spring技術內幕筆記:IoC容器的初始化過程(3)- BeanDefinition的註冊
阿新 • • 發佈:2019-01-31
Spring版本:4.3.8.RELEASE
DefaultListableBeanFactory中,通過一個HashMap來持有和載入BeanDefinition,解析得到的BeanDefinition向IoC容器的beanDefinitionMap註冊過程
是在載入BeanDefinition完成後進行的。在DefaultListableBeanFactory中實現了BeanDefinitionRegistry介面,這個介面的實現完成BeanDefinition向容器的註冊,這個過程就是把解析得到的BeanDefinition設定到hashMap中,進行BeanDefinition的註冊。
@SuppressWarnings("serial") public class DefaultListableBeanFactory extends AbstractAutowireCapableBeanFactory implements ConfigurableListableBeanFactory, BeanDefinitionRegistry, Serializable { /** bean definition物件的Map集合,key為bean的name*/ private final Map<String, BeanDefinition> beanDefinitionMap = new ConcurrentHashMap<String, BeanDefinition>(256); /** * 註冊BeanDefinition的過程 */ @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); } } BeanDefinition oldBeanDefinition; //檢查是不是有相同名字的BeanDefinition已經在IoC容器中註冊了,如果有相同的BeanDefinition,但又不允許覆蓋,會丟擲異常 oldBeanDefinition = this.beanDefinitionMap.get(beanName); if (oldBeanDefinition != null) { if (!isAllowBeanDefinitionOverriding()) { throw new BeanDefinitionStoreException(beanDefinition.getResourceDescription(), beanName, "Cannot register bean definition [" + beanDefinition + "] for bean '" + beanName + "': There is already [" + oldBeanDefinition + "] bound."); } else if (oldBeanDefinition.getRole() < beanDefinition.getRole()) { // e.g. was ROLE_APPLICATION, now overriding with ROLE_SUPPORT or ROLE_INFRASTRUCTURE if (this.logger.isWarnEnabled()) { this.logger.warn("Overriding user-defined bean definition for bean '" + beanName + "' with a framework-generated bean definition: replacing [" + oldBeanDefinition + "] with [" + beanDefinition + "]"); } } else if (!beanDefinition.equals(oldBeanDefinition)) { if (this.logger.isInfoEnabled()) { this.logger.info("Overriding bean definition for bean '" + beanName + "' with a different definition: replacing [" + oldBeanDefinition + "] with [" + beanDefinition + "]"); } } else { if (this.logger.isDebugEnabled()) { this.logger.debug("Overriding bean definition for bean '" + beanName + "' with an equivalent definition: replacing [" + oldBeanDefinition + "] with [" + beanDefinition + "]"); } } this.beanDefinitionMap.put(beanName, beanDefinition); } else { if (hasBeanCreationStarted()) { // 使用synchronized保持資料的一致性 synchronized (this.beanDefinitionMap) { this.beanDefinitionMap.put(beanName, beanDefinition); List<String> updatedDefinitions = new ArrayList<String>(this.beanDefinitionNames.size() + 1); updatedDefinitions.addAll(this.beanDefinitionNames); updatedDefinitions.add(beanName); this.beanDefinitionNames = updatedDefinitions; if (this.manualSingletonNames.contains(beanName)) { Set<String> updatedSingletons = new LinkedHashSet<String>(this.manualSingletonNames); updatedSingletons.remove(beanName); this.manualSingletonNames = updatedSingletons; } } } else { // 註冊BeanDefinition,將解析後BeanDefinition放入map,key為bean name,value為BeanDefinition物件 this.beanDefinitionMap.put(beanName, beanDefinition); this.beanDefinitionNames.add(beanName); this.manualSingletonNames.remove(beanName); } this.frozenBeanDefinitionNames = null; } if (oldBeanDefinition != null || containsSingleton(beanName)) { resetBeanDefinition(beanName); } } }