Spring Boot

Dependency Injection

@Resource	Annotation used to inject an object that is already in the Appl­ication Context. It searches the instance by name. It also works on setter methods.
@Autowired	Annotation used to inject objects in many possible ways, such as: instance variable, constr­uctor and methods. It does not rely on name as @Reso­urce, so, for multiple concrete implem­ent­ations, the @Qual­ifier annotation must be used with it.
@Qualifier	Annotation used to dist­ing­uish between mult­iple concrete implem­ent­ations. Used alongside with @Auto­wired annotation that does not rely on name.
@Primary	Annotation used when no name is provided telling Spring to inject an object of the annotated class first. Used along with @Comp­onent.
@Component	Generic stereotype annotation used to tell Spring to create an instance of the object in the Appl­ication Context. It's possible to define any name for the instance, the default is the class name as camel case.
@Contr­oller	Stereotype annotation for presen­tation layer.
@Repos­itory	Stereotype annotation for persis­tence layer.
@Service	Stereotype annotation for service layer.

Modules Core spring-core spring-beans spring-context spring-expression AOP and Instrumentation spring-aop spring-aspects spring-instrument spring-instrument-tomcat Messaging spring­-me­ssaging Data Access­/In­teg­ration spring-jdbc spring-tx spring-orm spring-oxm spring-jms Web spring-web spring-webmvc spring-webmvc-portlet spring-websocket Test spring­-test Spring MVC @Controller Annotation to indicate that the class is a controller class. @RestController A conven­ience annotation that is itself annotated with @Cont­roller and @Resp­ons­eBody. Used in contro­llers that will behave as RESTful resour­ces. @RequestMapping Annotation to be used on methods in @Rest­Con­tro­ller classes. You can provide an URI to be served as RESTful service. @ModelAttribute Annotation used to bind values present in views.

Spring Properties Evaluation Sequence

Command-line arguments	java -Dproj­ect.na­me=Test -jar app.jar
System properties	Syste­m.g­etP­rop­ert­ies()
Enviro­nment Variable	export PROJEC­T_N­AME­=Test
External proper­tie­s/yml file	proje­ct.n­am­e=Test
Internal proper­tie­s/yml file	proje­ct.n­am­e=Test

Spring Boot Bootstrapped Annotations

@SpringBootApplication	Initial annotation that comprises the following annota­tions: @Spri­ngB­oot­Con­fig­ura­tion, @Enab­leA­uto­Con­fig­ura­tion and @Comp­one­ntS­can.
@Spri­­ngB­­oo­t­C­on­­fig­­ur­a­tion	Indicates that a class provides Spring Boot applic­ation @Conf­igu­rat­ion.
@Enab­­leA­­ut­o­C­on­­fig­­ur­a­tion	Enable auto-c­onf­igu­ration of the Spring Applic­ation Context, attempting to guess and configure beans that you are likely to need.
@Comp­­one­­nt­S­can	Configures component scanning directives for use with @Conf­igu­ration classes.