昨天下午的時候，給公司的項目打了個版，發現一直報502錯誤了，最后在服務器日志上看了一下異常信息，發現報了以下異常信息，導致項目啟動就報錯了（pc：該項目在我電腦本地啟動不報錯，之前也沒報錯）。
錯誤代碼如下：
org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'voucherDynamicDao': Bean with name 'voucherDynamicDao' has been injected into other beans [voucherServiceImpl] in its raw version as part of a circular reference, but has eventually been wrapped. This means that said other beans do not use the final version of the bean. This is often the result of over-eager type matching - consider using 'getBeanNamesOfType' with the 'allowEagerInit' flag turned off, for example. at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:622) ~[spring-beans-5.1.7.RELEASE.jar!/:5.1.7.RELEASE] at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:515) ~[spring-beans-5.1.7.RELEASE.jar!/:5.1.7.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:320) ~[spring-beans-5.1.7.RELEASE.jar!/:5.1.7.RELEASE] at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:222) ~[spring-beans-5.1.7.RELEASE.jar!/:5.1.7.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:318) ~[spring-beans-5.1.7.RELEASE.jar!/:5.1.7.RELEASE] at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:199) ~[spring-beans-5.1.7.RELEASE.jar!/:5.1.7.RELEASE] at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:843) ~[spring-beans-5.1.7.RELEASE.jar!/:5.1.7.RELEASE] at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:877) ~[spring-context-5.1.7.RELEASE.jar!/:5.1.7.RELEASE] at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:549) ~[spring-context-5.1.7.RELEASE.jar!/:5.1.7.RELEASE] at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:142) ~[spring-boot-2.1.5.RELEASE.jar!/:2.1.5.RELEASE] at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:775) ~[spring-boot-2.1.5.RELEASE.jar!/:2.1.5.RELEASE] at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:397) ~[spring-boot-2.1.5.RELEASE.jar!/:2.1.5.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:316) ~[spring-boot-2.1.5.RELEASE.jar!/:2.1.5.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1260) ~[spring-boot-2.1.5.RELEASE.jar!/:2.1.5.RELEASE] at org.springframework.boot.SpringApplication.run(SpringApplication.java:1248) ~[spring-boot-2.1.5.RELEASE.jar!/:2.1.5.RELEASE] at cn.exrick.xboot.XbootApplication.main(XbootApplication.java:58) ~[classes!/:0.0.1] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[na:na] at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62) ~[na:na] at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) ~[na:na] at java.base/java.lang.reflect.Method.invoke(Method.java:566) ~[na:na] at org.springframework.boot.loader.MainMethodRunner.run(MainMethodRunner.java:48) ~[xcr.dev.jar:0.0.1] at org.springframework.boot.loader.Launcher.launch(Launcher.java:87) ~[xcr.dev.jar:0.0.1] at org.springframework.boot.loader.Launcher.launch(Launcher.java:50) ~[xcr.dev.jar:0.0.1] at org.springframework.boot.loader.JarLauncher.main(JarLauncher.java:51) ~[xcr.dev.jar:0.0.1]
異常分析：
BeanCurrentlyInCreationException是一個依賴閉環的問題，一般A依賴B，B依賴C，C依賴A容易導致這個問題，這樣spring框架進行依賴注入創建bean的時候就容易發生異常。在本項目的代碼中，則是因為VoucherDynamicDao注入了依賴voucherServiceImpl，而VoucherServiceImpl又注入了voucherDynamicDao。（PC：這是同事寫的一段代碼，很久很久都沒動過，之前也沒發生過異常，昨天突然出現了，因此告誡大家：編程需謹慎，務必符合規范）
解決方案：
原代碼：
更正后的代碼:
我們的編程習慣都是Service提供接口，ServiceImpl為Service接口的實現類，而@Service組件注解以及@Transactional事務注解都是加在ServiceImpl類上的，通常我們在Controller層或者其他層調用ServiceImpl里面的方法時，寫的注入一般為service而不是serviceImpl，這樣可以有效的防止出現依賴閉環問題，編程也更規范。