Spring Boot

μŠ€ν”„λ§ λΆ€νŠΈλŠ” ν•„μš”ν•œ ν™˜κ²½ 섀정을 μ΅œμ†Œν™”ν•˜κ³  κ°œλ°œμžκ°€ λΉ„μ¦ˆλ‹ˆμŠ€ λ‘œμ§μ— 집쀑할 수 μžˆλ„λ‘ λ„μ™€μ€˜ 생산생을 ν–₯μƒμ‹œμΌ°λ‹€.

νŠΉμ§•

  • μž„λ² λ””λ“œ ν†°μΊ£, μ œν‹°, μ–Έλ”ν† μš°λ₯Ό μ‚¬μš©ν•΄ 독립 싀행이 κ°€λŠ₯ν•œ μŠ€ν”„λ§ μ• ν”Œλ¦¬μΌ€μ΄μ…˜ 개발

  • 톡합 μŠ€νƒ€ν„°λ₯Ό μ œκ³΅ν•˜μ—¬ maven/gradle ꡬ성 κ°„μ†Œν™”

  • μŠ€νƒ€ν„°λ₯Ό ν†΅ν•œ μžλ™ν™”λœ μŠ€ν”„λ§ μ„€μ • 제곡

  • 번거둜운 XML μ„€μ • μš”κ΅¬ν•˜μ§€ μ•ŠμŒ

  • JAR을 μ‚¬μš©ν•΄ μžλ°” μ˜΅μ…˜λ§ŒμœΌλ‘œλ„ 배포 κ°€λŠ₯

  • μ• ν”Œλ¦¬μΌ€μ΄μ…˜μ˜ λͺ¨λ‹ˆν„°λ§κ³Ό 관리λ₯Ό μœ„ν•œ Spring Actuator 제곡

  • Spring Boot Reference Guideλ₯Ό μ°Έκ³ ν•΄ μŠ€νƒ€ν„° λ‚΄λΆ€μ˜ μ˜μ‘΄μ„±μ„ 확인할 수 μžˆλ‹€.

라이브러리

  • spring-boot-starter-web

    • spring-boot-starter-tomcat: ν†°μΊ£(μ›Ήμ„œλ²„)

    • spring-webmvc: μŠ€ν”„λ§ μ›Ή MVC

  • spring-boot-starter-thymeleaf: νƒ€μž„λ¦¬ν”„ ν…œν”Œλ¦Ώ μ—”μ§„(View)

  • spring-boot-starter: μŠ€ν”„λ§ λΆ€νŠΈ + μŠ€ν”„λ§ μ½”μ–΄ + λ‘œκΉ…

    • spring-boot

      • spring-core

    • spring-boot-starter-logging

      • logback, slf4j

  • spring-boot-starter-test: μŠ€ν”„λ§λΆ€νŠΈ ν…ŒμŠ€νŠΈ

μž₯단점

μž₯점

  • 각각의 μ˜μ‘΄μ„± 버전을 μ˜¬λ¦¬λŠ” 것이 쑰금 더 μˆ˜μ›”ν•˜λ‹€.

  • νŠΉμ • λΌμ΄λΈŒλŸ¬λ¦¬μ— 버그가 μžˆλ”λΌλ„ μŠ€ν”„λ§νŒ€μ˜ 버그 ν”½μŠ€ν•œ 버전을 λ°›κΈ° νŽΈλ¦¬ν•˜λ‹€.

  • κ°„λ‹¨ν•œ μ–΄λ…Έν…Œμ΄μ…˜ μ„€μ •μ΄λ‚˜ ν”„λ‘œνΌν‹° μ„€μ •μœΌλ‘œ 세뢀적인 μ„€μ • 없이 μ›ν•˜λŠ” κΈ°λŠ₯을 λΉ λ₯΄κ²Œ μ μš©ν•  수 μžˆλ‹€.

