Spring @Import注解的使用

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

	/**
	 * {@link Configuration}, {@link ImportSelector}, {@link ImportBeanDefinitionRegistrar}
	 * or regular component classes to import.
	 */
	Class<?>[] value();

}

<dependencies>
    <dependency>
        <groupId>org.projectlombok</groupId>
        <artifactId>lombok</artifactId>
        <version>1.18.18</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
        <version>4.3.24.RELEASE</version>
    </dependency>
</dependencies>

@Data
public class Tom {
    private String color;
    private Integer age;
}

@Configuration
public class AppConfig {
}

public class App {
    public static void main(String[] args) {
        // 创建容器
        AnnotationConfigApplicationContext context = new AnnotationConfigApplicationContext(AppConfig.class);
        // 获取bean
        Tom tom = context.getBean(Tom.class);
        System.out.println(tom);
    }
}

@Configuration
public class CustomConfiguration {
    @Bean
    public Tom tom() {
        Tom tom = new Tom();
        tom.setAge(11);
        tom.setColor("红色");
        return tom;
    }
}

@Import({ CustomConfiguration.class })
@Configuration
public class AppConfig {
}

public class CustomSelector implements ImportSelector {

    @Override
    public String[] selectImports(AnnotationMetadata importingClassMetadata) {
        return new String[] { "com.moli.pojo.Tom" };
    }
}

@Import({ CustomRegistrar.class })
@Configuration
public class AppConfig {
}

public class CustomRegistrar implements ImportBeanDefinitionRegistrar {
    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
        BeanDefinitionBuilder builder = BeanDefinitionBuilder.genericBeanDefinition(Tom.class);
        builder.setScope(BeanDefinition.SCOPE_SINGLETON);
        builder.addPropertyValue("color", "灰色");
        builder.addPropertyValue("age", "12");
        registry.registerBeanDefinition("tom", builder.getBeanDefinition());
    }
}

@Import({ CustomSelector.class })
@Configuration
public class AppConfig {
}

@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Import({ CustomRegistrar.class })
public @interface EnableTom {
}

@EnableTom
@Configuration
public class AppConfig {
}

@SuppressWarnings("deprecation")
@Target(ElementType.TYPE)
@Retention(RetentionPolicy.RUNTIME)
@Documented
@Inherited
@AutoConfigurationPackage
@Import(EnableAutoConfigurationImportSelector.class)
public @interface EnableAutoConfiguration {
    ...
}