关于spring:Configuration中的来声明BeanPostProcessor和BeanFactoryPostProcessor

最近在遇到比拟一个问题，通常咱们在spring中应用@Configuration来注解一个类时，能够同时用Autowire 和@Value 给该配置类主动注入属性值，如下:

@Configurationpublic class ConfigA {   @Autowired   private Environment environment;   @Value("${name}")   private string name;   @Bean   public A a() {       A a = new A();       a.name = name;       return a;   }}

咱们失常状况下都是能主动注入environment和name的，然而当在configration 中如果申明了一个BeanPostProcessor时，如下：

   @Bean    public MyBeanPostProcessor myBeanPostProcessor(A a) {        log.info("env=:{}", environment);        MyBeanPostProcessor myBeanPostProcessor = new MyBeanPostProcessor();        myBeanPostProcessor.setA(a);        return myBeanPostProcessor;    }

你会发现打进去的log env 为null，同时A的name 也为null,这个配置类的 @Autowired和@Value都没有失效。
翻阅spring 的官网，其中有一段小tip,如下

    Make sure that the dependencies you inject that way are of the simplest kind only. @Configuration classes are processed quite early during the initialization of the context, and forcing a dependency to be injected this way may lead to unexpected early initialization. Whenever possible, resort to parameter-based injection, as in the preceding example.Also, be particularly careful with BeanPostProcessor and BeanFactoryPostProcessor definitions through @Bean. Those should usually be declared as static @Bean methods, not triggering the instantiation of their containing configuration class. Otherwise, @Autowired and @Value may not work on the configuration class itself, since it is possible to create it as a bean instance earlier than AutowiredAnnotationBeanPostProcessor.

意思就是BeanPostProcessor 和BeanFactoryPostProcessor 会在configuration 自身这个bean初始化之前，能够在spring onrefresh 办法中找到这段代码

踩坑记录一下。