Lately, one junior developer asked me this question:"is there difference between using #autowired annotation and using "autowire" in spring xml configuration?"
I am not able to give him an specific answer.Please help me.
No. Spring offers multiple way of wiring up components. Depending on your system build, some may offer more advantages over other.
Related
Remove locations attributes from #ConfigurationProperties
What are the alternatives?
I've been using it like this before.
#ConfigurationProperties(locations = "a.yml")
Same problem here: we have hundreds of configuration keys on several yaml files, each of them conveniently mapped to a pojo that we inject into our business logic beans.
The best thing I could do to upgrade to Spring Boot 1.5 and at the same time keep our production application running without much refactoring is described here: http://fabiomaffioletti.me/blog/2016/12/20/spring-configuration-properties-handle-deprecated-locations/
Or, if that does not work for you, you can try this way which is simpler even if requires more refactoring (remove the #ConfigurationProperties annotation): http://fabiomaffioletti.me/blog/2017/02/09/spring-configuration-properties-locations-deprecation-another-approach/
what's the easiest way to get the spring boot goodness but not try to autoconfigure all the things? For instance, to only run flyway with our already configured properties (some loaded via Consul + Spring Cloud), I was hoping I could do something like:
#Configuration
#Import({DataSourceAutoConfiguration.class, FlywayAutoConfiguration.class})
public class FlywaySetup {}
and have the main method just call SpringApplication.run(FlywaySetup.class)
The problem with this is it picks up all the Component Scan / crazy long list of other dependencies. Any way to specifically configure the dependencies (but still get the nicities of the framework)
If you run this app, it shouldn't use component scan at all. There's nothing that triggers component scan in spring boot besides #ComponentScan (that's available on #SpringBootApplication).
It would help if you could provide more accurate details rather than "crazy long list of other dependencies.". Running that FlywaySetup should only load those two configuration classes (important: these are not handled as auto-configuration anymore). If you have component scan, there's something else you're not showing.
You can exclude auto-configurations you don't need.
You may want to take a look at this SO answer to explore mechanism how to do that.
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.
On Spring #Autowired usage question most of the people answer they prefer not using configuration files, if possible. It seems like a good answer at the first glance.
However, once you have quite a big application which uses Spring IoC and autowires all the stuff using annotations #Autowired, #Service, etc. you must hit this problem: you no longer are able to keep track of your bean dependencies.
How do you deal with that?
Using SpringSource Tool Suite one can create graphs of dependencies on the basis of configuration files.
Is there any tool out there which does the same with #Autowired stuff? (I understand graphs would have to be created on runtime).
Implement BeanFactoryAware and cast the factory that is passed into setBeanFactory() to a DefaultListableBeanFactory. Then use DefaultListableBeanFactory.getBeanDefinitionNames() and DefaultListableBeanFactory.getDependenciesForBean() to generate the dependency graph.
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