I m a newbie & i m good at Struts framework. Today i tried a tutorial for Spring MVC Framework.
The example url that i tried following is as below:
http://static.springsource.org/docs/Spring-MVC-step-by-step/part6.html
I think they have made this tutorial much more complex especially near its end. I saw some errors mainly typos in part 5, part 6 of tutorial. I found Spring framework as not properly organized and how would we know what classes to extend especially when their names are so weird (pardon my language) e.g. AbstractTransactionalDataSourceSpringContextTests.
Overall i found that Spring is making things much more complex than it should be. I'm surprised why there is such a hype about Springs being very easy to learn.
any suggestion how to learn spring easily ? how to judge what to extend ? is there a quick reference or something?
The tutorial you have referred to covers all the layers of the application - data access, business logic and web. For someone who is looking to only get a feel of Spring MVC, which addresses concerns specific to the web layer of the application, this could be more information than required. Probably that is why you got the feeling that the tutorial is complex.
To answer your questions, Spring is easy to learn because the whole framework is designed to work with POJOs, instead of relying on special interfaces, abstract classes or such. Developers can write software as normal Java applications - interfaces, classes and enums and use Spring to wire the components up, without having to go out of the way to achieve the wiring. The tutorial you have referred to tries to explain things in a little bit more detail than experienced programmers would typically do in a real application, probably because the authors wanted the readers to get enough insight into how Spring works so that concepts are understood well.
In most applications (regardless of their size or nature), there is typically no need to extend Spring classes or to implement specialised classes. The Spring community is quite large and an even larger ecosystem of readily available components exists that integrate with Spring. It is therefore very rare that one has to implement a Spring component to achieve something. For example, let us take the example of the data access layer. Different teams like using different approaches to accessing databases. Some like raw JDBC, others like third-party ORMs like iBatis or Hibernate while some others like JPA. Spring distributions contain classes to support all these approaches. Similarly, lets say someone was looking to incorporate declarative transaction management in their application. Again, transaction management can be done in many different ways and a large number of transaction management products are available for people to use. Spring integration is available for most of these products, allowing teams to simply choose which product they want to use and configure it in their Spring application.
Recent Spring releases have mostly done away with extensive XML based configuration files, which being external to the Java code did make Spring application a bit cumbersome to understand. Many things can be done nowadays with annotations. For example,
#Controller
public class AuthenticationController
{
...
}
Indicates that AuthenticationController is a web MVC controller class. There are even ways to avoid using the Controller annotation and follow a convention-over-configuration approach to simplify coding even further.
A good and simple tutorial to Spring MVC is available at http://www.vaannila.com/spring/spring-mvc-tutorial-1.html. This tutorial uses XML based configuration for Spring beans instead of annotations but the concepts remain the same.
I have seen tutorial you follow , Its seems you have follow wrong one first , you first tried to simple one, Instead of tutorials you should go for book first
I recommend you two books to understand the power of Spring
spring in action and spring recipes.
For practical you can use STS a special ide for spring project development.Its have some predefined template you dont't need to write whole configuration yourself.
In starting just see simple tutorials like Spring mvc hello world , form controller than go for big ones
Spring is very cool , All the best.
Related
Spring is a popular framework, however I have difficulties to see in which situation the framework would actually help.
Currently I'm using the following:
* Tomcat
* Jersey
* Jackson
* Hibernate
Together this results in a Webservice, created by annotations, automatic JSON (un)marshalling and a comfortable Object/Relational Mapping.
So honestly at the moment I'm not missing anything, but I might just not know what great thing I'm missing... Could you help me out with this?
Thank you
Spring is a big framework providing a lot of functionality. It's hard to talk about advantages without knowing what functionality are you trying to use in the project.
Most probably you talk about Spring as an IoC container. It is very important part of Spring, but there is also AOP, transaction management, JDBC abstraction layer, authentication and authorization, testing and some more.
In a nutshell, Spring offers you uniform way to control dependencies between your objects. This is called inversion of control or dependency injection. Using it you can create pluggable, testable code that is easy to maintain.
In addition it gives you gazillion utility classes that just make life easier. For example, Hibernate is much easier to maintain via Spring facilities. It kind of brings together many different technologies under the same roof.
I am starting to learn the Spring Framework. I came across this link but I can't understand in which order to learn from these?
Can anybody help me out?
The order of the entries on that page isn't organized so that you can gradually learn the concepts.
