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Article: What's New in Spring 2.5: Part 1: Annotation-Based Configuration

| by Geoffrey Wiseman Follow 0 Followers on Nov 19, 2007. Estimated reading time: 1 minute |

November 19th 2007 was a big day for the Spring Framework.  Spring 2.5 was released, Interface21 has become SpringSource and InfoQ has published the first article in a series of articles by Mark Fisher of SpringSource on the new features:  What's New in Spring 2.5: Part 1: Annotation-Based Configuration.

Describing the series of articles, Mark Fisher wrote:

The newly released Spring 2.5 continues this trend by offering further simplifications and powerful new features especially for those who are using Java 5 or greater. These features include annotation-driven dependency injection, auto-detection of Spring components on the classpath using annotations rather than XML for metadata, annotation support for lifecycle methods, a new web controller model for mapping requests to annotated methods, support for Junit 4 in the test framework, new additions to the Spring XML namespaces, and more.

This article is the first of a three-part series exploring these new features. The current article will focus on simplified configuration and new annotation-based functionality in the core of the Spring application context. The second article will cover new features available in the web-tier, and the final article will highlight additional features available for integration and testing.

If you're currently using the Spring Framework, this is a good opportunity to read about the new features and decide if there's a compelling reason to upgrade.  If you're not using the Spring Framework, but considering it, this is a good opportunity to learn about some of the new features that may make your decision easier, or harder.  Either way, the Spring Framework is a big part of how many people assemble their Java enterprise applications and Mark Fisher will help guide you through the new features in this article and the two parts yet to come.

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Missing/hidden XML by Matt Raible

There seems to be a fair amount of missing or hidden XML in this article. If you look at the HTML source, you'll see where some XML has not been properly escaped.

Re: Missing/hidden XML by Mark Fisher

Matt,

You are right. Someone must have edited this recently, because the XML was showing up properly before. I just sent a mail to the editor.

Thanks,
Mark

Re: Missing/hidden XML by Diana Baciu

Hi Matt, Mark

The XML has been fixed now.

Best
Diana

Good Stuff by Ray Krueger

I am really looking forward to using these new features, great job guys.

By the way Mark, your sudden and unexplained use of the p: namespace might freak people out. In your explanation of the lifecycle annotations you declare the datasource using the p: namespace trick from blog.interface21.com/main/2006/11/25/xml-syntax... Unfortunately, many people probably aren't aware of this feature and it isn't actually mentioned in the article.

Grate Guice alternative by Thom Nichols

This is great -- I always liked the annotation-driven style of Guice but didn't want to abandon Spring just for that. Hooray for less XML!

Re: Good Stuff by Mark Fisher

Ray,

Thanks for pointing out that blog for the 'p' namespace. Hopefully that will serve as a 'footnote' now for anyone who may be confused by its usage. Those examples are taken directly from the PetClinic application by the way.

Thanks,
Mark

Annotations vs. XML by Geoffrey Wiseman

I have to admit, I'm content to use XML for wiring, myself -- although perhaps when I try the annotations, I'll discover more advantages than I expect. I seem to be in the minority here.

That said, I was more impressed by the features here than I expected to be, so next time I start some Spring config., I might give this a try.

Sorry about the XML; that might have been my fault, I changed some metadata after the initial publishing, and there are some quirks in the publishing process that Diana's better at handling. ;)

I'm looking forward to the next two parts of the article.

Re: Annotations vs. XML by Rod Johnson

Geoffrey
I have to admit, I'm content to use XML for wiring, myself -- although perhaps when I try the annotations, I'll discover more advantages than I expect. I seem to be in the minority here.

The goal of Spring is to be the ultimate component model. That component model can be configured in different ways. There is no perfect one size fits all approach to configuration. Different contributions are merged together by the container. Certainly, annotations have an important place. However, my experience in practice (long predating my creation of Spring) has been that you need to externalize significant parts of your configuration from Java code.

