聊聊dubbo的DubboComponentScanRegistrar

public class DubboComponentScanRegistrar implements ImportBeanDefinitionRegistrar {
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    @Override
    public void registerBeanDefinitions(AnnotationMetadata importingClassMetadata, BeanDefinitionRegistry registry) {
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        Set<String> packagesToScan = getPackagesToScan(importingClassMetadata);
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        registerServiceAnnotationBeanPostProcessor(packagesToScan, registry);
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        registerReferenceAnnotationBeanPostProcessor(registry);
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    }
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    /**
     * Registers {@link ServiceAnnotationBeanPostProcessor}
     *
     * @param packagesToScan packages to scan without resolving placeholders
     * @param registry       {@link BeanDefinitionRegistry}
     * @since 2.5.8
     */
    private void registerServiceAnnotationBeanPostProcessor(Set<String> packagesToScan, BeanDefinitionRegistry registry) {
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        BeanDefinitionBuilder builder = rootBeanDefinition(ServiceAnnotationBeanPostProcessor.class);
        builder.addConstructorArgValue(packagesToScan);
        builder.setRole(BeanDefinition.ROLE_INFRASTRUCTURE);
        AbstractBeanDefinition beanDefinition = builder.getBeanDefinition();
        BeanDefinitionReaderUtils.registerWithGeneratedName(beanDefinition, registry);
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    }
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    /**
     * Registers {@link ReferenceAnnotationBeanPostProcessor} into {@link BeanFactory}
     *
     * @param registry {@link BeanDefinitionRegistry}
     */
    private void registerReferenceAnnotationBeanPostProcessor(BeanDefinitionRegistry registry) {
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        // Register @Reference Annotation Bean Processor
        BeanRegistrar.registerInfrastructureBean(registry,
                ReferenceAnnotationBeanPostProcessor.BEAN_NAME, ReferenceAnnotationBeanPostProcessor.class);
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    }
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    private Set<String> getPackagesToScan(AnnotationMetadata metadata) {
        AnnotationAttributes attributes = AnnotationAttributes.fromMap(
                metadata.getAnnotationAttributes(DubboComponentScan.class.getName()));
        String[] basePackages = attributes.getStringArray("basePackages");
        Class<?>[] basePackageClasses = attributes.getClassArray("basePackageClasses");
        String[] value = attributes.getStringArray("value");
        // Appends value array attributes
        Set<String> packagesToScan = new LinkedHashSet<String>(Arrays.asList(value));
        packagesToScan.addAll(Arrays.asList(basePackages));
        for (Class<?> basePackageClass : basePackageClasses) {
            packagesToScan.add(ClassUtils.getPackageName(basePackageClass));
        }
        if (packagesToScan.isEmpty()) {
            return Collections.singleton(ClassUtils.getPackageName(metadata.getClassName()));
        }
        return packagesToScan;
    }
​
}

public class DubboComponentScanRegistrarTest {
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    @BeforeEach
    public void setUp() {
        ConfigManager.getInstance().clear();
    }
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    @AfterEach
    public void tearDown() {
        ConfigManager.getInstance().clear();
    }
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    @Test
    public void test() {
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        AnnotationConfigApplicationContext providerContext = new AnnotationConfigApplicationContext();
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        providerContext.register(ProviderConfiguration.class);
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        providerContext.refresh();
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        DemoService demoService = providerContext.getBean(DemoService.class);
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        String value = demoService.sayName("Mercy");
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        Assertions.assertEquals("Hello,Mercy", value);
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        Class<?> beanClass = AopUtils.getTargetClass(demoService);
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        // DemoServiceImpl with @Transactional
        Assertions.assertEquals(DemoServiceImpl.class, beanClass);
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        // Test @Transactional is present or not
        Assertions.assertNotNull(findAnnotation(beanClass, Transactional.class));
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        AnnotationConfigApplicationContext consumerContext = new AnnotationConfigApplicationContext();
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        consumerContext.register(ConsumerConfiguration.class);
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        consumerContext.refresh();
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        ConsumerConfiguration consumerConfiguration = consumerContext.getBean(ConsumerConfiguration.class);
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        demoService = consumerConfiguration.getDemoService();
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        value = demoService.sayName("Mercy");
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        Assertions.assertEquals("Hello,Mercy", value);
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        ConsumerConfiguration.Child child = consumerContext.getBean(ConsumerConfiguration.Child.class);
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        // From Child
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        demoService = child.getDemoServiceFromChild();
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        Assertions.assertNotNull(demoService);
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        value = demoService.sayName("Mercy");
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        Assertions.assertEquals("Hello,Mercy", value);
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        // From Parent
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        demoService = child.getDemoServiceFromParent();
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        Assertions.assertNotNull(demoService);
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        value = demoService.sayName("Mercy");
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        Assertions.assertEquals("Hello,Mercy", value);
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        // From Ancestor
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        demoService = child.getDemoServiceFromAncestor();
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        Assertions.assertNotNull(demoService);
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        value = demoService.sayName("Mercy");
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        Assertions.assertEquals("Hello,Mercy", value);
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        providerContext.close();
        consumerContext.close();
​
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    }
​
​
}