Note: Spring Boot - Version 2.4

General

  • From Spring 4.3 onward, a class with a single constructor does not require the annotation for autowired parameters.

Web

  • Class
    • @RestController
    • @RequestMapping("/PATH")
  • Method
    • @GetMapping("/PATH"), @PostMapping("/PATH")
    • Path Var 
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      @GetMapping("/PATH/{VAR1}/{VAR2}")
public ResponseEntity<?> get(@PathVariable("VAR1") String v1, @PathVariable("VAR2") String v2) {
}

Concurrency

Scheduling

  • @EnableScheduling
  • private final TaskScheduler taskScheduler - Inject Scheduler
  • @Scheduled(initialDelayString="", fixedDelayString="") - On Method(s)

Custom Properties

  • Add dependency Maven Central
  • The class 
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    @Component
@ConfigurationProperties(prefix = "my.prefix")
public class TheProperties {
  // ...
}
  • In case of a simple POJO to be used as configuration (e.g. third-party code), define a method like the following one 
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    @SpringBootApplication
public class MyApp {
  // ...
  
  @Bean
  @ConfigurationProperties(prefix = "my.prefix")
  public TheProperties createProperties() {
    return new TheProperties();
  }
}

Note: use @Component over each class or apply @ConfigurationPropertiesScan to scan base package.

Configuration

  • Externalized Configuration
  • Enable autoconfiguration report, conditions evaluation report consists of multiple sections such as positive matches, negative matches, exclusions, unconditional classes, etc via
    • java -jar APP.jar --debug
    • java -Ddebug=true -jar APP.jar
    • debug=true - in application.properties
    • export DEBUG=true - as OS env
  • pom.xml
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<properties>
  <java.version>11</java.version>
</properties>
  • application.yml - Simple Sample
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server:
  shutdown: graceful
  
spring:
  profiles:
    active: prod
  lifecycle:
    timeout-per-shutdown-phase: 20s
  
---
  
spring:
  config:
    activate:
      on-profile: dev
  
logging:
  level:
    org.x.y.z: debug

Actuator

  • Add dependency Maven Central
  • Define policy on /actuator/** if security is enabled
  • management.endpoints.web.exposure.include=* - show all endpoints
  • Instead of *, a comma-separated list can be used such as
    • env - environment variables
    • configprops - config properties
    • metrics - some components specific metrics such as jvm, hikaricp, tomcat, …
    • mappings - list all request endpoints mappings to associated controller classes
    • heapdump
    • threaddump
  • management.endpoint.health.show-details=never|when_authorized|always - show detailed health info such as db, diskSpace, …

Security

  • Disable default security password in case of applying other options such as JWT [REF] 
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    @SpringBootApplication(exclude = {UserDetailsServiceAutoConfiguration.class})
public class MyApp {
  // ...
}