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业务类无法被AOP代理问题

在项目里面引入了 shiro 框架,然而在用户登录的时候始终会出现数据库访问异常,异常信息如下:

从异常日志来看是找错了数据库,因为项目中使用了多数据源技术,通过在service层加上 @DS(Database.DATABASE_CA_SYSTEM) 注解来标示该service需要使用哪个数据源。这个异常说明注解并没有实现它该有的作用。

多数据源使用的是 baomidou 开发的框架,相关依赖如下,它的核心是通过AOP技术来切换每个service需要使用的数据源,具体实现这里先不讨论。

<dependency>    
    <groupId>com.baomidou</groupId>    
    <artifactId>dynamic-datasource-spring-boot-starter</artifactId> 		    
</dependency>
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上面的异常说明 userService 这个 bean 并没有被代理,那么问题出来哪里呢?

问题定位

springboot 的启动日志中发现一个值得注意的点:

Warn: Could not find @TableId in Class: com.greenet.platform.common.entity.User. 2019-11-14 15:50:42.487 INFO 17752 --- [ main] trationDelegate BeanPostProcessorChecker : Bean 'userMapper' of type [com.sun.proxy. BeanPostProcessorChecker : Bean 'userService' of type [com.greenet.platform.common.service.impl.UserServiceImpl] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 2019-11-14 15:50:42.555 INFO 17752 --- [ main] trationDelegate$BeanPostProcessorChecker : Bean 'cacheManager' of type [org.apache.shiro.cache.ehcache.EhCacheManager] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 2019-11-14 15:50:42.556 INFO 17752 --- [ main] o.a.shiro.cache.ehcache.EhCacheManager : Using existing EHCache named [passwordRetryCache

重点在这句话:

trationDelegate$BeanPostProcessorChecker : Bean 'userService' of type [com.greenet.platform.common.service.impl.UserServiceImpl] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying)

这句话意思是 userService 由于不符合某种条件,导致不会被自动代理,那么这个条件是什么呢?

查看 BeanPostProcessorChecker 的源码,打印日志的地方如下:

@Overridepublic 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;
}
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日志打印出来的原因是 this.beanFactory.getBeanPostProcessorCount() < this.beanPostProcessorTargetCount 返回了 true ,也就是说此时注册到 beanFactory 的后置处理器数量是少于总的后置处理器数量的,也就是说这个时候有其他后置处理器还没准备好, userService 就已经被实例化了;

既然这个地方说了 userService 不会被代理,那么这个 bean 又是在什么时候被 spring 实例化的呢。想搞清楚这个问题很简单,可以在 AbstractBeanFactory.doGetBean 方法里面打一个条件断点,然后看调用栈。

业务类无法被AOP代理问题

得到如下调用栈:

"main@1" prio=5 tid=0x1 nid=NA runnable
  java.lang.Thread.State: RUNNABLE
	  at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:242)
	  at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
	  at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277)
	  at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1247)
	  at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1167)
	  at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:857)
	  at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:760)
	  at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:509)
	  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1305)
	  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1144)
	  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555)
	  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515)
	  at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
	  at org.springframework.beans.factory.support.AbstractBeanFactory$$Lambda$121.1862994526.getObject(Unknown Source:-1)
	  at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
	  - locked <0x12b7> (a java.util.concurrent.ConcurrentHashMap)
	  at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
	  at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199)
	  at org.springframework.beans.factory.config.DependencyDescriptor.resolveCandidate(DependencyDescriptor.java:277)
	  at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1247)
	  at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1167)
	  at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:857)
	  at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:760)
	  at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:509)
	  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1305)
	  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1144)
	  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.getSingletonFactoryBeanForTypeCheck(AbstractAutowireCapableBeanFactory.java:991)
	  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.getTypeForFactoryBean(AbstractAutowireCapableBeanFactory.java:865)
	  at org.springframework.beans.factory.support.AbstractBeanFactory.isTypeMatch(AbstractBeanFactory.java:574)
	  at org.springframework.beans.factory.support.DefaultListableBeanFactory.doGetBeanNamesForType(DefaultListableBeanFactory.java:514)
	  at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanNamesForType(DefaultListableBeanFactory.java:477)
	  at org.springframework.beans.factory.BeanFactoryUtils.beanNamesForTypeIncludingAncestors(BeanFactoryUtils.java:227)
	  at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1411)
	  at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1210)
	  at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:1167)
	  at org.springframework.beans.factory.support.ConstructorResolver.resolveAutowiredArgument(ConstructorResolver.java:857)
	  at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:760)
	  at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:509)
	  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1305)
	  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1144)
	  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:555)
	  at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515)
	  at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320)
	  at org.springframework.beans.factory.support.AbstractBeanFactory$$Lambda$121.1862994526.getObject(Unknown Source:-1)
	  at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222)
	  at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318)
	  at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:204)
	  at org.springframework.context.support.PostProcessorRegistrationDelegate.registerBeanPostProcessors(PostProcessorRegistrationDelegate.java:228)
	  at org.springframework.context.support.AbstractApplicationContext.registerBeanPostProcessors(AbstractApplicationContext.java:721)
	  at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:534)
	  - locked <0x12ea> (a java.lang.Object)
	  at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142)
	  at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775)
	  at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397)
	  at org.springframework.boot.SpringApplication.run(SpringApplication.java:316)
	  at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260)
	  at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248)
	  at com.greenet.platform.Application.main(Application.java:24)

