I have written a camel component by extending DefaultComponent and also have the associative classes implemetation for endpoint, consumer, producer. My producer is extending the camel DefaultProducer and I want to inject a spring bean inside this class, so that whenever a route will be executed like
<route id="myRoute"><from uri="file://inbox"/><to uri="myComp://outbox"/>
I will be able to get the file from the file system and store it into database. For storing the file into the DB I have a service class instantiated by the spring container, but whenever I inject that bean into MyProducer we are getting null.
I recongnized the problem was not about Camel, it is related to the spring and I was injecting the bean in a wrong way. I resolved the problem by implementing the ApplicationContextAware interface into my helper class and storing the spring context as static variable and with the help of this helper class I am able to get spring bean inside MyProducer class. Thanks for spring ApplicationContextAware interface.
Related
In my sample spring boot application, i have added a dependency of a custom jar. My sample application has a support for web and jpa.
The jar which i've created contains a Spring MVC controller. Below is the sample code
#Controller
public class StartStopDefaultMessageListenerContainerController {
#Autowired(required=false)
private Map<String, DefaultMessageListenerContainer> messageListeners;
I haven't manually created a bean instance of this controller anywhere in my code.
Problem - When i start my spring boot application by running the main class, i get an error in console that prob while autowiring DefaultMessageListenerContainer.
My question here is, even though this class StartStopDefaultMessageListenerContainerController is just present in the classpath, it's bean shouldn't be created and autowiring should not happen. But spring boot is scanning the class automatically and then it tries to autowire the fields.
Is this the normal behavior of spring and is there anyway i can avoid this?
If the StartStopDefaultMessageListenerContainerController class is part of component scanning by spring container, Yes spring tries to instantiate and resolve all dependencies.
Here your problem is #Autowired on collection. Spring docs says,
Beans that are themselves defined as a collection or map type cannot be injected through #Autowired, because type matching is not properly applicable to them. Use #Resource for such beans, referring to the specific collection or map bean by unique name.
And also Refer inject-empty-map-via-spring
I have a spring application where in some cases I need to create an object at runtime, as opposed to a spring injected bean. This object should be created with properties that come from the application context however. If this object is not spring-injected, how can I still take advantage of IoC? Should I make these object properties static and inject them into a bean via non-static setters?
You can still inject properties for object which is not created by spring.
To do that you should use #Configurable annotation. And you should enable LoadTimeWeaving or CompileTimeWeaving. But I think that can be overkill for your situation.
I'm new to Spring and I'm confused about something basic. Are the classes that are stereotyped (Service, Controller, Repository) treated as beans? I'm confused as to when you actually need to annotate/configure something as a bean and when you don't. Is it for the classes that aren't stereotyped?
Thanks!
From spring documentation:
In Spring, the objects that form the backbone of your application and
that are managed by the Spring IoC container are called beans. A bean
is an object that is instantiated, assembled, and otherwise managed by
a Spring IoC container. Otherwise, a bean is simply one of many
objects in your application. Beans, and the dependencies among them,
are reflected in the configuration metadata used by a container.
Service, Controller, Repository are managed by the Spring IoC container, so they are called beans. You annotate a class as #Serivice, #Controller, #Repository, or more in general #Component when you want spring to manage it: spring will manage the instance of annotated class in regard of the scope you select (not all these scope are always available):
singleton – Return a single bean instance per Spring IoC container
prototype – Return a new bean instance each time when requested
request – Return a single bean instance per HTTP request
session – Return a single bean instance per HTTP session
globalSession – Return a single bean instance per global HTTP
session
In XML file in spring we have two bean with different id but same class. They have the same properties offcourse. Now I have InitializingBean interface and in afterPropertySet() I am just printing the value of properties.
Its printing the values two times for me?
According Spring Documentation:
afterPropertySet()
Invoked by a BeanFactory after it has set all bean properties supplied (and satisfied BeanFactoryAware and ApplicationContextAware).
So the short answer on your question is: yes
Spring doesn't manipulate classes or object. Spring manipulates Bean Entity. It is the simplest object manipulated by Spring IOC. Bean has additional behaivior rules introduced by Spring.
If you create two beans for example with Singleton scope and not Lazy initializated Spring creates two instances of your class.
Probably you are calling this Class also invoking a Test or by launching a Integration test like this . check the breakpoints , if you are using SpringRunner, try to mock the component
I have a question about spring and struts.
Currently I have spring injecting my struts action classes for me.
I was experimenting and trying to get Spring to inject my Struts action classes
for me using autowiring.
I have my spring applicationContext config file scanning the base package that the
action class is in using context:component-scan base-package="my.package",
and im using #Component annotation at the action classes class level.
Im also using #Qualifier("myActionClass") at the same action classes class level.
Im not configuring the action class as a Spring bean in applicationContext.
Then in my struts.xml config file, while configuring my action class, instead of giving the fully qualified package and class name, I use the #Qualifier annotation name "myActionClass".
This doesnt work though.
If in my applicationContext config file, configure my action class as a spring bean, get rid of the #Component and #Qualifier annotation on the action class, and in struts.xml, put the action classes Spring bean id for the class, then Spring injects my action class for me and everything is dandy. Only, this isnt using Autowiring the action class, and thats what I was testing.
Anyone know if autowiring using context:component-scan base-package
to scan your packages for your action classes so you dont have to configure them in applicationContext is possible?
Everything is explained in Spring documentation: Apache Struts 1.x and 2.x.
I am not sure whether you are using Struts 1 or 2. For Struts 1 you had to add Spring plugin to Struts configuration (I know it works). In Struts 2 all actions are created by Spring hence they are fully capable of Spring injection like all other beans.
Struts 2 seems to rely on there being a spring bean with the same spring bean-name matching the action class name (full name with package). You can specify the bean name in the #Component annotation, and it's also possible to make a global user-defined bean naming strategy so you can avoid adding this information to all your beans