Spring Tutorial 19 - The Autowired Annotation
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- เผยแพร่เมื่อ 27 ส.ค. 2024
- In this tutorial, we'll use the Autowired annotation to wire up dependencies. We'll learn how to add dependencies by type and name. We'll also use Qualifiers to narrow down dependency contenders.
Thanks Koushik!! I have watched your 20 videos till now and I am so impressed with you. May God bless you!!
if you still get the NoUniqueBeanDefinitionException then add to your xml config.
I use following xml configuration code and it works.
thanx sir, I am 13'th person who appreciate your help
Very easy to understand, Thank you very much Koushik🙂
All the spring tutorials I am following & its very useful for new learners like me.Thanks a lot Kaushik for creating & uploading such a clean & easy to understand videos. :)
You can use aliases. Add this line to the spring.xml file:
@koushik, I really appreciate the hard work and effort you have put into creating these videos. You are surely getting my blessings and thanks and I am sure from so many other fortunate as well.
One more request from your, I am sure very busy, schedule, can you also provide tutorials of Spring MVC ?
Thanks again.
AJ
Please make you videos on new version of spring
@@Saurabh2816 3.2
First point: add in your xml; second point: just link Bean name instead of field will work
For people with error: (expected single matching bean but found 3 (or 4): ... ), update your pom.xml with this:
org.springframework
spring
2.5.6
for:
org.springframework
spring-core
4.1.4.RELEASE
org.springframework
spring-context
4.1.4.RELEASE
notice the
(spring-core in )
and
(spring-context in )
(stackoverflow.com/questions/23813369/spring-java-error-namespace-element-annotation-config-on-jdk-1-5-and-high/29647933#29647933)
(stackoverflow.com/questions/20894695/spring-configuration-xml-schema-with-or-without-version)
(mvnrepository.com/artifact/org.springframework/spring-orm/4.1.4.RELEASE)
I too face same issue, am using spring-context-5.2.9.jar version, spring-core-5.2.9.jar version. if you know any solution , please share
I have added this line in spring.xml under bean tag . Now it is working as expected. And removed bean tag of class org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor
sound of this expensive bike or car always catches my attention :D
If you are getting the IllegalArgumentException after adding the then upgrade your version of spring to the latest one / one which is compatible with your JDK
Yes, something like this should work:
If you are having problems with the annotations config element, you must make sure that you provide the right spring-context strings in your schemaLocation part of the bean defintions tag.
XML Namespace might have changed for spring 4.1.5. This is the latest one
Vamshi Krishna Specifically without the doctype that Koushik uses, I would like to add. Apparently no longer necessary.
Thanks Vamshi Krishna !
thanks
it worked
Awesome:)Well presented/summarized from spring io docs:)I 'm kind of lazy who don't read the whole documentation.But you made it so simple and tried max to cover from docs
Hi Koushik, Thank you for these great tutorials. I have notice some thing when I follow your tutorial. It looks like the AutowiredAnnotationBeanPostProcessor is actually matching the parameter name instead of the member variable name.
changing the member variable to a different name actually runs without any problem. even changing the setter method name runs without any problem. Only when I change the parameter name it actually throws the exception.
to illustrate.
in xml file
in Code Cicle.java
changing the member variable name from circle to circle1 did not break the program.
I went ahead and change the setter as well
public void setCentre1(Point centre) // not "1" prefixed But still the program runs
only when I change the parameter name it failed
public void setCentre(Point centre1) // look at the parameter name is centre1, this time I got the BeanCreationException.
I was expecting the exception in the previous cases (when member variable name didn't match or the setter Method name didn't match).
I am using spring Version 4.1.3
Banugoban Kones Yes, since 2.5 aka ever since annotations were supported: docs.spring.io/spring/docs/current/javadoc-api/org/springframework/beans/factory/annotation/Autowired.html
"Config methods[..]each of those arguments will be autowired with a matching bean in the Spring container. Bean property setter methods are effectively just a special case of such a general config method."