  • λ³„λ„μ˜ μ™Έμž₯ 톰캣을 μ„€μΉ˜ν•  ν•„μš”κ°€ μ—†λ‹€.

단점

  • 섀정을 κ°œμΈν™”ν•˜λ©΄ 버전을 올릴 λ•Œ κΈ°μ‘΄ μŠ€ν”„λ§ ν”„λ ˆμž„μ›Œν¬λ₯Ό μ‚¬μš©ν•˜λŠ” 것과 λ™μΌν•œ λΆˆνŽΈν•¨μ„ κ²ͺ을 수 μžˆλ‹€.

  • νŠΉμ • 섀정을 κ°œμΈν™” ν˜Ήμ€ μ„€μ • 자체λ₯Ό λ³€κ²½ν•˜κ³  μ‹Άλ‹€λ©΄, λ‚΄λΆ€μ˜ μ„€μ • μ½”λ“œλ₯Ό μ‚΄νŽ΄λ΄μ•Όν•˜λŠ” λΆˆνŽΈν•¨μ΄ μžˆλ‹€.

μžλ™ ν™˜κ²½ μ„€μ •

μŠ€ν”„λ§ λΆ€νŠΈ μžλ™ ν™˜κ²½μ„€μ •μ€ Web, H2, JDBCλ₯Ό λΉ„λ‘―ν•΄ μ•½ 100μ—¬ 개의 μžλ™ 섀정을 μ œκ³΅ν•œλ‹€. 그리고 μƒˆλ‘œ μΆ”κ°€λ˜λŠ” λΌμ΄λΈŒλŸ¬λ¦¬λŠ” μŠ€ν”„λ§ λΆ€νŠΈ μžλ™-μ„€μ • μ˜μ‘΄μ„±μ— 따라 섀정이 μžλ™ μ μš©λœλ‹€. μžλ™ 섀정은 @EnableAutoConfiguration (@Configurationκ³Ό λ°˜λ“œμ‹œ 같이 μ‚¬μš©) λ˜λŠ” @SpringBootApplication 쀑 ν•˜λ‚˜λ₯Ό μ‚¬μš©ν•˜λ©΄ λœλ‹€.

μŠ€ν”„λ§ ν”„λ ˆμž„μ›Œν¬μ—μ„œλŠ” μ˜μ‘΄μ„±μ„ 일일이 빈으둜 μ„€μ •ν–ˆμœΌλ‚˜, μŠ€ν”„λ§ λΆ€νŠΈλŠ” κ΄€λ ¨ μ˜μ‘΄μ„±μ„ μŠ€νƒ€ν„°λΌλŠ” 묢음으둜 μ œκ³΅ν•΄ μˆ˜λ™ 섀정을 μ§€μ–‘ν•œλ‹€.

@SpringBootApplication

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@SpringBootConfiguration
@EnableAutoConfiguration
@ComponentScan(
    excludeFilters = {@Filter(
    type = FilterType.CUSTOM,
    classes = {TypeExcludeFilter.class}
), @Filter(
    type = FilterType.CUSTOM,
    classes = {AutoConfigurationExcludeFilter.class}
)}
)
public @interface SpringBootApplication {
  ...
}
  • @SpringBootConfiguration : μŠ€ν”„λ§ λΆ€νŠΈμ˜ 섀정을 λ‚˜νƒ€λ‚΄λŠ” μ–΄λ…Έν…Œμ΄μ…˜

    • Spring의 @Configuration λŒ€μ²΄

    • μŠ€ν”„λ§λΆ€νŠΈ μ „μš©

  • @EnableAutoConfiguration : μžλ™ μ„€μ •μ˜ 핡심 μ–΄λ…Έν…Œμ΄μ…˜

    • 클래슀 κ²½λ‘œμ— μ§€μ •λœ λ‚΄μš©μ„ 기반으둜 μžλ™ μ„€μ •

    • νŠΉλ³„ν•œ 섀정값을 μΆ”κ°€ν•˜μ§€ μ•ŠμœΌλ©΄ defaultκ°’ μ„€μ •

  • @ComponentScan : νŠΉμ • νŒ¨ν‚€μ§€ 경둜λ₯Ό 기반으둜 @configurationμ—μ„œ μ‚¬μš©ν•  @Component μ„€μ • 클래슀λ₯Ό μ°ΎλŠ”λ‹€.

