If you've never used Spring, I'd say that learning either one will suit your purposes. The majority of Spring 2.5 carries over to 3.0, so it's not wasted.
The books and tutorials haven't kept up with Spring 3.0. Another change between versions was the purchase of Spring by VMWare. They've separated paid support from open source, so it's hard to tell what the future will be for non-paying customers.
@Dolph, in the simplest term, think of Spring as your application framework at the highest degree. This "framework" provides several "component buckets" where you can easily plug in different types of implementations. For example, for ORM, you may choose to use Hibernate over JPA or TopLink, for front end, you may choose Wicket over Struts or SpringMVC, and so forth.
The whole beauty of this (besides all the goodies stated in other posts) is it allows you easily swap out any of these implementations easily in the future. So, you can essentially rip out Hibernate one day and replace with TopLink, and it will never cause ripple effect to other components.
Another beauty of using Spring is your code becomes less clutter and has loose dependencies with other classes because you spend less time creating new objects yourself, Spring handles that for you. That said, you will quickly realize how easy for you to test your code because your API to be tested becomes very atomic. This is one primary reason why folks get discouraged in writing testcases, because they quickly realize that in order for them to test one API, they have to construct whole lot of things just to test that. Because of that, the whole process is brittle, imagine if you change that API, you need to reconstruct everything before testing it again.
Annotations in Java programing language is a special form of metadata that can be embedded in Java source code. The use of annotations in Java language is introduced in Java 5.0 ie Java 5 provides metdata support at language level.
In Spring, XML based configurations is the most popular configuration style.. Then annotation based configuration style came which enables users to configure beans inside the java source file itself. Spring framework provides different custom java5+ annotations. These annotations can be used in transactional demarcation, aop, JMX etc. There are core Spring Annotations, Spring MVC Annotations, AspectJ Annotations, JSR-250 Annotations, Testing Annotations etc. Both xml based configurations and Annotations have pros and cons. I would suggest mixing the two.
The custom Spring annotations are framework specific. But you can write your own annotations also.
The Core container module is the most important module which handles the basic principle of Dependency Injection and it's used in all other modules in the framework. Spring MVC is only a web MVC framework built on Spring's core functionality.
I found Spring in Action to be an excellent guide
You could check out Spring in Action. It has a chapter about messaging using JMS from Spring which I found helpful.
"Spring in Action", "Pro Spring", and "Spring Recipes" are the three that I'd recommend to anyone.
If you've never used Spring, I'd say that learning either one will suit your purposes. The majority of Spring 2.5 carries over to 3.0, so it's not wasted.
The books and tutorials haven't kept up with Spring 3.0. Another change between versions was the purchase of Spring by VMWare. They've separated paid support from open source, so it's hard to tell what the future will be for non-paying customers.
@Dolph, in the simplest term, think of Spring as your application framework at the highest degree. This "framework" provides several "component buckets" where you can easily plug in different types of implementations. For example, for ORM, you may choose to use Hibernate over JPA or TopLink, for front end, you may choose Wicket over Struts or SpringMVC, and so forth.
The whole beauty of this (besides all the goodies stated in other posts) is it allows you easily swap out any of these implementations easily in the future. So, you can essentially rip out Hibernate one day and replace with TopLink, and it will never cause ripple effect to other components.
Another beauty of using Spring is your code becomes less clutter and has loose dependencies with other classes because you spend less time creating new objects yourself, Spring handles that for you. That said, you will quickly realize how easy for you to test your code because your API to be tested becomes very atomic. This is one primary reason why folks get discouraged in writing testcases, because they quickly realize that in order for them to test one API, they have to construct whole lot of things just to test that. Because of that, the whole process is brittle, imagine if you change that API, you need to reconstruct everything before testing it again.
Pro Spring book is good, mentioned by @JLBarros. I like Spring in Action very much. It is very very easy to read when I first got started with Spring. This is probably one reference book that I read from skin to skin.
Annotations in Java programing language is a special form of metadata that can be embedded in Java source code. The use of annotations in Java language is introduced in Java 5.0 ie Java 5 provides metdata support at language level.
In Spring, XML based configurations is the most popular configuration style.. Then annotation based configuration style came which enables users to configure beans inside the java source file itself. Spring framework provides different custom java5+ annotations. These annotations can be used in transactional demarcation, aop, JMX etc. There are core Spring Annotations, Spring MVC Annotations, AspectJ Annotations, JSR-250 Annotations, Testing Annotations etc. Both xml based configurations and Annotations have pros and cons. I would suggest mixing the two.
The custom Spring annotations are framework specific. But you can write your own annotations also.
The Core container module is the most important module which handles the basic principle of Dependency Injection and it's used in all other modules in the framework. Spring MVC is only a web MVC framework built on Spring's core functionality.
You can go through Spring documentation and books like Spring in Action and Spring Recipes to get a good idea about the framework.