This will easily lead to confusion if you try to autowire and do a rename refactoring on the member variable in the process. That will (by default in Eclipse) not rename the arguments of the setters. It's best practice to have those match with the member variables. Therefore this problem can be avoided by adhering to (and making your IDE adhere to) the practice.
This makes sense as the member variable in the class is private.
Add this to resolve placeholders with $ interpretations.
You can give the @Autowired annotation on setter method or the member variable directly , What Kaushik has mentioned applicable to member variable , if you are giving the annotation to setter function then the setter function parameter is cross checked not the variable name
I get this error: Could not autowire method: public void com.mypackage.Circle.setCenter(com.techsharp.Point); nested exception is org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type [com.mypackage.Point] is defined: expected single matching bean but found 3: pointA,pointB,pointC. I have to set Primary bean in the xml in order to make to work... I still want to know why qualifier is not working....
Hi. You can put in the spring.xml file
Thanks Man..Worked for me
It works with " "
Why is that required?
just put it anywhere inside the main beans tag.
hi guys, i was getting the same erros about @qualifier but when i defined PostProcessors to it worked.
Thanks a lot it worked for me as well
But i am yet to understand the issue why it was unable to run the same without adding it although in the tutorials they haven't added anything like this!
This is work for me.
@@demigod6190 work for me to ffff something weird stuff istn it
Great tutorials! thank you very much!
Hello all, I was getting the error - the @Qualifier annotation is disallowed in this location. I was unable to locate the fix to this error after intensive search.
I was using all .jar files below 3.0 version. After changing the jar files to 3.0 and above version, the error got fixed. Hope this would be helpful to anyone out there facing this issue.
+Manasa Mattur We really appreciate your help. Thank you.
It worked
autowire firstly find the type, then find the first matched bean to wire.
Would any version of Spring not work with Eclipse Indigo? As while setting up the Xml namespace for @Required annotation, i got an error and am unable to resolve it. Help me urgently.
Hi everyone,
I have a problem. Everytime I paste to my xml file, the java.lang.IllegalArgumentException is thrown. My code doesn't throw an exception without but then I can't use annotations.
Same problem here ..
@@James5Sapphire update JDK and use most recent spring version
Okey, but if I have specified more than just one variable in class and some of them are the same type and some of them not, will the autowiring work or it would be to complex to it ?
is autowire annotation work when we are initializing the IOC container with Beanfacory interface?. like
BeanFactory apc=new XmlBeanFactory(new ClassPathResource("Spring-context.xml"));
in my case it only working with applicationcontaxt implementation.
Thanks a lot Koushik!
How to find namespaces if you haven't added JARS manually but using maven?
Hi,
I discovered that you can also use an alias instead of changing the name of the bean when using @Autowired . So instead of changing the name of the bean from "pointA" to "center" so that Autowired finds the name, you can also leave the bean name set to "pointA" and also create an alias.
Thanks again for the very good tutorials. Can you also provide tutorials of Spring MVC ?
Hello I get a TypeMismatchException setting the centre of the Circle if I keep
Instead of
Before @Autowire the property file was working fine.
Does @Autowired compare the name of the bean in the xml to the member variable itself, or the name of the argument in the setter method?
Ok, sorry, that q is already answered below by Banugoban Kones. This makes sense as the member variable is private.
if you getting error like this :
Error creating bean with name 'pointA' defined in class path resource [applicationContext.xml]: Initialization of bean failed; nested exception is org.springframework.beans.TypeMismatchException: Failed to convert property value of type 'java.lang.String' to required type 'int' for property 'x'; nested exception is java.lang.NumberFormatException: For input string: "${pointA.pointX}"
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'pointA' defined in class path resource [applicationContext.xml]: Initialization of bean failed; nested exception is ...bla bla
than add the this cod lines
It works fine without the tag in xml
Can someone tell me that what is the need for @Qualifier annotation? Why Spring cannot use some annotation to just link the property ("circle" in this case) with the bean defined in the properties file ("pointA" in this case)? I found this unessential an just an overhead until there is some valid use of @Qualifier annotation.
