记一次Spring配置事故

在引入Spring的Validated时，需要声明如下bean：

@Bean
public MethodValidationPostProcessor methodValidationPostProcessor() {
    return new MethodValidationPostProcessor();
}

出于偷懒，放在了如下的一个初始化中：

@Configuration
public class ConfigService implements WebMvcConfigurer {

.........

    @Bean
    public MethodValidationPostProcessor methodValidationPostProcessor() {
        return new MethodValidationPostProcessor();
    }

.........

}

配置好后，@Validated生效了，但是aop，事务等出现异常。启动日志如下：

2018-08-25 20:03:09 [INFO] [main] [o.s.c.s.PostProcessorRegistrationDelegate$BeanPostProcessorChecker][328] Bean 'org.springframework.boot.context.properties.ConversionServiceDeducer$Factory' of type [org.springframework.boot.context.properties.ConversionServiceDeducer$Factory] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2018-08-25 20:03:09 [INFO] [main] [o.s.c.s.PostProcessorRegistrationDelegate$BeanPostProcessorChecker][328] Bean 'mybatis-org.mybatis.spring.boot.autoconfigure.MybatisProperties' of type [org.mybatis.spring.boot.autoconfigure.MybatisProperties] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2018-08-25 20:03:09 [INFO] [main] [o.s.c.s.PostProcessorRegistrationDelegate$BeanPostProcessorChecker][328] Bean 'org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration' of type [org.mybatis.spring.boot.autoconfigure.MybatisAutoConfiguration$$EnhancerBySpringCGLIB$$f57f05de] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2018-08-25 20:03:09 [INFO] [main] [o.s.c.s.PostProcessorRegistrationDelegate$BeanPostProcessorChecker][328] Bean 'org.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration$Hikari' of type [org.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration$Hikari] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2018-08-25 20:03:09 [INFO] [main] [o.s.c.s.PostProcessorRegistrationDelegate$BeanPostProcessorChecker][328] Bean 'spring.datasource-org.springframework.boot.autoconfigure.jdbc.DataSourceProperties' of type [org.springframework.boot.autoconfigure.jdbc.DataSourceProperties] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2018-08-25 20:03:09 [INFO] [main] [o.s.c.s.PostProcessorRegistrationDelegate$BeanPostProcessorChecker][328] Bean 'dataSource' of type [com.zaxxer.hikari.HikariDataSource] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2018-08-25 20:03:10 [INFO] [main] [o.s.c.s.PostProcessorRegistrationDelegate$BeanPostProcessorChecker][328] Bean 'sqlSessionFactory' of type [org.apache.ibatis.session.defaults.DefaultSqlSessionFactory] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)
2018-08-25 20:03:10 [INFO] [main] [o.s.c.s.PostProcessorRegistrationDelegate$BeanPostProcessorChecker][328] Bean 'sqlSessionTemplate' of type [org.mybatis.spring.SqlSessionTemplate] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)

从日志提示的地方看到如下代码：

        @Override
        public Object postProcessAfterInitialization(Object bean, String beanName) {
            if (!(bean instanceof BeanPostProcessor) && !isInfrastructureBean(beanName) &&
                    this.beanFactory.getBeanPostProcessorCount() < this.beanPostProcessorTargetCount) {
                if (logger.isInfoEnabled()) {
                    logger.info("Bean '" + beanName + "' of type [" + bean.getClass().getName() +
                            "] is not eligible for getting processed by all BeanPostProcessors " +
                            "(for example: not eligible for auto-proxying)");
                }
            }
            return bean;
        }

因为问题的引入是已知的，所以，在这里打了断点测试了下进入的条件。发现在加上MethodValidationPostProcessor的bean时，this.beanFactory.getBeanPostProcessorCount()获取到的值为10，不加这个bean时，获取到的值为21.那有问题，肯定是构造完成后，处理流程差异导致的问题。从构造函数开始寻找BeanPostProcessorChecker的初始化地点。

从这里找到PostProcessorRegistrationDelegate的registerBeanPostProcessors方法，

        int beanProcessorTargetCount = beanFactory.getBeanPostProcessorCount() + 1 + postProcessorNames.length;
        beanFactory.addBeanPostProcessor(new BeanPostProcessorChecker(beanFactory, beanProcessorTargetCount));

        // Separate between BeanPostProcessors that implement PriorityOrdered,
        // Ordered, and the rest.

从注释中可以看出，在初始化BeanPostProcessorChecker后，又继续初始化高优先级的，有顺序要求的，然后是剩下的BeanPostProcessor。

往下看：

        // First, register the BeanPostProcessors that implement PriorityOrdered.
        sortPostProcessors(priorityOrderedPostProcessors, beanFactory);
        registerBeanPostProcessors(beanFactory, priorityOrderedPostProcessors);

        // Next, register the BeanPostProcessors that implement Ordered.
        List<BeanPostProcessor> orderedPostProcessors = new ArrayList<>();
        for (String ppName : orderedPostProcessorNames) {
            BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
            orderedPostProcessors.add(pp);
            if (pp instanceof MergedBeanDefinitionPostProcessor) {
                internalPostProcessors.add(pp);
            }
        }
        sortPostProcessors(orderedPostProcessors, beanFactory);
        registerBeanPostProcessors(beanFactory, orderedPostProcessors);

        // Now, register all regular BeanPostProcessors.

在初始化高优先的BeanPostProcessor后，开始load带有顺序条件的BeanPostProcessor，准备初始化。

回到最开始，我们的MethodValidationPostProcessor的父类实现了Ordered接口。故也在这个for循环的加载过程中load进来，此时，在加载的时候出现问题。

在如下代码块中

@Configuration
public class ConfigService implements WebMvcConfigurer {
    @Resource
    private LogService logService;

    @Bean
    public MethodValidationPostProcessor methodValidationPostProcessor() {
        return new MethodValidationPostProcessor();
    }
}

我们注入了业务定义的bean，而这些bean是由最低优先级的BeanPostProcessor来加载并完成初始化的。但此时，为了加载其中的MethodValidationPostProcessor，导致不得不优先装载低优先级bean，此时，aop处理器，数据库处理器等都未完成装载，故由这部分业务bean牵扯到的相关逻辑的aop初始化，注解事务初始化，都事实上失败了。但spring就提示了一个INFO级别的提示，然后剩下的bean由最低优先级的BeanPostProcessor正常处理。

问题找到后，解决的方式很简单，由框架层初始化的bean，不要牵扯到业务层。不然即便初始化成功，也会导致一些模块因为顺序的缘故，未完成合适的处理流程，比如aop。

针对我这里的问题，如下解决：

@Configuration
public class MethodValidation {

    @Bean
    public MethodValidationPostProcessor methodValidationPostProcessor() {
        return new MethodValidationPostProcessor();
    }
}

重新创建一个类，单独初始化此类即可。