关于Spring框架应用BeanPostProcessor和BeanFactoryPostProcessor接口导致的注入及事务失效问题

喜欢ヅ旅行 2022-12-08 15:33 128阅读 0赞

# 前言： #

Spring框架是一个以IOC和AOP为核心的业务框架，在使用它时，会因为技术和业务的不断迭代，业务框架本身越来越庞大，对应的技术融合也越来越多，原来可以成功执行的，后面加入一些组件就导致了无效问题发生。

例如：使用了BeanPostProcessor或者BeanFactoryPostProcessor的一些用法，导致了BEAN的提 前初始化，随后在一些场景中，导致BEAN的注入无效、Spring的事务不起作用。

思考：在解决这些问题时，其实当时造成这种问题时，只是为了解决功能，但没有在整体方案上思考一个良好的规范。从而经常碰到有新的问题或功能来临时，将一些挖的坑给释放出来，从来变得既要向前兼容，还要解决新的功能问题的两难局面。

下面，作者专门编写了一个最简单的例子展现给大家。

--------------------

# 简单示例-准备： #

这里使用简单的示例，提前让一些BEAN初始化，导致spring的bean ioc无效引发空指针异常

编写applicationContext.xml 内容非常简单，配置一个数据源，并声明一个dao，并给它注入datasource

@Override
           <context:component-scan base-package="com.riso.spring"/>
    
        <bean id="dataSource" class="org.apache.commons.dbcp.BasicDataSource">
            <property name="driverClassName" value="com.mysql.jdbc.Driver"></property>
            <property name="url" value="jdbc:mysql://127.0.0.1:3306/test"></property>
            <property name="username" value="test"></property>
            <property name="password" value="test"></property>
            <property name="initialSize" value="2"></property>
            <property name="maxActive" value="5"></property>
        </bean>
    
        <bean class="com.riso.spring.dao.Test1DaoImpl">
            <property name="dataSource" ref="dataSource"/>
        </bean>

编写对应的简单dao和简单service

public class BaseDaoImpl { 
    
        private DataSource dataSource;
    
        private JdbcTemplate jdbcTemplate;
    
        public void setDataSource(DataSource dataSource) { 
            this.dataSource = dataSource;
            this.jdbcTemplate = new JdbcTemplate(this.dataSource);
        }
    
        public JdbcTemplate getJdbcTemplate() { 
            if (jdbcTemplate == null) { 
                throw new IllegalArgumentException("'dataSource' or 'jdbcTemplate' is required");
            }
            return jdbcTemplate;
        }
    
    }
    
     public class Test1DaoImpl extends BaseDaoImpl { 
    
        private static String INSERT_SQL = "insert into tr_test1(`test_name`) values(?)";
        
        public void insert(String testName) { 
            int count = getJdbcTemplate().update(INSERT_SQL, testName);
            log.debug("insert count:{}", count);
    
        }
    
    }
    
    @Service
    public class TestServiceImpl { 
    
        @Autowired
        private Test1DaoImpl test1Dao;
    
    
        @Transactional
        public void insertSingleSourceTrsSuccess() { 
            test1Dao.insert("testSuccess");
        }
    }

编写对应的单元测试

@RunWith(SpringJUnit4ClassRunner.class)
    @ContextConfiguration(locations = { "/applicationContext.xml"}) //加载spring配置文件 启动入口
    public class TestServiceImplTest { 
    
        @Autowired
        TestServiceImpl testService;
    
        @Test
        public void insertSingleSourceTrsSuccess() { 
            testService.insertSingleSourceTrsSuccess();
        }
    
    }

然后我们跑一下单元测试，结果是成功的  
![在这里插入图片描述][20200920153450675.png_pic_center]

--------------------

# 简单示例-复盘（添加BeanPostProcessor或者BeanFactoryPostProcessor使用，使依赖注入无效）： #

1.  添加一个BeanPostProcessor的实现(仅仅实现接口，仅仅打印日志，实测，不打日志，也是一样）

@Slf4j
    @Component
    public class MyBeanPostProcessor implements BeanPostProcessor { 
        @Override
        public Object postProcessBeforeInitialization(Object bean, String beanName) throws BeansException { 
           log.info("postProcessBeforeInitialization beanName:{}", beanName);
            return null;
        }
    
