spring循環依賴問題分析

新搞了一個單點登陸的項目，用的cas，要把源碼的cas-webapp改形成適合咱們業務場景的項目，因而新加了一些spring的配置文件。

可是在項目啓動時報錯了，錯誤日誌以下：

一月 08, 2016 11:01:34 下午 org.apache.catalina.core.StandardContext filterStart
嚴重: Exception starting filter springSecurityFilterChain
org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'functionServiceImpl': Bean with name 'functionServiceImpl' has been injected into other beans [platformServiceImpl] 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:548)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:296)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:293)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:628)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:389)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:294)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:112)
    at org.jasig.cas.web.init.SafeContextLoaderListener.contextInitialized(SafeContextLoaderListener.java:75)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:5003)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5517)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1574)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1564)
    at java.util.concurrent.FutureTask.run(FutureTask.java:262)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
    at java.lang.Thread.run(Thread.java:745)

去stackoverflow上面搜，說是spring循環依賴致使的。可是問了組裏一個技術牛，說若是是出現spring循環依賴，在啓動項目的時候是不會報錯的，spring的循環依賴在運行的時候纔會報錯。

循環依賴也可能出如今maven裏，若是maven配置中出現了循環依賴，編譯的時候就會報錯。

那麼，到底是什麼緣由，我如今還不知道。

在個人web.xml文件中，引入了兩次spring的applicationContext.xml文件。

  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>
      /WEB-INF/spring-configuration/*.xml
      /WEB-INF/deployerConfigContext.xml
      classpath:spring/applicationContext.xml
    </param-value>
  </context-param>

當我去掉我本身的spring配置時，項目啓動就不報錯了。

  <context-param>
    <param-name>contextConfigLocation</param-name>
    <param-value>
      /WEB-INF/spring-configuration/*.xml
      /WEB-INF/deployerConfigContext.xml      
    </param-value>
  </context-param>

那是否是由於加載了兩個applicationContext.xml，就至關於初始化了兩個spring容器，有的單例類只容許存在一個實例，可是卻出現了兩個容器的bean，因此報錯了呢？

具體問題待排查。

問題緣由查到了：

因爲剛開始配置spring的時候加載了2遍applicationContext.xml,其中有一個動態代理切面的配置在兩個配置文件中都存在重複了。詳情見：

http://www.cnphp6.com/archives/22031

其實，仍是由於bean加載重複了。