今天在做单元测试时候，出现了一个诡异的问题，异常如下：

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'incidentOrderService': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private com.suninfo.workflow.WorkFlowService com.suninfo.itil.impl.IncidentOrderServiceImpl.workFlowService; nested exception is org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'workflowService': Bean with name 'workflowService' has been injected into other beans [operationApproveOrderService] 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

从异常可以看出spring初始化bean的时候出现了循环引用的问题

场景还原：

项目大概结构：worflow(流程子工程)，config(配置子工程)，api（所有公共service子工程），其中config这个子工程放置了所有基础的、公有配置文件，比如spring-mybatis.xml，所有子工程都引用这个config子工程。

之前我所有activiti流程相关的配置都放在spring-mybatis.xml中的，我自己负责的工作流子工程（workflow）引用这个基础的配置文件，没有问题，但是别的子工程引用这个配置文件就会报错，因为我定义的流程相关的一个AOP的类是放在我流程（workflow）的子工程里的，别的子工程引用会报找不到这个类，如果这个子工程可以独立部署的话，这样肯定不行。

于是在workflow这个子工程里增加了spring-activiti.xml这个配置文件，同时这个配置文件也作为单元测试中spring的上下文，如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" 
	   xmlns:mvc="http://www.springframework.org/schema/mvc"
	   xmlns:aop="http://www.springframework.org/schema/aop" 
	   xmlns:tx="http://www.springframework.org/schema/tx"
	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:context="http://www.springframework.org/schema/context" 
       xsi:schemaLocation="
       	http://www.springframework.org/schema/beans
 		http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
        http://www.springframework.org/schema/aop 
        http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.0.xsd
        http://www.springframework.org/schema/mvc 
        http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
        http://www.springframework.org/schema/tx 
        http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
        http://www.springframework.org/schema/util
        http://www.springframework.org/schema/util/spring-util-4.0.xsd">

	<!--后期放开，生产环境只需要引用spring-mybatis.xml-->
	<!--<import resource="spring-mybatis.xml"></import>-->
    <import resource="spring-context.xml"></import>
    <!-- 领取工单任务后的aop-->
    <bean id="takeWorkflowTaskAspect" class="com.suninfo.aop.TakeWorkflowTaskAspect"/>
    <aop:config>
        <aop:pointcut id="takeWorkflowTaskPointcut" expression="execution(*  com.suninfo.workflow.WorkFlowService.takeTask(..))" />
        <aop:advisor pointcut-ref="takeWorkflowTaskPointcut" advice-ref="takeWorkflowTaskAspect"   />
    </aop:config>
    <!--流程activiti相关配置-->
    <!-- spring负责创建流程引擎的配置文件 -->
	<bean id="processEngineConfiguration" class="org.activiti.spring.SpringProcessEngineConfiguration">
		<property name="history" value="full"/>
		<!-- 数据源 -->
		<property name="dataSource" ref="dataSource" />
		<!-- 配置事务管理器，统一事务 -->
		<property name="transactionManager" ref="transactionManager" />
		<!-- 设置建表策略，如果没有表，自动创建表 -->
		<property name="databaseSchemaUpdate" value="true" />
		<!-- 是否启动jobExecutor -->
		<property name="jobExecutorActivate" value="false" />

		<property name="eventListeners">
			<list>
				<ref bean="globalEventListener"/>
			</list>
		</property>
		<!--自动部署流程定义 -->
        <!--<property name="deploymentResources" value="classpath*:/workflow/*.bpmn" />-->
	</bean>
	<bean id="processEngine" class="org.activiti.spring.ProcessEngineFactoryBean">
		<property name="processEngineConfiguration" ref="processEngineConfiguration" />
	</bean>
    <!--流程通知listener -->
    <bean id="noticeTaskListener" class="com.suninfo.event.NoticeTaskListener"/>
    <!--流程业务处理listener -->
    <bean id="dealBusinessListener" class="com.suninfo.event.DealBusinessListener"/>
	<!-- 流程引擎全局事件处理器-->
	<bean id="globalEventListener" class="com.suninfo.event.GlobalEventListener">
		<property name="handlers">
			<map>
				<entry key="TASK_CREATED" value="noticeTaskListener"/>
				<entry key="TASK_COMPLETED" value="dealBusinessListener"/>
			</map>
		</property>
	</bean>