        @Override
        public Object postProcessAfterInitialization(Object bean, String beanName) throws BeansException { 
           log.info("postProcessAfterInitialization beanName:{}", beanName);
            return null;
        }
    }

然后跑一下单元测试，失败了  
![在这里插入图片描述][20200920154322851.png_pic_center]  
失败的异常见：

java.lang.IllegalStateException: Failed to load ApplicationContext
    
    	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:124)
    	at org.springframework.test.context.support.DefaultTestContext.getApplicationContext(DefaultTestContext.java:83)
    	at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.injectDependencies(DependencyInjectionTestExecutionListener.java:117)
    	at org.springframework.test.context.support.DependencyInjectionTestExecutionListener.prepareTestInstance(DependencyInjectionTestExecutionListener.java:83)
    	at org.springframework.test.context.TestContextManager.prepareTestInstance(TestContextManager.java:230)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.createTest(SpringJUnit4ClassRunner.java:228)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner$1.runReflectiveCall(SpringJUnit4ClassRunner.java:287)
    	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.methodBlock(SpringJUnit4ClassRunner.java:289)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:247)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
    	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
    	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
    	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
    	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)
    Caused by: org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'testMultiServiceImpl': Unsatisfied dependency expressed through field 'test1Dao'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.riso.spring.dao.Test1DaoImpl#0' defined in class path resource [applicationContext.xml]: Error setting property values; nested exception is org.springframework.beans.PropertyBatchUpdateException; nested PropertyAccessExceptions (1) are:
    PropertyAccessException 1: org.springframework.beans.MethodInvocationException: Property 'dataSource' threw exception; nested exception is java.lang.IllegalArgumentException: Property 'dataSource' is required
    	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588)
    	at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88)
    	at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366)
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264)
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553)
    	at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483)
    	at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306)
    	at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
    	at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302)
    	at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
    	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761)
    	at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867)
    	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543)
    	at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:128)
    	at org.springframework.test.context.support.AbstractGenericContextLoader.loadContext(AbstractGenericContextLoader.java:60)
    	at org.springframework.test.context.support.AbstractDelegatingSmartContextLoader.delegateLoading(AbstractDelegatingSmartContextLoader.java:108)
    	at org.springframework.test.context.support.AbstractDelegatingSmartContextLoader.loadContext(AbstractDelegatingSmartContextLoader.java:251)
    	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContextInternal(DefaultCacheAwareContextLoaderDelegate.java:98)
    	at org.springframework.test.context.cache.DefaultCacheAwareContextLoaderDelegate.loadContext(DefaultCacheAwareContextLoaderDelegate.java:116)
    	... 24 more

1.  删除掉BeanPostProcessor的实现， 添加一个BeanFactoryPostProcessor的实现（特别注意：beanFactory.getBeansWithAnnotation）

@Slf4j
    @Component
    public class MyBeanFactoryPostProcessor implements BeanFactoryPostProcessor { 
        @Override
        public void postProcessBeanFactory(ConfigurableListableBeanFactory beanFactory) throws BeansException { 
            int beanDefinitionCount = beanFactory.getBeanDefinitionCount();
            log.info("beanDefinitionCount:{}", beanDefinitionCount);
            String[] beanDefinitionNames = beanFactory.getBeanDefinitionNames();
            for (String beanDefinitionName : beanDefinitionNames) { 
                log.info("beanDefinitionName:{}", beanDefinitionName);
            }
            
            //Service 上面的代码是没有问题下面的代码是导致问题的关键代码
            Map<String, Object> annotationMap = beanFactory.getBeansWithAnnotation(Service.class);
    
    
        }
    }

然后跑一下单元测试，失败了  
![在这里插入图片描述][20200920154837752.png_pic_center]  
失败的异常见：（此次导致的问题 ，就是一个NullPointerException，还没有上面的错误的失败例子好分析。单看异常信息会莫名其妙

java.lang.NullPointerException
    	at com.riso.spring.service.TestServiceImpl.insertSingleSourceTrsSuccess(TestServiceImpl.java:19)
    	at com.riso.spring.service.TestServiceImplTest.insertSingleSourceTrsSuccess(TestServiceImplTest.java:21)
    	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    	at java.lang.reflect.Method.invoke(Method.java:498)
    	at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    	at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    	at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    	at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    	at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    	at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    	at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
    	at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
    	at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    	at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    	at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    	at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    	at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    	at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    	at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    	at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    	at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
    	at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    	at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    	at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
    	at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
    	at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)

