annotations cheat sheet

Spring Boot and Web annotations

Use annotations to configure your web application.

@SpringBootApplication - uses @Configuration,

@EnableAutoConfiguration and @ComponentScan.

@EnableAutoConfiguration - make Spring guess the

configuration based on the classpath.

@Controller - marks the class as web controller, capable

of handling the requests. @RestController - a convenience

annotation of a @Controller and @ResponseBody.

@ResponseBody - makes Spring bind method’s return

value to the web response body.

@RequestMapping - specify on the method in the

controller, to map a HTTP request to the URL to this method.

@RequestParam - bind HTTP parameters into

method arguments.

@PathVariable - binds placeholder from the URI

to the method parameter.

Spring Framework annotations

Spring Cloud annotations

Make you application work well in the cloud.

@EnableConfigServer - turns your application into

a server other apps can get their configuration from.

Use spring.application.cloud.config.uri in the client

@SpringBootApplication to point to the config server.

@EnableEurekaServer - makes your app an Eureka

discovery service, other apps can locate services through it.

@EnableDiscoveryClient - makes your app register in the

service discovery server and discover other services through it.

@EnableCircuitBreaker - configures Hystrix circuit

breaker protocols.

@HystrixCommand(fallbackMethod =

“fallbackMethodName”) - marks methods to fall back

to another method if they cannot succeed normally.

Spring uses dependency injection to configure and bind

your application together.

@ComponentScan - make Spring scan the package

for the @Configuration classes.

@Configuration - mark a class as a source of

bean definitions.

@Bean - indicates that a method produces a bean to be

managed by the Spring container.

@Component - turns the class into a Spring bean at the

auto-scan time. @Service - specialization of the

@Component, has no encapsulated state.

@Autowired - Spring’s dependency injection wires

an appropriate bean into the marked class member.

@Lazy - makes @Bean or @Component be initialized

on demand rather than eagerly.

@Qualifier - filters what beans should be used to

@Autowire a field or parameter.

@Value - indicates a default value expression for

the field or parameter, typically something like

“#{systemProperties.myProp}”

@Required - fail the configuration,

if the dependency cannot be injected.

For more awesome cheat sheets

visit rebellabs.org!

Legend

• class

• field annotation

• constructor annotation

• method

• parameter

@SpringBootApplication

HTTP Responses

@RestController

@Autowired

Service service;

@RequestMapping

public Map serveRequest()

@Configuration

@Bean

public MyBean

provideBean()

@Service

@Component

provides

beans

like these

beans

are

injected

Cloud

Configuration

server

Service

discovery

asks

configuration

receives

properties

asks services

location

receives URL

registers itself

as a service

HTTP Requests

T

F

C

M

P

F

C

M

F

C

M

F

C

M

T M

F

C

M

T

T

M

T

T

T

M

T

T

T

T

M

T

P

T

T

T

T

M

P