The annotation support in Spring 2.5 is very slick and definitely makes Spring a better product. You can mix and match annotation-driven and XML (and other) configuration so that you can use the appropriate solution for each problem. I'm proud that each version of Spring has made applications easier to build.

I recently presented on Configuring the Spring Container at QCon San Francisco, discussing alternative configuration options and best practices. The slides are available as PDF.

Re: Annotations vs. XML by Jörg Gottschling

The annotation @Resource is a little confusing in the context of spring. As I saw it I first thought it will be used for ressources and not for beans. Like that:

@Ressource("file:out/example.txt")
public void setOutput(Ressource ressource) {...}

Re: Annotations vs. XML by Rod Johnson

Jorg

I agree that @Resource is a poor name for the annotation, but we didn't choose it...

Rgds
Rod

lament the passing of design and OO programming by James Richardson

as now i can turn everything into a FactoryBeanImpl.

@Bonkers(Retention.FORALLTIME)
afterPropertiesSet()

Great Job by Khaled Habiburahman

Great Job, keep it up

Thanks

Re: Missing/hidden XML by mohan raj

Good Artical...

Re: Great Job by mohan raj

Of course...Great

the 2nd part and 3rd part by Nantian Lotus

Good material. But where can I find the 2nd part and 3rd part of this series.
Thanks.

Re: Good Stuff by Darryl Pentz

Not to mention how it's never mentioned how to actually create an instance of the object that is injected by Spring. We see the annotated class, and the <bean.../> configuration XML, but no idea how to construct an instance of the annotated class. Does it appear as if by magic? Is it just me, but why are there no examples of this. Everything is just assumed to originate as some implicit class of the Spring framework, like a controller or some such.

I'd like to use this uber-magic of Spring, but how do I create instances of my own 'controller-type' classes automagically injected by Spring. Is this a state secret perhaps? Sorry, just frustrated by the lack of examples, clearly.</bean.../>

Re: the 2nd part and 3rd part by Lou Sacco

Agreed...this would be very useful.

Re: Good Stuff by Archie Cobbs

Darryl Pentz writes:

Not to mention how it's never mentioned how to actually create an instance of the object that is injected by Spring. We see the annotated class, and the configuration XML, but no idea how to construct an instance of the annotated class. Does it appear as if by magic?


I had the same question the first time I read this article (too quickly). The answer lies in the "Auto-Detection of Spring Components". The key "magic" is this tag:


<context:component-scan ... />


which causes Spring to automatically go hunting through your JARs looking for specially-annotated classes. When it finds them, it auto-constructs instances and adds them to your application context. The net effect is a purely annotation-driven (zero XML) way to add and configure individual beans.

2nd and 3rd parts by Gregor Morrison

Mark, great work, are parts 2 and 3 available yet?

Re: 2nd and 3rd parts by Mohammad Naqvi

Hey Greg, Did you hear anything about the 2nd and 3rd parts yet?

the last part by john wang

"While all Spring-managed objects are treated as singleton instances by default, it is sometimes necessary to specify an alternate "scope" for an object. "

I believe with the @PostConstruct @PreDestroy, the default should change to "request" or "prototype", not singleton any more... otherwise it is very possibly not thread-safe....

And is there any plan to support more lifecycle/AOP like annoations? like @PreInvoke @PostInvoke....

Re: the last part by Lukasz Budnik

I wrote a series of posts called "Spring for JEE developers"

I describe some of Spring 2.5 new features like partial implementations of JSR 220 and JSR 250.

If someone is interested here they are:

jee-bpel-soa.blogspot.com/2008/11/spring-for-je...
jee-bpel-soa.blogspot.com/2008/11/spring-for-je...
jee-bpel-soa.blogspot.com/2008/11/spring-for-je...

best regards

Re: 2nd and 3rd parts by Johan Pelgrim

Here's the second part (haven't found the third part yet)

www.infoq.com/articles/spring-2.5-ii-spring-mvc

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