--------------------

# 原因分析及解决方案： #

原因分析： 在使用spring的BeanPostProcessor和BeanFactoryPostProcessor的时候，在spring的初始化过程中，提前将还不打算实例化的bean，实例化了，这些实例化的BEAN，其实还有依赖一些配置或者BEAN，从来引发问题

解决方案有二个方案：  
1.在使用spring的BeanPostProcessor和BeanFactoryPostProcessor的时候，避免提前实例化bean的动作，这块引发的API可能有不少，作者本人也并没有枚举掉所有，需要实际项目人经过测试识别出来。

2.但作者本人认为根本的解决方案：  
建立一个BEAN的良好规范、比如说所有的BEAN应用，应该是懒加载的，从硬的代码生成，或软的开发标准上，都偏向于懒加载，避免在Spring本身的组件初始化及依赖引发的初始化，造成失效问题。

--------------------

# 查找问题中一些有参考意义的文章： #

[Spring 的类扫描器分析 - ClassPathBeanDefinitionScanner][Spring _ - ClassPathBeanDefinitionScanner]

[浅谈BeanPostProcessor加载次序及其对Bean造成的影响分析][BeanPostProcessor_Bean]

[Spring 钩子之BeanFactoryPostProcessor和BeanPostProcessor的源码学习][Spring _BeanFactoryPostProcessor_BeanPostProcessor]

# 最后附上我之前写的博文入口： #

\[1\] [https://blog.csdn.net/vipshop\_fin\_dev/article/details/89303458][https_blog.csdn.net_vipshop_fin_dev_article_details_89303458]  
\[2\] [https://blog.csdn.net/vipshop\_fin\_dev/article/details/85323076][https_blog.csdn.net_vipshop_fin_dev_article_details_85323076]  
\[3\] [https://blog.csdn.net/vipshop\_fin\_dev/article/details/85239099][https_blog.csdn.net_vipshop_fin_dev_article_details_85239099]  
\[4\] [https://blog.csdn.net/vipshop\_fin\_dev/article/details/79618067][https_blog.csdn.net_vipshop_fin_dev_article_details_79618067]  
\[5\] [https://blog.csdn.net/vipshop\_fin\_dev/article/details/79313432][https_blog.csdn.net_vipshop_fin_dev_article_details_79313432]  
\[6\] [https://blog.csdn.net/vipshop\_fin\_dev/article/details/106862227][https_blog.csdn.net_vipshop_fin_dev_article_details_106862227]

朱杰  
2020-09-20

[20200920153450675.png_pic_center]: /images/20221123/37e1ac16429e4a11b4ddebdbce04b6f8.png
[20200920154322851.png_pic_center]: /images/20221123/fed9d888a20b4148bc2fd45a1ee8d963.png
[20200920154837752.png_pic_center]: /images/20221123/c12d60c54d2f4abd81ebae8a94c92b20.png
[Spring _ - ClassPathBeanDefinitionScanner]: https://www.jianshu.com/p/d5ffdccc4f5d
[BeanPostProcessor_Bean]: http://www.manongjc.com/article/96047.html
[Spring _BeanFactoryPostProcessor_BeanPostProcessor]: https://www.jianshu.com/p/a90a3e617ba6
[https_blog.csdn.net_vipshop_fin_dev_article_details_89303458]: https://blog.csdn.net/vipshop_fin_dev/article/details/89303458
[https_blog.csdn.net_vipshop_fin_dev_article_details_85323076]: https://blog.csdn.net/vipshop_fin_dev/article/details/85323076
[https_blog.csdn.net_vipshop_fin_dev_article_details_85239099]: https://blog.csdn.net/vipshop_fin_dev/article/details/85239099
[https_blog.csdn.net_vipshop_fin_dev_article_details_79618067]: https://blog.csdn.net/vipshop_fin_dev/article/details/79618067
[https_blog.csdn.net_vipshop_fin_dev_article_details_79313432]: https://blog.csdn.net/vipshop_fin_dev/article/details/79313432
[https_blog.csdn.net_vipshop_fin_dev_article_details_106862227]: https://blog.csdn.net/vipshop_fin_dev/article/details/106862227