Top X Jump Framework Annotations For Coffee Developers

There is no dubiousness that Spring framework is ane of the most pop Java frameworks as well as it has made the life of Java developer like shooting fish in a barrel past times providing approximately awesome features inward the final fifteen years. Spring uses dependency injection to configure as well as bind your application together but it doesn't strength you lot to implement ane of its interfaces. This allows you lot to code POJO (plain former Java objects), a bird alongside methods as well as attributes to practise most of your stuff. Then the questions come, how practise Spring provides those magical features if it doesn't inquire you lot to implement their interface, good they purpose annotations as well as many of them. You volition divulge approximately of the most mutual annotations inward this article, which is must for a Java developer to move alongside Spring.

I convey been using Spring from Spring 2.0 when everything was configured using XML, I slow moved to the annotation-driven configuration as well as and then establish my means towards Java based configuration.

What this proves is that Spring is constantly evolving as well as you lot convey to conk along upwards alongside its mensuration to conk along yourself up-to-date as well as knowing approximately essential Spring annotations volition for certain assistance inward your journeying of Spring.

If you lot convey been coding Java for a duo of months as well as then you lot may convey come upwards across at to the lowest degree of the annotations. The type which starts alongside "@" like @Override, perchance the most pop Java annotations ever. This prissy lilliputian metadata tin practise wonders inward price of improving code character as well as reducing the run a jeopardy of errors.

Ever since annotations were introduced inward JDK 1.5 they convey completely changed the Java landscape alongside to a greater extent than as well as to a greater extent than framework adopting them to render services as well as features as well as Spring is no different.

They brand heavy purpose of Annotations to render features you lot beloved e.g. automatically detecting beans, creating their instances as well as injecting them to the objects who involve them. Btw, if you lot are novel to Spring as well as then I advise you lot banking concern jibe a comprehensive course of teaching like Spring Framework five Beginner to Guru, which volition non solely learn you lot these annotations but every bit good other jump fundamentals you lot involve to know to move effectively alongside Spring.

Spring Core Annotations for Java developers

Since annotations are providing the interface betwixt Java as well as Spring, it's of import for a Java developer to hold out familiar alongside the essential interface as well as sympathise what they practise as well as how to purpose them. In this article, I'll portion approximately of the essential Spring annotations which I intend a Java Spring developers should know.


@Configuration
This Spring annotation marks a bird every bit a source of edible bean definitions as well as it's ane of the essential annotations if you lot are using Java-based configuration.

In before days, nosotros purpose an XML file to declare edible bean but at ane time you lot don't involve to practise that, you lot tin practise classes as well as convey methods which tin render Spring bean.


@ComponentScan
This Spring annotation instructs Spring to scan the parcel for all the @Configuration classes, which contains Spring edible bean definition inward Java-based configuration.


@Bean
This Spring essence annotation indicates that a method produces a edible bean to hold out managed past times the Spring container. This is ordinarily used inward the classes which are annotated alongside @Configuration annotation on the Java-based configuration inward Spring.

Here is an instance of @Configuration as well as @Bean annotation inward Spring inspired by Spring Framework Master Class course on Udemy:

@Configuration public class BookStoreConfig {  @Bean public BookStoreService bookStoreService() { return new BookStoreServiceImpl(); } }

In this example, nosotros convey annotated BookStoreConfig bird alongside @Configuration to signal that it contains edible bean definitions. And, where are those edible bean definitions? Well, the methods which are annotated alongside @Bean annotation. In this example, the bookStoreService() method render a Spring bean.  You tin every bit good check Spring Framework five Beginner to Guru for to a greater extent than examples.

@Component
This is approximately other basic Spring annotation which tin plough your bird into a Spring edible bean at the auto-scan time. In general, non all the bird you lot practise volition hold out Spring edible bean inward your projection but if a bird depends upon approximately other bird as well as you lot desire Spring to autowire that dependency as well as then you lot tin annotate the bird with @Component annotation.

