業務類無法被AOP代理問題
阿新 • • 發佈：2019-12-31
背景
在專案裡面引入了shiro框架，然而在使用者登入的時候始終會出現資料庫訪問異常，異常資訊如下：
org.springframework.jdbc.BadSqlGrammarException:
### Error querying database. Cause: java.sql.SQLSyntaxErrorException: Table 'ems.sys_user_manager' doesn't exist
### The error may exist in com/greenet/platform/common/mapper/UserMapper.java (best guess) 從異常日誌來看是找錯了資料庫，因為專案中使用了多資料來源技術，通過在service層加上@DS(Database.DATABASE_CA_SYSTEM)註解來標示該service需要使用哪個資料來源。這個異常說明註解並沒有實現它該有的作用,導致資料來源沒有切換成功。
多資料來源使用的是baomidou開發的框架,相關依賴如下，它的核心是通過AOP技術來切換每個service需要使用的資料來源，具體實現這裡先不討論。
<dependency>
<groupId>com.baomidou</groupId>
<artifactId>dynamic-datasource-spring-boot-starter</artifactId>
</dependency>
複製程式碼上面的異常說明userService這個bean並沒有被代理，那麼問題出來哪裡呢？
問題定位
springboot的啟動日誌中發現一個值得注意的點：
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$BeanPostProcessorChecker : Bean 'cacheManager' of type [org.apache.shiro.cache.ehcache.EhCacheManager] is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) 2019-11-14 15:50:42.556 INFO 17752 --- [ main] o.a.shiro.cache.ehcache.EhCacheManager : Using existing EHCache named [passwordRetryCache
重點在這句話：
trationDelegate$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)
這句話意思是userService由於不符合某種條件，導致不會被自動代理，那麼這個條件是什麼呢？
檢視BeanPostProcessorChecker的原始碼，列印日誌的地方如下：
@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;
}
複製程式碼日誌打印出來的原因是this.beanFactory.getBeanPostProcessorCount() < this.beanPostProcessorTargetCount返回了true,也就是說此時註冊到beanFactory的後置處理器數量是少於總的後置處理器數量的，也就是說這個時候有其他後置處理器還沒準備好，userService就已經被例項化了;
既然這個地方說了userService不會被代理，那麼這個bean又是在什麼時候被spring例項化的呢。想搞清楚這個問題很簡單，可以在AbstractBeanFactory.doGetBean方法裡面打一個條件斷點，然後看呼叫棧。
得到如下呼叫棧：
"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)
複製程式碼從呼叫棧可以看到兩個重點資訊：
- 這個棧裡面出現了三次
AbstractBeanFactory.doGetBean，說明userService是在例項化其他bean的時候由於依賴注入而例項化的； - 棧的入口是
AbstractApplicationContext.registerBeanPostProcessors
這兩點說明userService不是在正常的AbstractApplicationContext.finishBeanFactoryInitialization階段通過例項化，而是在註冊後置處理器的時候就例項化了。
為什麼會提前例項化呢？
MethodValidationPostProcessor
從上面打的斷點回頭追溯到registerBeanPostProcessors的地方，可以看到此時註冊的後置處理器MethodValidationPostProcessor，除錯截圖如下：
是對應的程式碼如下：
for (String ppName : orderedPostProcessorNames) {
BeanPostProcessor pp = beanFactory.getBean(ppName,BeanPostProcessor.class);
orderedPostProcessors.add(pp);
if (pp instanceof MergedBeanDefinitionPostProcessor) {
internalPostProcessors.add(pp);
}
}
複製程式碼也就是說userService在MethodValidationPostProcessor這個後置處理器註冊前的例項化的過程中，因為某種原因被提前例項化了。
那麼到底是為啥例項化MethodValidationPostProcessor的時候需要例項化userService呢
通過一波除錯發現，問題出來我的shiro配置裡面
@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許可權驗證
*
* @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;
}
複製程式碼罪魁禍首是這個ShiroFilterFactoryBean，這個東西的定義如下：
public class ShiroFilterFactoryBean implements FactoryBean,BeanPostProcessor {
複製程式碼它實現了FactoryBean,BeanPostProcessor這兩個特殊的介面，所有的FactoryBean會在後置處理器MethodValidationPostProcessor例項化過程中被例項化，為啥呢，這跟這個後置處理器的定義的地方有關係，這個後置處理器在ValidationAutoConfiguration類中定義，具體方法程式碼如下：
@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;
}
複製程式碼想要例項化這個類，需要知道這個方法的引數，問題就出在這個Environment裡面，為了找到型別為Environment的引數，spring會遍歷整個beanDefinitionNames，然後去找到符合Environment這個型別的bean，找的過程中發現有些bean是factoryBean，那不好意思，需要把這個factoryBean給例項化出來，再看上面ShiroFilterFactoryBean定義的方法可以看到，它依賴了securityManager，而securityManager又依賴了userRealm，而userRealm又依賴了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;
複製程式碼就這樣一步步把userService給例項化了，這個時候還沒到後置處理器處理bean的時候，那負責做AOP代理的後置處理器自然無法再去處理userService了。
解決方案
那麼如何去解決這個問題呢，思路是不要在factoryBean裡面去注入業務類。一種比較簡單的辦法是去注入ApplicationContext，然後通過getBean方法拿到業務的service
private UserService getUserService() {
return (UserService) applicationContext.getBean("userService");
}
複製程式碼