spring-ioc(二)-注册配置类

不要问我阅读spring源码有什么用,问就是没有用,只是让我本身使用spring的过程当中自信点!

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注册配置类

直接看代码

public AnnotationConfigApplicationContext(Class<?>... annotatedClasses) {
        //这里在上篇已经说过了,主要是注册了几个spring内部的bean
	this();
	//本文的主要内容为下面这句的代码
	register(annotatedClasses);
	refresh();
}
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public void register(Class<?>... annotatedClasses) {
	Assert.notEmpty(annotatedClasses, "At least one annotated class must be specified");
	//这个读取器应该记得是 AnnotationConfigApplicationContext 的无参构造器中建立的吧,里面有一个注册器
	this.reader.register(annotatedClasses);
}
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public void register(Class<?>... annotatedClasses) {
	for (Class<?> annotatedClass : annotatedClasses) {
	       // 这里
		registerBean(annotatedClass);
	}
}
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<T> void doRegisterBean(Class<T> annotatedClass, @Nullable Supplier<T> instanceSupplier, @Nullable String name, @Nullable Class<? extends Annotation>[] qualifiers, BeanDefinitionCustomizer... definitionCustomizers) {
        //annotatedClass为你传递的参数,也就是本身的配置类
        //这个地方根据你的配置类的class类型去建立一个beanDefinition
        //之前额文章中我记得我说过 beanDefinition 是对bean 的描述,就行是Class 是对类的描述同样,只不过可能里面东西多了点
	AnnotatedGenericBeanDefinition abd = new AnnotatedGenericBeanDefinition(annotatedClass);
	//这个地方是判断当前类是否被Conditional注释
	if (this.conditionEvaluator.shouldSkip(abd.getMetadata())) {
		return;
	}
    
	abd.setInstanceSupplier(instanceSupplier);
	ScopeMetadata scopeMetadata = this.scopeMetadataResolver.resolveScopeMetadata(abd);
	//设置做用于 默认为singleton
	abd.setScope(scopeMetadata.getScopeName());
	//获取beanNam
	String beanName = (name != null ? name : this.beanNameGenerator.generateBeanName(abd, this.registry));
    //设置一些属性,例如Primary ,懒加载之类
	AnnotationConfigUtils.processCommonDefinitionAnnotations(abd);
	if (qualifiers != null) {
		for (Class<? extends Annotation> qualifier : qualifiers) {
			if (Primary.class == qualifier) {
				abd.setPrimary(true);
			}
			else if (Lazy.class == qualifier) {
				abd.setLazyInit(true);
			}
			else {
				abd.addQualifier(new AutowireCandidateQualifier(qualifier));
			}
		}
	}
	for (BeanDefinitionCustomizer customizer : definitionCustomizers) {
		customizer.customize(abd);
	}
        //建立beanDefinition 的持有者,其实呢也就是对beanDefinition进行封装
	BeanDefinitionHolder definitionHolder = new BeanDefinitionHolder(abd, beanName);
	definitionHolder = AnnotationConfigUtils.applyScopedProxyMode(scopeMetadata, definitionHolder, this.registry);
	//注册beanDefinition
	BeanDefinitionReaderUtils.registerBeanDefinition(definitionHolder, this.registry);
}
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解释beanDefinition

public AnnotatedGenericBeanDefinition(Class<?> beanClass) {
        //把当前class类型赋值给beanClass属性
	setBeanClass(beanClass);
	//建立一个注解元数据,这个还挺重要,其实也就是对当前类的注解进行封装保存下
	this.metadata = new StandardAnnotationMetadata(beanClass, true);
}
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public static void registerBeanDefinition( BeanDefinitionHolder definitionHolder, BeanDefinitionRegistry registry) throws BeanDefinitionStoreException {

	// Register bean definition under primary name.
	String beanName = definitionHolder.getBeanName();
	//去注册,传递的参数为 beanName beanDefinition
	registry.registerBeanDefinition(beanName, definitionHolder.getBeanDefinition());