    • basePackages ν”„λ‘œνΌν‹° 값에 λ³„λ„λ‘œ 값을 μ„€μ •ν•˜μ§€ μ•ŠμœΌλ©΄, @ComponentScan이 μœ„μΉ˜ν•œ νŒ¨ν‚€μ§€κ°€ 루트 경둜둜 μ„€μ •

@EnableAutoConfiguration

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@AutoConfigurationPackage
@Import({AutoConfigurationImportSelector.class})
public @interface EnableAutoConfiguration {
    String ENABLED_OVERRIDE_PROPERTY = "spring.boot.enableautoconfiguration";

    Class<?>[] exclude() default {};

    String[] excludeName() default {};
}

μ—¬κΈ°μ„œ μžλ™ 섀정을 μ§€μ›ν•΄μ£ΌλŠ” μ–΄λ…Έν…Œμ΄μ…˜μ€ @Import({AutoConfigurationImportSelector.class})이닀.

public class AutoConfigurationImportSelector implements DeferredImportSelector, BeanClassLoaderAware, ResourceLoaderAware, BeanFactoryAware, EnvironmentAware, Ordered {
    private static final AutoConfigurationImportSelector.AutoConfigurationEntry EMPTY_ENTRY = new AutoConfigurationImportSelector.AutoConfigurationEntry();
    private static final String[] NO_IMPORTS = new String[0];
    private static final Log logger = LogFactory.getLog(AutoConfigurationImportSelector.class);
    private static final String PROPERTY_NAME_AUTOCONFIGURE_EXCLUDE = "spring.autoconfigure.exclude";
    private ConfigurableListableBeanFactory beanFactory;
    private Environment environment;
    private ClassLoader beanClassLoader;
    private ResourceLoader resourceLoader;
    private AutoConfigurationImportSelector.ConfigurationClassFilter configurationClassFilter;

    public AutoConfigurationImportSelector() {
    }

    public String[] selectImports(AnnotationMetadata annotationMetadata) {
        if (!this.isEnabled(annotationMetadata)) {
            return NO_IMPORTS;
        } else {
            AutoConfigurationImportSelector.AutoConfigurationEntry autoConfigurationEntry = this.getAutoConfigurationEntry(annotationMetadata);
            return StringUtils.toStringArray(autoConfigurationEntry.getConfigurations());
        }
    }
  ...
}

AutoConfigurationImportSelector λ‚΄λΆ€μ˜ selectImports()μ—λŠ” μžλ™ μ„€μ • 방식에 λŒ€ν•΄ 쑰금 더 μƒμ„Ένžˆ μ‚΄νŽ΄λ³Ό 수 μžˆλ‹€.

    protected AutoConfigurationImportSelector.AutoConfigurationEntry getAutoConfigurationEntry(AnnotationMetadata annotationMetadata) {
        if (!this.isEnabled(annotationMetadata)) {
            return EMPTY_ENTRY;
        } else {
            AnnotationAttributes attributes = this.getAttributes(annotationMetadata);
            List<String> configurations = this.getCandidateConfigurations(annotationMetadata, attributes);
            configurations = this.removeDuplicates(configurations);
            Set<String> exclusions = this.getExclusions(annotationMetadata, attributes);
            this.checkExcludedClasses(configurations, exclusions);
            configurations.removeAll(exclusions);
            configurations = this.getConfigurationClassFilter().filter(configurations);
            this.fireAutoConfigurationImportEvents(configurations, exclusions);
            return new AutoConfigurationImportSelector.AutoConfigurationEntry(configurations, exclusions);
        }
    }

