1. 实现步骤

1.1. 写一个自定义注解

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@Documented
@Inherited
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.TYPE})
public @interface WMapper {
}

1.2. 实现一个ImportBeanDefinitionRegistrar

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public static class HelloImportBeanDefinitionRegister implements ImportBeanDefinitionRegistrar {
        @Override
        public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
            //借助ClassPathBeanDefinitionScanner扫描类
            ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(registry, false);
            //加入自定义注解
            scanner.addIncludeFilter(new AnnotationTypeFilter(WMapper.class));
            //扫描指定包
            scanner.scan("io.github.weiwenduo");
        }
    }

1.3. 配置类

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@Configuration
@Import(HelloImportBeanDefinitionRegister.class)
public class HelloConfiguration {
}

1.4. 写一个类，加上我们的自定义注解

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@WMapper
public class HelloService {
}

1.5. 写一个测试类试一下

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@SpringBootTest(classes = SpringBasicApplication.class)
@ImportAutoConfiguration({HelloConfiguration.class})
public class Case1Test {

    @Autowired(required = false)
    private OtherService otherService;

    @Test
    public void test() {
        Optional.ofNullable(otherService).ifPresentOrElse(
                o -> System.out.println("otherService注入成功"),
                () -> System.out.println(OtherService.class.getSimpleName() + "为空，注入失败")
        );
    }

}

输入如下结果

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2021-03-03 16:06:51.421  INFO 97481 --- [           main] i.g.w.spring.test.case1.Case1Test        : No active profile set, falling back to default profiles: default
2021-03-03 16:06:51.655  INFO 97481 --- [           main] i.g.w.spring.test.case1.Case1Test        : Started Case1Test in 0.373 seconds (JVM running for 0.959)
otherService注入成功

说明类已经加载到Bean容器中了。