	// Register aliases for bean name, if any.
	String[] aliases = definitionHolder.getAliases();
	//假如配置了别名,去设置别名
	if (aliases != null) {
		for (String alias : aliases) {
			registry.registerAlias(beanName, alias);
		}
	}
}
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注册的最后一段代码

@Override
public void registerBeanDefinition(String beanName, BeanDefinition beanDefinition) throws BeanDefinitionStoreException {

	Assert.hasText(beanName, "Bean name must not be empty");
	Assert.notNull(beanDefinition, "BeanDefinition must not be null");

	if (beanDefinition instanceof AbstractBeanDefinition) {
		try {
			((AbstractBeanDefinition) beanDefinition).validate();
		}
		catch (BeanDefinitionValidationException ex) {
			throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName,
					"Validation of bean definition failed", ex);
		}
	}
    //去beanDefinitionMap这个map中根据beanName查询下是否存在
	BeanDefinition existingDefinition = this.beanDefinitionMap.get(beanName);
	if (existingDefinition != null) {
	    //假如存在
		if (!isAllowBeanDefinitionOverriding()) {
			throw new BeanDefinitionOverrideException(beanName, beanDefinition, existingDefinition);
		}
		else if (existingDefinition.getRole() < beanDefinition.getRole()) {
			// e.g. was ROLE_APPLICATION, now overriding with ROLE_SUPPORT or ROLE_INFRASTRUCTURE
			if (logger.isInfoEnabled()) {
				logger.info("Overriding user-defined bean definition for bean '" + beanName +
						"' with a framework-generated bean definition: replacing [" +
						existingDefinition + "] with [" + beanDefinition + "]");
			}
		}
		else if (!beanDefinition.equals(existingDefinition)) {
			if (logger.isDebugEnabled()) {
				logger.debug("Overriding bean definition for bean '" + beanName +
						"' with a different definition: replacing [" + existingDefinition +
						"] with [" + beanDefinition + "]");
			}
		}
		else {
			if (logger.isTraceEnabled()) {
				logger.trace("Overriding bean definition for bean '" + beanName +
						"' with an equivalent definition: replacing [" + existingDefinition +
						"] with [" + beanDefinition + "]");
			}
		}
		//直接覆盖了
		this.beanDefinitionMap.put(beanName, beanDefinition);
	}
	else {
	        //不存在
		if (hasBeanCreationStarted()) {
			// Cannot modify startup-time collection elements anymore (for stable iteration)
			synchronized (this.beanDefinitionMap) {
				this.beanDefinitionMap.put(beanName, beanDefinition);
				List<String> updatedDefinitions = new ArrayList<>(this.beanDefinitionNames.size() + 1);
				updatedDefinitions.addAll(this.beanDefinitionNames);
				updatedDefinitions.add(beanName);
				this.beanDefinitionNames = updatedDefinitions;
				if (this.manualSingletonNames.contains(beanName)) {
					Set<String> updatedSingletons = new LinkedHashSet<>(this.manualSingletonNames);
					updatedSingletons.remove(beanName);
					this.manualSingletonNames = updatedSingletons;
				}
			}
		}
		else {
			// Still in startup registration phase
			//以beanName为key,beanDefinition为vlaue存入beanDefinitionMap
			//如今应该知道注册是意思了吧,就是把描述bean信息的beanDefinition 存放在一个map中
			this.beanDefinitionMap.put(beanName, beanDefinition);
			//把bean名字也存放下
			this.beanDefinitionNames.add(beanName);
			//这个暂时不知道干啥的
			this.manualSingletonNames.remove(beanName);
		}
		this.frozenBeanDefinitionNames = null;
	}

	if (existingDefinition != null || containsSingleton(beanName)) {
		resetBeanDefinition(beanName);
	}
}
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总结

1. 本文只是注册了一个配置类
2. 所谓的注册就是把描述bean信息的beanDefinition 存放在一个map中
3. 这个map叫作beanDefinitionMap它是bean工厂的一个属性
4. 注册器就是bean工厂自己