@ComponentScan 的作用就是根據(jù)定義的掃描路徑，把符合掃描規(guī)則的類裝配到spring容器中，注解定義如下。

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package org.springframework.context.annotation;

import java.lang.annotation.Documented;
import java.lang.annotation.ElementType;
import java.lang.annotation.Repeatable;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;
import org.springframework.beans.factory.support.BeanNameGenerator;
import org.springframework.core.annotation.AliasFor;

@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
@Documented
@Repeatable(ComponentScans.class)
public @interface ComponentScan {
    @AliasFor("basePackages")
    String[] value() default {};

    @AliasFor("value")
    String[] basePackages() default {};

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

    Class<? extends BeanNameGenerator> nameGenerator() default BeanNameGenerator.class;

    Class<? extends ScopeMetadataResolver> scopeResolver() default AnnotationScopeMetadataResolver.class;

    ScopedProxyMode scopedProxy() default ScopedProxyMode.DEFAULT;

    String resourcePattern() default "**/*.class";

    boolean useDefaultFilters() default true;

    ComponentScan.Filter[] includeFilters() default {};

    ComponentScan.Filter[] excludeFilters() default {};

    boolean lazyInit() default false;

    @Retention(RetentionPolicy.RUNTIME)
    @Target({})
    public @interface Filter {
        FilterType type() default FilterType.ANNOTATION;

        @AliasFor("classes")
        Class<?>[] value() default {};

        @AliasFor("value")
        Class<?>[] classes() default {};

        String[] pattern() default {};
    }
}

basePackages與value: 用于指定包的路徑，進(jìn)行掃描

basePackageClasses: 用于指定某個(gè)類的包的路徑進(jìn)行掃描

nameGenerator: bean的名稱的生成器

useDefaultFilters: 是否開(kāi)啟對(duì)@Component，@Repository，@Service，@Controller的類進(jìn)行檢測(cè)

includeFilters: 包含的過(guò)濾條件

        FilterType.ANNOTATION：按照注解過(guò)濾

        FilterType.ASSIGNABLE_TYPE：按照給定的類型

        FilterType.ASPECTJ：使用ASPECTJ表達(dá)式

        FilterType.REGEX：正則

        FilterType.CUSTOM：自定義規(guī)則

excludeFilters: 排除的過(guò)濾條件，用法和includeFilters一樣