I'd rather advise you to try and go through the official Spring documentation first and take a look at the samples that come together with Spring. It'll give you an idea of the possibilities. Also, don't forget to make sure that you understand what the Inversion of Control (IoC) pattern is and why it's useful.
Here's what I'd recommend to someone starting out with Spring and IoC:
You should first try to use Spring in a very simple command-line application (hello world style).
Create an application context in xml and load it from your main method
Define a bean and retrieve it from your freshly loaded application context
Try to add a second bean definition in the application context and play with the bean definitions
Learn how to inject beans in properties, in constructors, ...
Play with those for a while in order to get a good feeling of what Spring core actually does for you (the IoC container) and how it can help you to decouple components in your code
Once you have a clear understanding of that, you can move on and read about Spring annotations and how you can either use xml or annotations (or even combine both approaches) to wire up your beans
You should only start using Spring in a Web application after having played around enough with the above. Once you have all that under control, then it'll be time to discover more advanced stuff and other Spring portfolio projects such as Spring Security, Spring MVC, Spring AOP, ...
The following are nice to have on the desk:
- Spring Configuration Refcard
- Spring Annotations Refcard
In any case, have fun! :)
I suggest you to learn from a books
I use Spring Recipes Second Edition to learn spring, the books is very technical and explain a good concept about spring
I know the title may seem like apples & oranges, but hear me out... :)
I'm building the architecture of an MVC app and considering what to use for the core of the controller / services. This stack will also serve as a RESTful API which will be equally as important as the UI.
I'm narrowing down my stack to be built with either Grails or JAX-RS (at this point I've ruled out other options and am not super interested in expanding this list). Either way I'll be using Groovy, and my model and views will be virtually unaffected by this choice, so that further levels some of the differences between the two. Here are the pros/cons that I've been pondering and was wondering if anyone had any other inputs or caveat experiences.
Grails
I am not going to use a ton of the built-in Grails features (GSP/SiteMesh, Hibernate, nearly all plugins), so I'm concerned that Grails might be a bit heavy for my purposes
I'm concerned that I won't have enough control over my ability to handle the REST API since it is very view-centric
I've seen inconsistencies in the quality of plugins to the point where I'm not sure I consider them much of a 'pro'
I love the convention-over-configuration & edit-and-refresh, to the point where I'd probably want to wire up something similar if I go with JAX-RS
I like the grails command line for everything it streamlines, but I'm concerned that it might get in my way since I'm not using as much of the stack
I like the scaffolding but since I'm not using Hibernate or GSP/SiteMesh it might not mesh well
JAX-RS
JAX-RS is made for REST. This will make my RESTful API really a snap to implement as I have complete control
Groovy is an important part of what makes Grails shine, so I'll benefit from that even in JAX-RS
I love how JAX-RS doesn't automatically pull in a bunch of other things so I can have more control of what components are in/out
unfortunately since it doesn't pull in everything else anything that I end up needing will require more work, whereas Grails might have a plugin
the grails command line and scaffolding will be missed; perhaps Maven can fill some gaps
It seems like the capabilities of each for creating actions and routing are pretty similar (although the implementation styles are different). In fact there are other SO questions wish touch upon this so I'm not too concerned.
I wrote a small REST service prototype in several frameworks last year (namely Grails, Play!, Spring MVC, Jersey, Restlet). My feeling about Grails in this concern was that although Grails supports REST style architecture, it isn't really made for it. I don't want to get religious here, so if you only want to map resources to URLs and HTTP verbs your fine, but if you want to dig deeper into REST with tight control over return codes, location headers, etc. you might still be able to do it with Grails, but it is probably better supported in a pure REST framework.
Grails also comes with a lot of dependencies, which might not be a problem if you're starting on a green field, but can cause problems when you have to integrate it with existing legacy components or frameworks.
From the two used REST frameworks, I liked Jersey more, as it just worked in my case and the documentation was good (although a bit focused on Maven and Netbeans).
Yeah, it does seem heavy to build on a MVC framework when you're not going to use the model or the view. While the autowiring and simplified configuration is super nice, Grails would still be providing a lot of extra stuff that you don't need.
I'd personally take the lighter approach and leave Grails out, using any standalone libraries or writing custom code which provide the features that you do want. There's a number of container projects listed on the Groovy site, perhaps Spring or one of the alternatives would add some value to your architecture.
I love the concept of DI and loosely coupled system, a lot. However, I found tooling in Spring lacking at best. For example, it's hard to do "refactoring", e.g. to change a name of a bean declared in Spring. I'm new to Spring, so I would be missing something. There is no compiling time check etc.