	<!-- 创建activiti提供的各种服务 -->
	<!-- 工作流仓储服务 -->
	<bean id="repositoryService" factory-bean="processEngine" factory-method="getRepositoryService" />
	<!-- 工作流运行服务 -->
	<bean id="runtimeService" factory-bean="processEngine" factory-method="getRuntimeService" />
	<!-- 工作流任务服务-->
	<bean id="taskService" factory-bean="processEngine" factory-method="getTaskService" />
	<!-- 工作流历史数据服务-->
	<bean id="historyService" factory-bean="processEngine" factory-method="getHistoryService" />
	<!-- 工作流管理服务-->
	<bean id="managementService" factory-bean="processEngine" factory-method="getManagementService" />
	<bean id="formService" factory-bean="processEngine" factory-method="getFormService" />
	<!-- 工作流唯一服务 -->
	<bean id="IdentityService" factory-bean="processEngine" factory-method="getIdentityService"/>


</beans>

spring-context.xml引用了一些mybatis、memcached、api等配置，如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	   xsi:schemaLocation="http://www.springframework.org/schema/beans
 		http://www.springframework.org/schema/beans/spring-beans-4.0.xsd">
        
	<!-- 引入属性文件 -->
	<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">  
        <property name="locations">  
            <list>
                <value>classpath:jdbc.properties</value>
                <value>classpath:memcache.properties</value>
                <value>classpath:mongodb.properties</value>
            </list>
        </property>  
    </bean>


	<import resource="spring-mybatis.xml" />
	<import resource="spring-api.xml" />
	<import resource="spring-memcached.xml" />
	<import resource="spring-mongodb.xml" />
</beans>

spring-api.xml中只是简单的扫描包

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xmlns:tx="http://www.springframework.org/schema/tx"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:context="http://www.springframework.org/schema/context" xmlns:task="http://www.springframework.org/schema/task"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
 		http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
        http://www.springframework.org/schema/aop
        http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.0.xsd
        http://www.springframework.org/schema/mvc
        http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
        http://www.springframework.org/schema/tx
        http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
        http://www.springframework.org/schema/util
        http://www.springframework.org/schema/util/spring-util-4.0.xsd http://www.springframework.org/schema/task http://www.springframework.org/schema/task/spring-task.xsd">

    <context:annotation-config />
    <!-- 自动扫描(自动注入) -->
    <context:component-scan base-package="com.suninfo" />
</beans>

问题分析：

出现这个错误肯定是在类初始化中，而且肯定是WorkflowService这个类导致的，根据spring配置文件的加载顺序。首先是要去加载spring-context.xml这个配置文件的，加载spring-api.xml，进行包扫描，初始化所有注解的bean，当扫描到WorkflowServie时，发现这个类配置了AOP，于是就会去初始化这个TakeWorkflowTaskAspect，而TakeWorkflowTaskAspect这类如下：

public class TakeWorkflowTaskAspect implements AfterReturningAdvice {

    public TakeWorkflowTaskAspect(){
        System.out.println("TakeWorkflowTaskAspect被初始化了");
    }

    @Autowired
    private OperationApproveOrderService opService;
    
     ............................................

OperationApproveOrderService类如下：

@Service("operationApproveOrderService")
public class OperationApproveOrderServiceImpl implements OperationApproveOrderService {

    public OperationApproveOrderServiceImpl(){
        System.out.println("OperationApproveOrderServiceImpl被初始化");
    }

    @Autowired
    private WorkflowOperationApproveDao workflowOperationApproveDao;

    @Autowired
    private WorkFlowService workFlowService;

