Spring – What’s the difference between and in servlet

springspring-3spring-mvc

I am migrating from Spring 2.5 to Spring 3.

They have introduced <mvc:annotation-driven /> which does some black magic. This is expected to be declared in servlet configuration file only.

In Spring 2.5 I have just used <context:annotation-config /> and <context:component-scan base='...'/> tags declared both in application-context.xml and dispatcher servlet configuration XML with appropriate base packages to scan.

So I wonder what is the difference between mvc:annotation-driven and context:annotation-config tags in servlet config and what can I eliminate in Spring 3 config files?

Best Answer

<context:annotation-config> declares support for general annotations such as @Required, @Autowired, @PostConstruct, and so on.

<mvc:annotation-driven /> declares explicit support for annotation-driven MVC controllers (i.e. @RequestMapping, @Controller, although support for those is the default behaviour), as well as adding support for declarative validation via @Valid and message body marshalling with @RequestBody/ResponseBody.

Related Solutions

Java – What’s the difference between @Component, @Repository & @Service annotations in Spring

From Spring Documentation:

The @Repository annotation is a marker for any class that fulfils the role or stereotype of a repository (also known as Data Access Object or DAO). Among the uses of this marker is the automatic translation of exceptions, as described in Exception Translation.

Spring provides further stereotype annotations: @Component, @Service, and @Controller. @Component is a generic stereotype for any Spring-managed component. @Repository, @Service, and @Controller are specializations of @Component for more specific use cases (in the persistence, service, and presentation layers, respectively). Therefore, you can annotate your component classes with @Component, but, by annotating them with @Repository, @Service, or @Controller instead, your classes are more properly suited for processing by tools or associating with aspects.

For example, these stereotype annotations make ideal targets for pointcuts. @Repository, @Service, and @Controller can also carry additional semantics in future releases of the Spring Framework. Thus, if you are choosing between using @Component or @Service for your service layer, @Service is clearly the better choice. Similarly, as stated earlier, @Repository is already supported as a marker for automatic exception translation in your persistence layer.

Annotation	Meaning
`@Component`	generic stereotype for any Spring-managed component
`@Repository`	stereotype for persistence layer
`@Service`	stereotype for service layer
`@Controller`	stereotype for presentation layer (spring-mvc)

Java – the difference between @Inject and @Autowired in Spring Framework? Which one to use under what condition

Assuming here you're referring to the javax.inject.Inject annotation. @Inject is part of the Java CDI (Contexts and Dependency Injection) standard introduced in Java EE 6 (JSR-299), read more. Spring has chosen to support using the @Inject annotation synonymously with their own @Autowired annotation.

So, to answer your question, @Autowired is Spring's own annotation. @Inject is part of a Java technology called CDI that defines a standard for dependency injection similar to Spring. In a Spring application, the two annotations works the same way as Spring has decided to support some JSR-299 annotations in addition to their own.

Best Answer

Related Solutions

Java – What’s the difference between @Component, @Repository & @Service annotations in Spring

Java – the difference between @Inject and @Autowired in Spring Framework? Which one to use under what condition

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