Top X Jump Framework Annotations For Coffee Developers

There is no dubiousness that Spring framework is ane of the most pop Java frameworks together with it has made the life of Java developer piece of cake yesteryear providing simply about awesome features inwards the terminal xv years. Spring uses dependency injection to configure together with bind your application together but it doesn't forcefulness you lot to implement ane of its interfaces. This allows you lot to code POJO (plain onetime Java objects), a shape alongside methods together with 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 together with many of them. You volition let out simply about of the most mutual annotations inwards this article, which is must for a Java developer to run 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 together with hence institute my agency towards Java based configuration.

What this proves is that Spring is constantly evolving together with you lot convey to dice on upward alongside its measuring to dice on yourself up-to-date together with knowing simply about essential Spring annotations volition surely assistance inwards your journeying of Spring.

If you lot convey been coding Java for a duad of months hence you lot may convey come upward across at to the lowest degree of the annotations. The type which starts alongside "@" like @Override, mayhap the most pop Java annotations ever. This dainty petty metadata tin practise wonders inwards damage of improving code character together with reducing the hazard of errors.

Ever since annotations were introduced inwards JDK 1.5 they convey completely changed the Java landscape alongside to a greater extent than together with to a greater extent than framework adopting them to furnish services together with features together with Spring is no different.

They brand heavy purpose of Annotations to furnish features you lot dear e.g. automatically detecting beans, creating their instances together with injecting them to the objects who ask them. Btw, if you lot are novel to Spring hence I propose you lot banking corporation jibe a comprehensive course of report like Spring Framework v Beginner to Guru, which volition non solely learn you lot these annotations but likewise other boundary fundamentals you lot ask to know to run effectively alongside Spring.

Spring Core Annotations for Java developers

Since annotations are providing the interface betwixt Java together with Spring, it's of import for a Java developer to hold upward familiar alongside the essential interface together with empathise what they practise together with how to purpose them. In this article, I'll percentage simply about of the essential Spring annotations which I intend a Java Spring developers should know.


@Configuration
This Spring annotation marks a shape equally a source of edible bean definitions together with 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 instantly you lot don't ask to practise that, you lot tin practise classes together with 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 inwards Java-based configuration.


@Bean
This Spring kernel annotation indicates that a method produces a edible bean to hold upward managed yesteryear the Spring container. This is usually used inwards the classes which are annotated alongside @Configuration annotation on the Java-based configuration inwards Spring.

Here is an representative of @Configuration together with @Bean annotation inwards 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 shape alongside @Configuration to betoken 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 likewise check Spring Framework v Beginner to Guru for to a greater extent than examples.

@Component
This is simply about other basic Spring annotation which tin plough your shape into a Spring edible bean at the auto-scan time. In general, non all the shape you lot practise volition hold upward Spring edible bean inwards your projection but if a shape depends upon simply about other shape together with you lot desire Spring to autowire that dependency hence you lot tin annotate the shape with @Component annotation.

One of the most pop examples of a @Component annotation is @Controller classes which human activity a Spring MVC controller together with handles HTTP requests. They are automatically detected yesteryear Spring using annotation-based configuration together with classpath scanning.

Again, this is a shape grade annotation together with hither is an example, inspired yesteryear my favorite Spring book, Spring inwards Action yesteryear Craig Walls:

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

Since this shape is annotated alongside @Component, they volition hold upward picked upward during component-scanning together with created equally a edible bean inwards 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 inwards Spring MVC, @Service is likewise a specialization of the @Component annotation which has no encapsulated state. You tin farther read my article, difference betwixt @Service together with @Controller annotations inwards Spring to acquire 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 shape member.

Here is simply about other representative from classic Spring inwards Action book:

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

When Spring volition come across this method, it volition endeavour to let out out a Spring edible bean alongside type Dessert together with tin telephone yell upward this method to inject the dependency.  See Spring inwards Action, inwards 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 inwards Spring application context hence Spring volition confuse together with non able to inject whatever dependency. Instead, it volition throw NoUniqueBeanDefinitionException.

You tin resolve that ambiguity yesteryear using @Qualifier annotation equally 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 upward injected into this method.



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

Here are a duad of examples of @value annotation inwards spring:

@Value("NA") private String name

This code injects default String value to belongings name, but instead of a simply patently string, you lot tin likewise inject values from the belongings file together with arrangement properties. See Spring Framework v Beginner to Guru for to a greater extent than examples.

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

For example, you lot tin annotate a method alongside @Required to betoken it's mandatory together with required. If the setter method is non configured alongside a value, hence boundary container volition throw a BeanCreationException during the initialization stage of the bean. The required properties banking corporation jibe happens before the container starts applying the belongings values on to the bean

Here is an representative of @Required annotation inwards Spring framework:

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

}

Here username belongings is required together with if setUsername() is non called or username is non set, the edible bean creation procedure volition fail.


That's nearly simply about of the essential Spring framework annotations. As a Java boundary developer, you lot should know nearly them together with acquire when to purpose them inwards your code. Though nosotros convey covered simply about of the basic together with most of import annotations, in that place are many to a greater extent than exists inwards Spring framework together with if you lot desire fifty-fifty to a greater extent than hence I encourage you lot to hold back at Spring Framework Master Class which covers Spring framework inwards fine details.


Further Learning
Master Microservices alongside Spring Boot together with Spring Cloud
Master Hibernate together with JPA alongside Spring Boot inwards 100 Steps
5 Free Spring Framework together with 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 acquire Core Spring or Spring MVC better
6 Courses to acquire Spring Framework Better

Thanks for reading this article hence far. If you lot similar let out this listing of Spring framework annotations useful hence delight percentage alongside your friends together with colleagues. If you lot convey whatever questions or feedback hence delight drib a note.