ParentBeanFactory解析

Z时代
2024-01-10
分类：综合

public interface HierarchicalBeanFactory extends BeanFactory {
	/**
	 * Return the parent bean factory, or {@code null} if there is none.
	 */
	@Nullable
	// 获取父工厂
	BeanFactory getParentBeanFactory();
	/**
	 * Return whether the local bean factory contains a bean of the given name,
	 * ignoring beans defined in ancestor contexts.
	 * <p>This is an alternative to {@code containsBean}, ignoring a bean
	 * of the given name from an ancestor bean factory.
	 * @param name the name of the bean to query
	 * @return whether a bean with the given name is defined in the local factory
	 * @see BeanFactory#containsBean
	 */
	boolean containsLocalBean(String name);
}

子接口ConfigurableBeanFactory包含了setParentBeanFactory方法

应用

// Check if bean definition exists in this factory.
//doGetBean 方法中获取bean首先从父工厂获取，没有了才自己创建bean
			BeanFactory parentBeanFactory = getParentBeanFactory();
			if (parentBeanFactory != null && !containsBeanDefinition(beanName)) {
				// Not found -> check parent.
				String nameToLookup = originalBeanName(name);
				if (parentBeanFactory instanceof AbstractBeanFactory) {
					return ((AbstractBeanFactory) parentBeanFactory).doGetBean(
							nameToLookup, requiredType, args, typeCheckOnly);
				}
				else if (args != null) {
					// Delegation to parent with explicit args.
					return (T) parentBeanFactory.getBean(nameToLookup, args);
				}
				else if (requiredType != null) {
					// No args -> delegate to standard getBean method.
					return parentBeanFactory.getBean(nameToLookup, requiredType);
				}
				else {
					return (T) parentBeanFactory.getBean(nameToLookup);
				}
			}