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从调用栈可以看到两个重点信息:

AbstractBeanFactory.doGetBean
AbstractApplicationContext.registerBeanPostProcessors

这两点说明 userService 不是在正常的 AbstractApplicationContext.finishBeanFactoryInitialization 阶段通过实例化,而是在注册后置处理器的时候就实例化了。

为什么会提前实例化呢?

MethodValidationPostProcessor

从上面打的断点回头追溯到 registerBeanPostProcessors 的地方,可以看到此时注册的后置处理器 MethodValidationPostProcessor ,调试截图如下:

业务类无法被AOP代理问题

是对应的代码如下:

for (String ppName : orderedPostProcessorNames) {
			BeanPostProcessor pp = beanFactory.getBean(ppName, BeanPostProcessor.class);
			orderedPostProcessors.add(pp);
			if (pp instanceof MergedBeanDefinitionPostProcessor) {
				internalPostProcessors.add(pp);
			}
		}
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也就是说 userServiceMethodValidationPostProcessor 这个后置处理器注册前的实例化的过程中,因为某种原因被提前实例化了。

那么到底是为啥实例化 MethodValidationPostProcessor 的时候需要实例化 userService

通过一波调试发现,问题出来我的 shiro 配置里面

@Bean("securityManager")
    public SecurityManager securityManager(UserRealm userRealm,
                                           SessionManager sessionManager,
                                           EhCacheManager cacheManager) {
        DefaultWebSecurityManager securityManager = new DefaultWebSecurityManager();
        securityManager.setRealm(userRealm);
        securityManager.setSessionManager(sessionManager);
        securityManager.setRememberMeManager(null);
        securityManager.setCacheManager(cacheManager);
        return securityManager;
    }


    /**
     * shiro权限验证
     *
     * @param securityManager 安全管理器
     * @return 安全管理factorybean
     */
    @Bean("shiroFilter")
    public ShiroFilterFactoryBean shiroFilter(SecurityManager securityManager) {
        ShiroFilterFactoryBean shiroFilter = new ShiroFilterFactoryBean();
        shiroFilter.setSecurityManager(securityManager);
        shiroFilter.setLoginUrl("/login");

        Map<String, String> filterMap = new LinkedHashMap<>();

        filterMap.put("/static/**", "anon");
        filterMap.put("/", "anon");
        filterMap.put("/login/getVerifyCodeImage", "anon");

        filterMap.put("/**", "authc");
        shiroFilter.setFilterChainDefinitionMap(filterMap);

        return shiroFilter;
    }
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罪魁祸首是这个 ShiroFilterFactoryBean ,这个东西的定义如下:

public class ShiroFilterFactoryBean implements FactoryBean, BeanPostProcessor {
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它实现了 FactoryBean, BeanPostProcessor 这两个特殊的接口,所有的 FactoryBean 会在后置处理器 MethodValidationPostProcessor 实例化过程中被实例化,为啥呢,这跟这个后置处理器的定义的地方有关系,这个后置处理器在 ValidationAutoConfiguration 类中定义,具体方法代码如下:

@Bean
	@ConditionalOnMissingBean
	public static MethodValidationPostProcessor methodValidationPostProcessor(
			Environment environment, @Lazy Validator validator) {
		MethodValidationPostProcessor processor = new MethodValidationPostProcessor();
		boolean proxyTargetClass = environment
				.getProperty("spring.aop.proxy-target-class", Boolean.class, true);
		processor.setProxyTargetClass(proxyTargetClass);
		processor.setValidator(validator);
		return processor;
	}
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想要实例化这个类,需要指导这个方法的参数,问题就出在这个 Environment 里面,为了找到类型为 Environment 的参数,spring会遍历整个 beanDefinitionNames ,然后去找到符合 Environment 这个类型的 bean ,找的过程中发现有些 beanfactoryBean ,那不好意思,需要把这个 factoryBean 给实例化出来,再看上面 ShiroFilterFactoryBean 定义的方法可以看到,它依赖了 securityManager ,而 securityManager 又依赖了 userRealm ,而 userRealm 有依赖了 userService :

@Component
public class UserRealm extends AuthorizingRealm {

    private static final String ACCOUNT_TYPE_WEB = "2";
    private static final String ACCOUNT_TYPE_ALL = "255";

    @Autowired
    UserService userService;
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就这样一步步把 userService 给实例化了,这个时候还没到后置处理器处理bean的时候,那负责做AOP代理的后置处理器自然无法再去处理 userService 了。

原文  https://juejin.im/post/5dce403a51882510ab678a8a
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