getAutoConfigurationEntry() λ©”μ„œλ“œλ₯Ό 보면 removeDuplicates() μ’…λ³΅λœ μ„€μ •κ³Ό getExclusions()으둜 μ œμ™Έν•  섀정을 μ œμ™Έμ‹œμΌœμ£Όκ³  μžˆλ‹€. 그리고 λ‚˜μ„œ 이쀑에 ν”„λ‘œμ νŠΈμ—μ„œ μ‚¬μš©ν•˜λŠ” 빈만 μž„ν¬νŠΈν•  μžλ™ λŒ€μƒμœΌλ‘œ μ„ νƒν•˜κ³  μžˆλ‹€.

  • META-INF/spring.factories : μžλ™ μ„€μ • 타깃 클래슀 λͺ©λ‘. 이곳에 μ„ μ–Έλ˜μ–΄ μžˆλŠ” ν΄λž˜μŠ€λ“€μ΄ @EnableAutoConfiguration 의 νƒ€κ²Ÿ

  • META-INF/spring-configuration-metadata.json : μžλ™ 섀정에 μ‚¬μš©ν•  ν”„λ‘œνΌν‹° μ •μ˜ 파일.

    • 미리 κ΅¬ν˜„λ˜μ–΄ μžˆλŠ” μžλ™ 섀정에 ν”„λ‘œνΌν‹°λ§Œ μ£Όμž… μ‹œν‚€λ©΄ λœλ‹€.(별도 ν™˜κ²½μ„€μ • λΆˆν•„μš”)

  • org/springframework/boot/autoconfigure : 미리 κ΅¬ν˜„ν•΄λ†“μ€ μžλ™ μ„€μ • 리슀트

    • {νŠΉμ •μ„€μ •μ΄λ¦„}AutoConfiguration ν˜•μ‹μœΌλ‘œ 이름이 μ§€μ •λ˜μ–΄ 있음

μœ„ νŒŒμΌμ€ λͺ¨λ‘ spring-boot-autoconfiguration에 미리 μ •μ˜λ˜μ–΄ 있고, μ§€μ •λœ ν”„λ‘œνΌν‹° 값을 μ‚¬μš©ν•΄ μ„€μ • 클래슀 λ‚΄λΆ€ 값을 λ°”κΏ€ 수 μžˆλ‹€.

Spring Boot Reference Guide - Common Application propertiesμ—μ„œ ν”„λ‘œνΌν‹° 값을 μ‰½κ²Œ 확인할 수 μžˆλ‹€.

