org.springframework.beans.factory.ListableBeanFactory#containsBean ( )源码实例Demo

/**
 * Obtain a bean of type {@code T} from the given {@code BeanFactory} declaring a qualifier
 * (e.g. {@code <qualifier>} or {@code @Qualifier}) matching the given qualifier).
 * @param bf the factory to get the target bean from
 * @param beanType the type of bean to retrieve
 * @param qualifier the qualifier for selecting between multiple bean matches
 * @return the matching bean of type {@code T} (never {@code null})
 */
private static <T> T qualifiedBeanOfType(ListableBeanFactory bf, Class<T> beanType, String qualifier) {
	String[] candidateBeans = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(bf, beanType);
	String matchingBean = null;
	for (String beanName : candidateBeans) {
		if (isQualifierMatch(qualifier::equals, beanName, bf)) {
			if (matchingBean != null) {
				throw new NoUniqueBeanDefinitionException(beanType, matchingBean, beanName);
			}
			matchingBean = beanName;
		}
	}
	if (matchingBean != null) {
		return bf.getBean(matchingBean, beanType);
	}
	else if (bf.containsBean(qualifier)) {
		// Fallback: target bean at least found by bean name - probably a manually registered singleton.
		return bf.getBean(qualifier, beanType);
	}
	else {
		throw new NoSuchBeanDefinitionException(qualifier, "No matching " + beanType.getSimpleName() +
				" bean found for qualifier '" + qualifier + "' - neither qualifier match nor bean name match!");
	}
}
 

/**
 * Obtain a bean of type {@code T} from the given {@code BeanFactory} declaring a qualifier
 * (e.g. {@code <qualifier>} or {@code @Qualifier}) matching the given qualifier).
 * @param bf the factory to get the target bean from
 * @param beanType the type of bean to retrieve
 * @param qualifier the qualifier for selecting between multiple bean matches
 * @return the matching bean of type {@code T} (never {@code null})
 */
private static <T> T qualifiedBeanOfType(ListableBeanFactory bf, Class<T> beanType, String qualifier) {
	String[] candidateBeans = BeanFactoryUtils.beanNamesForTypeIncludingAncestors(bf, beanType);
	String matchingBean = null;
	for (String beanName : candidateBeans) {
		if (isQualifierMatch(qualifier::equals, beanName, bf)) {
			if (matchingBean != null) {
				throw new NoUniqueBeanDefinitionException(beanType, matchingBean, beanName);
			}
			matchingBean = beanName;
		}
	}
	if (matchingBean != null) {
		return bf.getBean(matchingBean, beanType);
	}
	else if (bf.containsBean(qualifier)) {
		// Fallback: target bean at least found by bean name - probably a manually registered singleton.
		return bf.getBean(qualifier, beanType);
	}
	else {
		throw new NoSuchBeanDefinitionException(qualifier, "No matching " + beanType.getSimpleName() +
				" bean found for qualifier '" + qualifier + "' - neither qualifier match nor bean name match!");
	}
}