OperationApproveOrderServiceImpl里面又引用了WorkflowService，看到这里就明白了初始化循环引用的异常。

解决办法：

将spring-context.xml引用放入spring-activit.xml的底部，调整加载顺序

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans" 
	   xmlns:mvc="http://www.springframework.org/schema/mvc"
	   xmlns:aop="http://www.springframework.org/schema/aop" 
	   xmlns:tx="http://www.springframework.org/schema/tx"
	   xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:p="http://www.springframework.org/schema/p"
       xmlns:context="http://www.springframework.org/schema/context" 
       xsi:schemaLocation="
       	http://www.springframework.org/schema/beans
 		http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
        http://www.springframework.org/schema/aop 
        http://www.springframework.org/schema/aop/spring-aop-4.0.xsd
        http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context-4.0.xsd
        http://www.springframework.org/schema/mvc 
        http://www.springframework.org/schema/mvc/spring-mvc-4.0.xsd
        http://www.springframework.org/schema/tx 
        http://www.springframework.org/schema/tx/spring-tx-4.0.xsd
        http://www.springframework.org/schema/util
        http://www.springframework.org/schema/util/spring-util-4.0.xsd">

	<!--后期放开，生产环境只需要引用spring-mybatis.xml-->
	<!--<import resource="spring-mybatis.xml"></import>-->
    <!-- 领取工单任务后的aop-->
    <bean id="takeWorkflowTaskAspect" class="com.suninfo.aop.TakeWorkflowTaskAspect"/>
    <aop:config>
        <aop:pointcut id="takeWorkflowTaskPointcut" expression="execution(*  com.suninfo.workflow.WorkFlowService.takeTask(..))" />
        <aop:advisor pointcut-ref="takeWorkflowTaskPointcut" advice-ref="takeWorkflowTaskAspect"   />
    </aop:config>
    <!--流程activiti相关配置-->
    <!-- spring负责创建流程引擎的配置文件 -->
	<bean id="processEngineConfiguration" class="org.activiti.spring.SpringProcessEngineConfiguration">
		<property name="history" value="full"/>
		<!-- 数据源 -->
		<property name="dataSource" ref="dataSource" />
		<!-- 配置事务管理器，统一事务 -->
		<property name="transactionManager" ref="transactionManager" />
		<!-- 设置建表策略，如果没有表，自动创建表 -->
		<property name="databaseSchemaUpdate" value="true" />
		<!-- 是否启动jobExecutor -->
		<property name="jobExecutorActivate" value="false" />

		<property name="eventListeners">
			<list>
				<ref bean="globalEventListener"/>
			</list>
		</property>
		<!--自动部署流程定义 -->
        <!--<property name="deploymentResources" value="classpath*:/workflow/*.bpmn" />-->
	</bean>
	<bean id="processEngine" class="org.activiti.spring.ProcessEngineFactoryBean">
		<property name="processEngineConfiguration" ref="processEngineConfiguration" />
	</bean>
    <!--流程通知listener -->
    <bean id="noticeTaskListener" class="com.suninfo.event.NoticeTaskListener"/>
    <!--流程业务处理listener -->
    <bean id="dealBusinessListener" class="com.suninfo.event.DealBusinessListener"/>
	<!-- 流程引擎全局事件处理器-->
	<bean id="globalEventListener" class="com.suninfo.event.GlobalEventListener">
		<property name="handlers">
			<map>
				<entry key="TASK_CREATED" value="noticeTaskListener"/>
				<entry key="TASK_COMPLETED" value="dealBusinessListener"/>
			</map>
		</property>
	</bean>

	<!-- 创建activiti提供的各种服务 -->
	<!-- 工作流仓储服务 -->
	<bean id="repositoryService" factory-bean="processEngine" factory-method="getRepositoryService" />
	<!-- 工作流运行服务 -->
	<bean id="runtimeService" factory-bean="processEngine" factory-method="getRuntimeService" />
	<!-- 工作流任务服务-->
	<bean id="taskService" factory-bean="processEngine" factory-method="getTaskService" />
	<!-- 工作流历史数据服务-->
	<bean id="historyService" factory-bean="processEngine" factory-method="getHistoryService" />
	<!-- 工作流管理服务-->
	<bean id="managementService" factory-bean="processEngine" factory-method="getManagementService" />
	<bean id="formService" factory-bean="processEngine" factory-method="getFormService" />
	<!-- 工作流唯一服务 -->
	<bean id="IdentityService" factory-bean="processEngine" factory-method="getIdentityService"/>

    <import resource="spring-context.xml"></import>

</beans>