spring基础

###@Componet####

  1. @RestController @Service 注解等都是基于@component
    ###@componentScan 源码中的useDefaultFilter####
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    @Configuration
    @ComponentScan(value = "com.melon.app",
            includeFilters ={@ComponentScan.Filter(type =
                    FilterType.CUSTOM,classes = {MyTypeFilter.class})},
            useDefaultFilters = false)

其中useDefaultFilters为何要设置false的原因就是如果不设置都会扫描@component注解的类
源码分析

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AnnotationConfigApplicationContext->AbstractApplicationContext.refresh() 

	try {
		// Allows post-processing of the bean factory in context subclasses.
		postProcessBeanFactory(beanFactory);

		// 调用后置拦截器
		invokeBeanFactoryPostProcessors(beanFactory);

		// Register bean processors that intercept bean creation.
		registerBeanPostProcessors(beanFactory);
````	
>AbstractApplicationContextprotected

void invokeBeanFactoryPostProcessors(ConfigurableListableBeanFactory beanFactory)

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//调用后置拦截器
>> PostProcessorRegistrationDelegate

->invokeBeanFactoryPostProcessors(beanFactory, getBeanFactoryPostProcessors());
->invokeBeanDefinitionRegistryPostProcessors(currentRegistryProcessors, registry);
->for (BeanDefinitionRegistryPostProcessor postProcessor : postProcessors) {
postProcessor.postProcessBeanDefinitionRegistry(registry);
}

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> ConfigureClassPostProcessor

->postProcessBeanDefinitionRegistry
->processConfigBeanDefinitions
-> parser.parse(candidates);

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> ConfigureClassParser

->parse(Set configCandidates)
->if (bd instanceof AnnotatedBeanDefinition) {
parse(((AnnotatedBeanDefinition) bd).getMetadata(), holder.getBeanName());
}
->parse(AnnotationMetadata metadata, String beanName)
->processConfigurationClass(ConfigurationClass configClass)
-> doProcessConfigurationClass(configClass, sourceClass);
->Set scannedBeanDefinitions =
this.componentScanParser.parse(componentScan, sourceClass.getMetadata().getClassName());

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> ComponentScanAnnotationParser

->parse(AnnotationAttributes componentScan, final String declaringClass)
->ClassPathBeanDefinitionScanner scanner = new ClassPathBeanDefinitionScanner(this.registry,
componentScan.getBoolean(“useDefaultFilters”), this.environment, this.resourceLoader);

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> ClassPathBeanDefinitionScanner

->ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters,
Environment environment, @Nullable ResourceLoader resourceLoader)

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public ClassPathBeanDefinitionScanner(BeanDefinitionRegistry registry, boolean useDefaultFilters,
			Environment environment, @Nullable ResourceLoader resourceLoader) {

		Assert.notNull(registry, "BeanDefinitionRegistry must not be null");
		this.registry = registry;

		if (useDefaultFilters) {
			registerDefaultFilters();
		}
		setEnvironment(environment);
		setResourceLoader(resourceLoader);
	}

ClassPathScanningCandidateComponentProvider
····
protected void registerDefaultFilters() {
//默认情况下会扫描所有注解是component的类
this.includeFilters.add(new AnnotationTypeFilter(Component.class));
ClassLoader cl = ClassPathScanningCandidateComponentProvider.class.getClassLoader();
try {
this.includeFilters.add(new AnnotationTypeFilter(
((Class<? extends Annotation>) ClassUtils.forName(“javax.annotation.ManagedBean”, cl)), false));
logger.trace(“JSR-250 ‘javax.annotation.ManagedBean’ found and supported for component scanning”);
}
catch (ClassNotFoundException ex) {
// JSR-250 1.1 API (as included in Java EE 6) not available - simply skip.
}
try {
this.includeFilters.add(new AnnotationTypeFilter(
((Class<? extends Annotation>) ClassUtils.forName(“javax.inject.Named”, cl)), false));
logger.trace(“JSR-330 ‘javax.inject.Named’ annotation found and supported for component scanning”);
}
catch (ClassNotFoundException ex) {
// JSR-330 API not available - simply skip.
}
}