Spring控制Bean加载顺序的操作方法

@Component
public class FirstInitialization {

    @PostConstruct
    public void init(){
        System.out.println("我是第一个加载！");
    }

}

@Component
@DependsOn("firstInitialization")
public class SecondInitialization {

    @PostConstruct
    public void init(){
        System.out.println("我是第二个加载！");
    }

}

@Component
@DependsOn("secondInitialization")
public class ThirdInitialization {

    @PostConstruct
    public void init(){
        System.out.println("我是第三个加载！");
    }

}

@Component
@DependsOn("thirdInitialization")
public class ForthInitialization {

    @PostConstruct
    public void init(){
        System.out.println("我是第四个加载！");
    }

}

public class MyApplicationContextInitializer implements ApplicationContextInitializer {
    @Override
    public void initialize(ConfigurableApplicationContext applicationContext) {

        //将自定义的BeanFactoryPostProcessor实现类保存到ApplicationContext中
        applicationContext.addBeanFactoryPostProcessor(new MyBeanFactoryPostProcessor());
    }
}

/**
 * BeanFactoryPostProcessor的子类
 * 允许开发人员在Bean定义注册之前和之后对BeanDefinition进行自定义处理，例如添加，修改或删除Bean定义等。
 */
public class MyBeanFactoryPostProcessor implements BeanDefinitionRegistryPostProcessor {

    // 初始化需要排序的类，这里要保证插入顺序只能用LinkedHashMap
    private static final Map<String, Class> ORDER_BEAN_MAP = new LinkedHashMap<>() {
        {
            put("firstInitialization", FirstInitialization.class);
            put("secondInitialization", SecondInitialization.class);
            put("thirdInitialization", ThirdInitialization.class);
            put("forthInitialization", ForthInitialization.class);
        }
    };

    @Override
    public void postProcessBeanDefinitionRegistry(BeanDefinitionRegistry registry) throws BeansException {
        Optional.ofNullable(ORDER_BEAN_MAP.keySet()).orElse(new HashSet<>()).stream()
                .forEach(beanName -> {
                    // 初始化一个 Bean 定义
                    AbstractBeanDefinition beanDefinition = BeanDefinitionBuilder
                            .genericBeanDefinition().getBeanDefinition();

                    // 按顺序注册每个Bean
                    beanDefinition.setBeanClass(ORDER_BEAN_MAP.get(beanName));
                    registry.registerBeanDefinition(beanName, beanDefinition);
                });
    }
}