1.概念

BeanDefinitionReader用于加载Bean,常规用到最多的就是bean的xml配置

2.示例

XmlBeanDefinitionReader需要传入一个BeanDefinitionRegistry实例,并调用loadBeanDefinitions方法加载一个xml文件的Resource资源
loadBeanDefinitions调用结束后xml中声明的bean就会注册到BeanDefinitionRegistry中

    @Test
    public void test() {
        SimpleBeanDefinitionRegistry registry = new SimpleBeanDefinitionRegistry();
        Resource resource = new InputStreamResource(getClass().getResourceAsStream("test.xml"));
        XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(registry);
        reader.loadBeanDefinitions(resource);
        testBeanDefinitions(registry);
    }

3.根据XmlBeanDefinitionReader来创建BeanFactory

protected BeanFactory createDefinition(String resourceLocation) {
        DefaultListableBeanFactory factory = new DefaultListableBeanFactory();
        XmlBeanDefinitionReader reader = new XmlBeanDefinitionReader(factory);
        ResourcePatternResolver resourcePatternResolver = new PathMatchingResourcePatternResolver();

        try {
            Resource[] configResources = resourcePatternResolver.getResources(resourceLocation);
            reader.loadBeanDefinitions(configResources);
        }
        catch (IOException ex) {
            throw new BeanDefinitionStoreException(
                    "Error accessing bean definition resource [" + this.resourceLocation + "]", ex);
        }
        catch (BeanDefinitionStoreException ex) {
            throw new FatalBeanException("Unable to load group definition: " +
                    "group resource name [" + this.resourceLocation + "]", ex);
        }

        return factory;
    }

参考文章:
Spring Bean 加载 - BeanDefinitionReader