BarToFooConverter" />
<util:list id="myConverters" value-type="org.springframework.core.convert.converter.Converter">
<ref bean="barToFooConverter"/>
<ref bean="fooToBarConverter" />
</util:list>
</beans>
Is there a better way of providing these converters through spring configuration or do i need to explicitly list them as output of a function contained within my configuration class like:
#Bean
public List<Converter<?,?> myConverters(){
Arrays.asList(new FooToBarConverter(), new BarToFooConverter());
}
Your help is highly appreciated.
P.S. since you are so good at spring, would you mind having a look at my spring-data-rest-mvc related question? please and thank you.

By default, any #Autowired (or #Resource) annotated Collection (or List, Set, etc) of a certain type will contain all beans of that type discovered in the context. You could add an #Autowired in your setter and let Spring injects your controller for you.
If you need a more fine-grained control over which converters should be configured and which one should not, maybe you should configure the ConversionService altogether instead.

How to override an imported resource using Spring #Configuration?

Is it possible to override imported resources using Spring annotation configuration?
The configuration class:
#Configuration
#ImportResource({"classpath:applicationContext.xml"})
public class CoreConfiguration {
#Resource(name = "classA")
private ClassA classA;
#Bean(name = "nameIWantToOverride")
private ClassB classB() {
return new ClassB("different setting");
}
}
The applicationContext.xml includes:
<bean name="classA" class="a.b.c.ClassA">
<property name="nameIWantToOverride" ref="classB" />
</bean>
If classA has a classB field but I want it to use the ClassB I define in my configuration class, is that possible? I tried switching the order but that didn't help. It seems XML takes precedence as when I run a simple test of instantiating the config, it never reaches the classB method. If I change the name so it doesn't match the bean in the xml file, then it does reach the classB method.
I've seen where it can work the other way: Can spring framework override Annotation-based configuration with XML-based configuration? but what about this direction? Since this is the newer way of doing things, I would think it you'd be able to do this.
What can I do to resolve this?
Edit: Updated with XML. Assume classA has multiple fields but I just want to replace the one.

You cannot override spring xml configuration using annotation.
Spring XML configuration always takes precedence to annotation configuration

Spring:autowired field is null

I need to wire external lib class to my bean,in order to use it as singleton.
.xml config:
<bean id="myBean" class="com.my.MyBean">
<property name="someLib" value="com.ExternalBean" />
</bean>
java bean:
#Service
public class MyBean {
#Autowired
private ExternalBean externalBean;
public void setExternalBean(ExternalBean externalBean) {
this.externalBean = externalBean;
}
Further I use wired variable externalBean in public method ,in order not to instantiate it in every method call.
Problem is it null.
Do I wire bean correctly?What is mistake.

You have to define the external class as a bean in order to make #Autowired work.
<bean id="externalBean" class="some.external.package.ExternalBean">
</bean>
<bean id="myBean" class="com.my.MyBean">
</bean>
Also, if you use #Autowired you don't need the setter for it.

loodakrawa is right. A second thing that can cause a problem is, that you have a xml bean declaration for myBean and additional annotated the bean with #Service. I guess this will cause trouble as soon as use enable component scan.

I think that the better ide ais to use context path scan:
<context:component-scan base-package="some.external.package">
</context:component-scan>
Make sure that all these classes are within the package. Then mark both classes with one of the Annotations (#Repository, #Service, #Component).
One of the benefits, no setter required.
P.S: If you re using scan base you don't need to declare class as bean, annotations are enough