μžλ™ μ„€μ • μ–΄λ…Έν…Œμ΄μ…˜

μžλ™ μ„€μ • 쑰건 μ–΄λ…Έν…Œμ΄μ…˜

μ–΄λ…Έν…Œμ΄μ…˜

적용 쑰건

@ConditionalOnBean

ν•΄λ‹Ήν•˜λŠ” 빈 ν΄λž˜μŠ€λ‚˜ 이름이 미리 빈 νŒ©ν† λ¦¬μ— ν¬ν•¨λ˜μ–΄ μžˆλŠ” 경우

@ConditionalOnClass

ν•΄λ‹Ήν•˜λŠ” ν΄λž˜μŠ€κ°€ 클래슀 κ²½λ‘œμ— μžˆλŠ” 경우

@ConditionalOnCloudPlatform

ν•΄λ‹Ήν•˜λŠ” ν΄λΌμš°λ“œ ν”Œλž«νΌμ΄ ν™œμš© μƒνƒœμΈ 경우

@ConditionalOnExpression

SpEL에 μ˜μ‘΄ν•˜λŠ” 쑰건인 경우

@ConditionalOnJava

JVM 버전이 μΌμΉ˜ν•˜λŠ” 경우

@ConditionalOnJndi

JNDIκ°€ μ‚¬μš©κ°€λŠ₯ν•˜κ³  νŠΉμ • μœ„μΉ˜μ— μžˆλŠ” 경우

@ConditionalOnMissingBean

ν•΄λ‹Ήν•˜λŠ” 빈 ν΄λž˜μŠ€λ‚˜ 이름이 미리 빈 νŒ©ν† λ¦¬μ— ν¬ν•¨λ˜μ–΄ μžˆμ§€ μ•Šμ€ 경우

@ConditionalOnMissingClass

ν•΄λ‹Ήν•˜λŠ” ν΄λž˜μŠ€κ°€ 클래슀 κ²½λ‘œμ— 없을 경우

@ConditionalOnNotWebApplication

μ›Ή μ–΄ν”Œλ¦¬μΌ€μ΄μ…˜μ΄ μ•„λ‹Œκ²½μš°

@ConditionalOnProperty

νŠΉμ •ν•œ ν”Όλ‘œνΌν‹°κ°€ μ§€μ •ν•œ 값을 κ°–λŠ” 경우

@ConditionalOnResource

νŠΉμ • λ¦¬μ†ŒμŠ€κ°€ 클래슀 κ²½λ‘œμ— μžˆλŠ” 경우

@ConditionalOnSingleCandidate

μ§€μ •ν•œ 빈 ν΄λž˜μŠ€κ°€ 이미 빈 νŒ©ν† λ¦¬μ— ν¬ν•¨λ˜μ–΄ 있고 단일 ν›„λ³΄μžλ‘œ μ§€μ • κ°€λŠ₯ν•œ 경우

@ConditionalOnWebApplication

μ›Ή μ–΄ν”Œλ¦¬μΌ€μ΄μ…˜μΈ 경우

μžλ™ μ„€μ • μˆœμ„œ μ–΄λ…Έν…Œμ΄μ…˜

μ–΄λ…Έν…Œμ΄μ…˜

μ„€λͺ…

@AutoConfigureAfter

μ§€μ •ν•œ νŠΉμ • μžλ™ μ„€μ • ν΄λž˜μŠ€λ“€μ΄ 적용된 이후에 ν•΄λ‹Ή μžλ™ μ„€μ • 적용

@AutoConfigureBefore

μ§€μ •ν•œ νŠΉμ • μžλ™ μ„€μ • ν΄λž˜μŠ€λ“€μ΄ 적용된 이전에 ν•΄λ‹Ή μžλ™ μ„€μ • 적용

@AutoConfigureOrder

μžλ™ μ„€μ • μˆœμ„œ 지정을 μœ„ν•œ μŠ€ν”„λ§ ν”„λ ˆμž„μ›Œν¬μ˜ @Order μ–΄λ…Έν…Œμ΄μ…˜ λ³€ν˜•μœΌλ‘œ κΈ°μ‘΄ μ„€μ • ν΄λž˜μŠ€μ—λŠ” 영ν–₯을 μ£Όμ§€ μ•Šκ³  μžλ™ μ„€μ • ν΄λž˜μŠ€λ“€ κ°„μ˜ μˆœμ„œλ§Œ μ§€μ •ν•œλ‹€.

μ˜ˆμ‹œ

@Configuration
@ConditionalOnWebApplication(type = ConditionalOnWebApplication.Type.SERVLET) // μ›Ή μ–΄ν”Œλ¦¬μΌ€μ΄μ…˜μΌ λ–„
@ConditionalOnClass(WebServlet.class) // WebServlet.classκ°€ κ²½λ‘œμ— μžˆμ„λ•Œ
@ConditionalOnProperty(prefix = "spring.h2.console" , name = "enabled", havingValue = "true", matchIfMissing = false) // spring.h2.console.enabled 값이 trueμΌλ•Œ
@EnableConfigurationProperties(H2ConsoleProperties.class)
public class H2ConsoleAutoConfiguration {
  ...
}

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