Qualifier is useful when you have multiple implementation of same interface and you are injecting the interface in different service/component and each of those service/component requires different implementation. For example you are generating HTML and XML representation of an object model say - Person, then you define an interface Representation with method write(Person person) and then HtmlRepresentation implementation of Representation will generate HTMl of Person and XmlRepresentation implementation of Representation will generate XML for Person. So keeping interface (write(Person person)) same you can have different representation based on context for example in this case HTML in case of web and XML in case of API. If you have only one implementation of interface, Qualifier is not required. Hope this helps
Jay, short and sweet explanation! You have been always my inspiration for J2EE. Looks like you have worked a lot in Spring. What all modules have you worked on? I have started learning.
Glad that explanation helped you. Yes I've been working on Spring for quite a sometime now. Worked with many core, web, ws, data, security etc. Spring is great framework developed by developers for developers.
No need to add the bean for Qualifier annotation ? In the video it worked without adding the bean for Qualifier !!
Nicely explained..
Hi Koushik, Thanks for video uploads !!!
I was trying to use @Autowired with @Qualifier on setter "public void setCentre(Point centre)" method but its giving error of "The annotation @Qualifier is disallowed for this location". I tried googling to find answer and stumble upon a link saying " @Qualifier is only allowed on fields and attributes not methods (you need to put it on the method attribute)." Does this implementation spring version specific? or Did i miss anything?
or he could use syso + ctrl + space for System.out.println();, but I guess he wants to show us how things get done step by step. This a very good tutorial ...
why did you removed the xml doctype tag?
why cant you import the packages before ?
Koushik, can we have multiple qualifiers to single bean?
To Comment
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To Format the code
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To import the related dependencies
ctrl+shift+O
In the Circle class, when I add @Autowired and @Qualifier("circleRelated"). Eclipse shows an error saying:" The annotation @Qualifier is disallowed for this location". This happens even when I have the imports such as "...annotation.Autowired and ...annotation.Qualifier. Does anyone else no how to resolve this?
This is the error I get: The annotation @Qualifier is disallowed for this location
Near this snippet of code:
@Autowired
@Qualifier("circleRelated")
public void setCenter(Point center) {
this.center = center;
}
These are my import in the circle class:
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
Michael Jones
Try to copy from here:
www.tutorialspoint.com/spring/spring_annotation_based_configuration.htm
Awesome.. I am also looking out for some web application example using JTA MAVEN
Can you explain it without XML file
Hey Koushik, first of all, thank you very much for posting these videos, really useful! My question is, are those post processor bean declarations not required in Spring 3.1? I am using Spring 3.1, and my code works (@Required and @Autowired) without those bean post processor declarations!
there might be a chance you have defined a tag in your spring xml file. If you have declared this tag you don't need to declare post processors explicitly.
can a bean have multiple qualifier
Ankit Rathore No. The last qualifier overwrites all the others. But you can give a bean as many aliases (see earlier video) as you want and those actually match with the Qualifier annotation, as well (as per Spring version 4.2.0), so that's essentially the same as multiple qualifiers.
thanks..
i tried to use qualified annotation. But it is not detecting. I'm still getting Error creating bean with name 'circle': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire method: public void org.sri.javabrains.Circle.setCenter(org.sri.javabrains.Point); nested exception.
Can u plz help me to solve this problem.
Thanks a lot for the vedios
Where and how can I find current xml namespaces?
Found them... these worked for me:
In some cases...
In my case it's ctrl+shift+c
ctrl shift - collapse everything
Koush
V8 automatic @ 00:29
ctrl+shift+/ - conversion to comment
Please
This also works
Comment/Uncomment = Ctrl+Shift+C
Very slow tutorial and dragged topics