My question is why do we want to use XML to store the configuration? IMO, the whole idea of Spring (IoC part) is to force certain creational pattern. In the world of gang-of-four patterns, design patterns are informative. Spring (and other DIs) on the other hand, provides very prescribed way how an application should be hooked up with individual components.
I have put Scala in the title as well as I'm learning it. How do you guys think to create a domain language (something like the actor library) for dependency ingestion. Writing the actual injection code in Scala itself, you get all the goodies and tooling that comes with it. Although application developers might as well bypass your framework, I would think it's relatively easy to standard, such as the main web site/app will only load components of certain pattern.
There's a good article on using Scala together with Spring and Hibernate here.
About your question: you actually can use annotations. It has some advantages. XML, in turn, is good beacause you don't need to recompile files, that contain your injection configs.
There is an ongoing debate if Scala needs DI. There are several ways to "do it yourself", but often this easy setup is sufficient:
//the class that needs injection
abstract class Foo {
val injectMe:String
def hello = println("Hello " + injectMe)
}
//The "binding module"
trait Binder {
def createFooInstance:Foo
}
object BinderImpl extends Binder {
trait FooInjector {
val injectMe = "DI!"
}
def createFooInstance:Foo = new Foo with FooInjector
}
//The client
val binder:Binder = getSomehowTheRightBinderImpl //one way would be a ServiceLoader
val foo = binder.createFooInstance
foo.hello
//--> Hello DI!
For other versions, look here for example.
I love the concept of DI and loosely
coupled system, a lot. However, I
found tooling in Spring lacking at
best. For example, it's hard to do
"refactoring", e.g. to change a name
of a bean declared in Spring. I'm new
to Spring, so I would be missing
something. There is no compiling time
check etc.
You need a smarter IDE. IntelliJ from JetBrains allows refactoring, renaming, etc. with full knowledge of your Spring configuration and your classes.
My question is why do we want to use
XML to store the configuration?
Why not? You have to put it somewhere. Now you have a choice: XML or annotations.
IMO,
the whole idea of Spring (IoC part) is
to force certain creational pattern.
In the world of gang-of-four patterns,
design patterns are informative.
ApplicationContext is nothing more than a big object factory/builder. That's a GoF pattern.
Spring (and other DIs) on the other
hand, provides very prescribed way how
an application should be hooked up
with individual components.
GoF is even more prescriptive: You have to build it into objects or externalize it into configuration. Spring externalizes it.
I have put Scala in the title as well
as I'm learning it. How do you guys
think to create a domain language
(something like the actor library) for
dependency ingestion.
You must mean "injection".
Writing the
actual injection code in Scala itself,
you get all the goodies and tooling
that comes with it.
Don't see what that will buy me over and above what Spring gives me now.
Although
application developers might as well
bypass your framework, I would think
it's relatively easy to standard, such
as the main web site/app will only
load components of certain pattern.
Sorry, I'm not buying your idea. I'd rather use Spring.
But there's no reason why you shouldn't try it and see if you can become more successful than Spring. Let us know how you do.
There are different approaches to DI in java, and not all of them are necessarily based on xml.
Spring
Spring provides a complete container implementation and integration with many services (transactions, jndi, persistence, datasources, mvc, scheduling,...) and can actually be better defined using java annotations.
Its popularity stems from the number of services that the platform integrates, other than DI (many people use it as an alternative to Java EE, which is actually following spring path starting from its 5 edition).
XML was the original choice for spring, because it was the de-facto java configuration standard when the framework came to be. Annotations is the popular choice right now.
As a personal aside, conceptually I'm not a huge fan of annotation-based DI, for me it creates a tight coupling of configuration and code, thus defeating the underlying original purpose of DI.
There are other DI implementation around that support alternative configuration declaration: AFAIK Google Guice is one of those allowing for programmatic configuration as well.
DI and Scala
There are alternative solutions for DI in scala, in addition to using the known java frameworks (which as far as I know integrate fairly well).
For me the most interesting that maintain a familiar approach to java is subcut.
It strikes a nice balance between google guice and one of the most well-known DI patterns allowed by the specific design of the scala language: the Cake Pattern. You can find many blog posts and videos about this pattern with a google search.
Another solution available in scala is using the Reader Monad, which is already an established pattern for dynamic configuration in Haskell and is explained fairly well in this video from NE Scala Symposium 2012 and in this video and related slides.
