详解Spring系列之@ComponentScan批量注册bean

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        https://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/context
        https://www.springframework.org/schema/context/spring-context.xsd">

    <context:component-scan base-package="org.example"/>
</beans>

@Component
public class RepositoryA implements RepositoryBase {
}

@Component
public class Service1 {
    @Autowired
    private RepositoryBase repository;
}

@Configuration
@ComponentScan(basePackages = "com.crab.spring.ioc.demo08")
public class AppConfig {
}

 @org.junit.Test
    public void test_component_scan1() {
        AnnotationConfigApplicationContext context =
                new AnnotationConfigApplicationContext(AppConfig.class);
        Service1 service1 = context.getBean(Service1.class);
        System.out.println(service1);
        context.close();
    }

@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.TYPE)
@Documented
@Repeatable(ComponentScans.class)
public @interface ComponentScan {

	// 见 basePackages
	@AliasFor("basePackages")
	String[] value() default {};
	// 指定扫描组件的包路径，为空则默认是扫描当前类所在包及其子包
	@AliasFor("value")
	String[] basePackages() default {};
	// 指定要扫描带注释的组件的包 可替换basePackages
	Class<?>[] basePackageClasses() default {};
	// 用于命名 Spring 容器中检测到的组件的类
	Class<? extends BeanNameGenerator> nameGenerator() default BeanNameGenerator.class;
	// 指定解析bean作用域的类
	Class<? extends ScopeMetadataResolver> scopeResolver() default AnnotationScopeMetadataResolver.class;
	// 指示为检测到的组件生成代理的模式
	ScopedProxyMode scopedProxy() default ScopedProxyMode.DEFAULT;
	// 控制符合组件检测条件的类文件；建议使用下面的 includeFilters excludeFilters
	String resourcePattern() default ClassPathScanningCandidateComponentProvider.DEFAULT_RESOURCE_PATTERN;
	// 指示是否应启用使用 @Component @Repository @Service  @Controller 注释的类的自动检测。
	boolean useDefaultFilters() default true;
    // 指定哪些类型适合组件扫描。进一步将候选组件集从basePackages中的所有内容缩小到与给定过滤器或多个过滤			器匹配的基本包中的所有内容。
    // <p>请注意，除了默认过滤器（如果指定）之外，还将应用这些过滤器。将包含指定基本包下与给定过滤器匹配的任		何类型，即使它与默认过滤器不匹配
	Filter[] includeFilters() default {};
	//	定哪些类型不适合组件扫描
	Filter[] excludeFilters() default {};
	// 指定是否应为延迟初始化注册扫描的 bean
	boolean lazyInit() default false;
}

@Retention(RetentionPolicy.RUNTIME)
	@Target({})
	@interface Filter {

		// 过滤的类型  支持注解、类、正则、自定义等
		FilterType type() default FilterType.ANNOTATION;
		@AliasFor("classes")
		Class<?>[] value() default {};
		// 指定匹配的类型，多个时是OR关系
		@AliasFor("value")
		Class<?>[] classes() default {};
		// 用于过滤器的匹配模式，valua没有配置时的替代方法，根据type变化
		String[] pattern() default {};
	}

@Configuration
@ComponentScan(basePackages = "org.example",
        includeFilters = @Filter(type = FilterType.REGEX, pattern = ".*My.*Repository"),
        excludeFilters = @Filter(Repository.class))
public class AppConfig {
    // ...
}

/**
 * 自定义的bean名称生成策略
 * @author zfd
 * @version v1.0
 * @date 2022/1/19 9:07
 * @关于我 请关注公众号 螃蟹的Java笔记 获取更多技术系列
 */
public class MyNameGenerator implements BeanNameGenerator {
    public MyNameGenerator() {
    }

    @Override
    public String generateBeanName(BeanDefinition definition, BeanDefinitionRegistry registry) {
        // bean命名统一采用固定前缀+类名
        return "crab$$" + definition.getBeanClassName();
    }
}

@Configuration
@ComponentScan(basePackages = "com.crab.spring.ioc.demo08",
nameGenerator = MyNameGenerator.class)
public class AppConfig {
}

@org.junit.Test
public void test_name_generator() {
    AnnotationConfigApplicationContext context =
            new AnnotationConfigApplicationContext(AppConfig.class);
    Service1 service1 = context.getBean(Service1.class);
    Arrays.stream(context.getBeanNamesForType(service1.getClass())).forEach(System.out::println);
    System.out.println(service1);
    context.close();
}
// bean名称中存在我们自定义的命名了
crab$$com.crab.spring.ioc.demo08.Service1
com.crab.spring.ioc.demo08.Service1@769f71a9

@Scope("prototype") // 
@Repository
public class MovieFinderImpl implements MovieFinder {
    // ...
}

/**
 * 自定义作用域策略
 * @author zfd
 * @version v1.0
 * @date 2022/1/19 9:32
 * @关于我 请关注公众号 螃蟹的Java笔记 获取更多技术系列
 */
public class MyMetadataResolver implements ScopeMetadataResolver {
    @Override
    public ScopeMetadata resolveScopeMetadata(BeanDefinition definition) {
        ScopeMetadata metadata = new ScopeMetadata();
        // 指定原型作用域
        metadata.setScopeName(BeanDefinition.SCOPE_PROTOTYPE);
        // 代理模式为接口
        metadata.setScopedProxyMode(ScopedProxyMode.INTERFACES);
        return metadata;
    }
}

@Configuration
@ComponentScan(basePackages = "com.crab.spring.ioc.demo08",
// nameGenerator = FullyQualifiedAnnotationBeanNameGenerator.class)
nameGenerator = MyNameGenerator.class,
scopeResolver = MyMetadataResolver.class
)
public class AppConfig {
}

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Indexed
public @interface Component {

	// 指定组件名
	String value() default "";

}

@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component // 元注解@Component
public @interface Repository {
   @AliasFor(annotation = Component.class)
   String value() default "";

}

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Component // @Component 导致 @Service 以与 @Component 相同的方式处理
public @interface Service {

    // ...
}

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Controller
@ResponseBody
public @interface RestController {
	@AliasFor(annotation = Controller.class)
	String value() default "";
}

@Target({ElementType.TYPE, ElementType.METHOD})
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Scope(WebApplicationContext.SCOPE_SESSION)
public @interface SessionScope {

    // 重新声明了元注解的属性并赋予了默认值
    @AliasFor(annotation = Scope.class)
    ScopedProxyMode proxyMode() default ScopedProxyMode.TARGET_CLASS;

}