[Spring] @ServletComponentScan

@ServletComponentScan
@SpringBootApplication
public class ServletApplication {
	public static void main(String[] args) {
		SpringApplication.run(ServletApplication.class, args);
	}
}

스프링에서 서블릿을 사용하도록 환경을 만들 때 사용하는 @ServletComponentScan을 살펴보자. 스프링 하면 빼놓을 수 없는 것이 스프링 빈이다. 스프링 빈에 대해 공부를 해보았다면 @ComponentScan에 대해 알 것이다. 그렇다면 앞에 서블렛이 붙은 @ServletComponentScan은 무엇일까?

 

package org.springframework.boot.web.servlet;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

import jakarta.servlet.annotation.WebFilter;
import jakarta.servlet.annotation.WebListener;
import jakarta.servlet.annotation.WebServlet;

import org.springframework.context.annotation.Import;
import org.springframework.core.annotation.AliasFor;

/**
 * Enables scanning for Servlet components ({@link WebFilter filters}, {@link WebServlet
 * servlets}, and {@link WebListener listeners}). Scanning is only performed when using an
 * embedded web server.
 * <p>
 * Typically, one of {@code value}, {@code basePackages}, or {@code basePackageClasses}
 * should be specified to control the packages to be scanned for components. In their
 * absence, scanning will be performed from the package of the class with the annotation.
 *
 * @author Andy Wilkinson
 * @since 1.3.0
 * @see WebServlet
 * @see WebFilter
 * @see WebListener
 */
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import(ServletComponentScanRegistrar.class)
public @interface ServletComponentScan {

	/**
	 * Alias for the {@link #basePackages()} attribute. Allows for more concise annotation
	 * declarations e.g.: {@code @ServletComponentScan("org.my.pkg")} instead of
	 * {@code @ServletComponentScan(basePackages="org.my.pkg")}.
	 * @return the base packages to scan
	 */
	@AliasFor("basePackages")
	String[] value() default {};

	/**
	 * Base packages to scan for annotated servlet components. {@link #value()} is an
	 * alias for (and mutually exclusive with) this attribute.
	 * <p>
	 * Use {@link #basePackageClasses()} for a type-safe alternative to String-based
	 * package names.
	 * @return the base packages to scan
	 */
	@AliasFor("value")
	String[] basePackages() default {};

	/**
	 * Type-safe alternative to {@link #basePackages()} for specifying the packages to
	 * scan for annotated servlet components. The package of each class specified will be
	 * scanned.
	 * @return classes from the base packages to scan
	 */
	Class<?>[] basePackageClasses() default {};

}

스프링에서는 이렇게 설명하고 있다.

서블렛 컴포넌트들을 스캔하도록 해준다. 스캐닝은 내장된 웹 서버를 사용할 때만 수행된다.

즉, 스프링이 서블렛을 사용할 수 있도록 패키지 내의 서블렛들을 찾아서 다 등록해주는 애너테이션이다.