The latter choice goes with the warning that it involves a decent level of familiarity with the concept of Monads in general and in scala, and often aroused some debate around its conceptual complexity and practical usefulness. This related thread on the scala-debate ML can be quite useful to have a better grip on the subject.
i can't really comment on scala, but DI helps enforce loose coupling. It makes refactoring large apps soooo much easier. If you don't like a component, just swap it out. Need another implementation for a particular environment, easy just plug in a new component.
I agree! To me he way most people use Spring is a mild version of hell.
When you look at the standard Springified code there are interfaces everywhere, and you never really know what class is used to implement an interface. You have to look into some fantastic configuration to find that out. Easy read = not. To make this code surfable you need a very advanced IDE, like Intelly J.
How did we end up in this mess? I blame automated unit testing! If you want to connect mocks to each and every class you can not have dependencies. If it wasn't for unit testing we could probable do just as well without loose coupling, since we do not want the customer to replace single classes willy nilly in our Jars.
In Scala you can use patterns, like the "Cake Patten" to implement DI without a framework. You can also use structural typing to do this. The result is still messy compared to the original code.
Personally I think one should consider doing automated testing on modules instead of classes to escape this mess, and use DI to decouple entire modules. This strategy is by definition not unit testing. I think most of the logic lies in the actual connections between classes, so IMHO one will benefit more from module testing than unit testing.
I cannot agree that XML is problem in Java and Spring:
I use Spring and Java extensively without to much XML because most configuration is done with annotations (type and name is powerful contract) - it looks really nice. Only for 10% cases I use XML because it is easier to do it in XML than code special solution with factories / new classes / annotations. This approach was inspired by Guice and Spring from 3.0 implements its as JSR-330 (but even that I use Spring 2.5 with spring factory configured with JSR-330 annotations instead of default spring-specific #Autowired).
Probably scala can provide better syntax for developing in DI style and I'm looking at it now (pointed Cake Pattern).
I have looked at Spring MVC a few times briefly, and got the basic ideas. However whenever I look closely it seems to require you already know a whole load of 'core Spring'. The book I have for instance has a few hundred pages before it gets onto Spring MVC... which seems a lot to wade through. I'm used to being able to jump in, but there's so much bean-related stuff and XML, it just looks like a mass of data to consume.
Does it simplify if you put the time in, or is Spring just a much bigger framework than I thought? is it possible to learn this side of it in isolation?
#John Spring just a much bigger framework than I thought? - probably so, at least I thought so.
is it possible to learn this side of it in isolation? - Yes , here is a good way to learn your way http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/spring-web.html
And also I'd recommend you read a book manning spring in action 2nd edition, I also was learning spring from zero, and now I'm comfortable with it after reading this book, of course you have to refer to reference every now and then.
Here is where you can get basic info about MVC concept if you are not already familiar with(its in php, but important thing is point not syntax)
http://net.tutsplus.com/tutorials/other/mvc-for-noobs/
EDIT
If you want to see MVC in action, with examples or other spring uses use this repository https://src.springframework.org/svn/spring-samples to checkout some projects , you'll see mvc-basic, mvc-ajax ..etc this is really good resource , you can checkout projects with Tortoise SVN on windows or subeclipse from eclipse
At least you need to understand the core Spring - dependency injection, application context configuration and so on. It's actually not too complex, just a bit hard to start. For an experienced developer it might make sense to take a look at some sample app for the basic setup.
ps. I've got this sample project for JSF/Spring/JPA/Hibernate combination. Not Spring-MVC, but may be still helpful.
I myself am trying to learn Spring MVC from NetBeans official documentation from here:
http://netbeans.org/kb/docs/web/quickstart-webapps-spring.html
Coming from ASP.Net/C#, it feels like there are so many steps to do in that simple example.
The great thing about Spring is that you can pick and choose what you use. If you want to use Spring, you don't have to jump in head first, you can just try it out by, say, using the Dependency Injection features, or by using the JDBC Template stuff. My recommendation would be to start small, and see how you like it.
To use the Web MVC stuff, you will need to understand Dependency Injection for configuring your controllers. You can choose to use the older more flexible XML-style configuration, or you can use the newer Annotations. Or you can mix and match. Starting with XML would probably be best as it will help you understand how stuff is working (it'd be like learning C and C++ before Java). Then you can move to using Annotations. Personally, I use XML to instantiate all my beans. I use the #Autowire annotation to inject dependencies. This seems to be the sweet spot for most flexibility and ease of use.