One of the most pop examples of a @Component annotation is @Controller classes which human activeness a Spring MVC controller as well as handles HTTP requests. They are automatically detected past times Spring using annotation-based configuration as well as classpath scanning.

Again, this is a bird story annotation as well as hither is an example, inspired past times my favorite Spring book, Spring inward Action past times Craig Walls:

@Component public class MangoShake implements Dessert{ .....   }

Since this bird is annotated alongside @Component, they volition hold out picked upwards during component-scanning as well as created every bit a edible bean inward the Spring application context. Then Spring tin purpose that reference to autowire whatever dependency which is looking for a Dessert object.


@Service
Similar to @Controller annotation used inward Spring MVC, @Service is every bit good a specialization of the @Component annotation which has no encapsulated state. You tin farther read my article, difference betwixt @Service as well as @Controller annotations inward Spring to larn to a greater extent than nearly it.

@Autowired
This Spring annotation instructs Spring’s dependency injection to wire an appropriate edible bean into the marked bird member.

Here is approximately other instance from classic Spring inward Action book:

@Autowired public void setDessert(Dessert sweet){ this.dessert = sweet; }

When Spring volition come across this method, it volition endeavor to divulge out a Spring edible bean alongside type Dessert as well as tin telephone telephone this method to inject the dependency.  See Spring inward Action, inward which nosotros convey a setDessert() method which uses @Autowired for auto-wiring dependency.

Now, if nosotros convey to a greater extent than than ane Dessert edible bean inward Spring application context as well as then Spring volition confuse as well as non able to inject whatever dependency. Instead, it volition throw NoUniqueBeanDefinitionException.

You tin resolve that ambiguity past times using @Qualifier annotation every bit shown below:

@AutoWired @Qualifier("iceCream") public void setDessert(Dessert dessert){ this.dessert = dessert;  }

This code volition instruct Spring to inject the edible bean alongside id "iceCream" should hold out injected into this method.



@Value
This Core jump annotation indicates a default value appear for the acre or parameter, typically something similar “#{systemProperties.myProp}”

Here are a duo of examples of @value annotation inward spring:

@Value("NA") private String name

This code injects default String value to holding name, but instead of a simply obviously string, you lot tin every bit good inject values from the holding file as well as organisation properties. See Spring Framework five Beginner to Guru for to a greater extent than examples.

@Required
This annotation tin hold out used to specify a mandatory dependency. It tin fifty-fifty neglect the configuration if the dependency cannot hold out injected.

For example, you lot tin annotate a method alongside @Required to signal it's mandatory as well as required. If the setter method is non configured alongside a value, as well as then jump container volition throw a BeanCreationException during the initialization stage of the bean. The required properties banking concern jibe happens before the container starts applying the holding values on to the bean

Here is an instance of @Required annotation inward Spring framework:

public class Profile{  private String username;   @Required  public void setUsername(String username){   this.username = username;   }   }

}

Here username holding is required as well as if setUsername() is non called or username is non set, the edible bean creation procedure volition fail.


That's nearly approximately of the essential Spring framework annotations. As a Java jump developer, you lot should know nearly them as well as larn when to purpose them inward your code. Though nosotros convey covered approximately of the basic as well as most of import annotations, at that spot are many to a greater extent than exists inward Spring framework as well as if you lot desire fifty-fifty to a greater extent than as well as then I encourage you lot to await at Spring Framework Master Class which covers Spring framework inward fine details.


Further Learning
Master Microservices alongside Spring Boot as well as Spring Cloud
Master Hibernate as well as JPA alongside Spring Boot inward 100 Steps
5 Free Spring Framework as well as Spring Boot Courses
15 Spring Boot Interview Questions alongside Answers
20 Spring MVC Interview Questions for Java Programmers
20 REST alongside Spring Interview Questions for Web developers
3 ways to larn Core Spring or Spring MVC better
6 Courses to larn Spring Framework Better

Thanks for reading this article thence far. If you lot similar divulge this listing of Spring framework annotations useful as well as then delight portion alongside your friends as well as colleagues. If you lot convey whatever questions or feedback as well as then delight driblet a note.

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