相同Bean分别被Spring MVC子容器与Spring父容器初始化，导致@Value注入失败

在车保养项目开发过程中，技术架构：Spring MVC + MyBatis；Service层接口中属性，如果使用注解@Value注入，不能够拿到Properties文件中拿到对应的key值；但在Spring配置文件applicationContext-xxx.xml文件中配置的Properties就可以拿到。具体项目中相关代码如下：

Spring MVC的dispatcher-servlet.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop.xsd">

    <!-- 自定义的参数解析器放在第一位置 -->
    <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
        <!-- 自定义参数解析器 -->
        <property name="customArgumentResolvers">
            <list>
                <bean class="com.qding.base.resolver.ArgumentFromJsonResolver" />
            </list>
        </property>
    </bean>

    <!-- 开启组件扫描 -->
    <!-- 对包中的所有类进行扫描，以完成Bean创建和自动依赖注入的功能 -->
    <context:component-scan base-package="com.qding"/>

    <!-- 开启注解 -->
    <mvc:annotation-driven />

    <!-- 启用AspectJ对Annotation的支持 -->
    <aop:aspectj-autoproxy proxy-target-class="true"/>

    <!-- 静态资源路径 -->
    <mvc:resources location="/easyui/" mapping="/easyui/**"/>
    <mvc:resources location="/js/" mapping="/js/**"/>
    <mvc:resources location="/html/" mapping="/html/**"/>

    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
        <property name="prefix" value="/WEB-INF/views/"/>
        <property name="suffix" value=".jsp" />
    </bean>

    <!-- 配置多请求数据类型，如json xml-->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!-- set the max upload size10MB -->
        <property name="defaultEncoding" value="UTF-8" />
        <property name="maxUploadSize" value="10485760" />
        <property name="maxInMemorySize" value="10240" />
    </bean>

    <!-- 配置Controller拦截器 -->
    <mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/**" />
            <mvc:exclude-mapping path="/remote/imessage"/>
            <mvc:exclude-mapping path="/easyui/**"/>
            <mvc:exclude-mapping path="/js/**"/>
            <mvc:exclude-mapping path="/html/**"/>
            <bean class="com.qding.base.interceptor.TransferSecurityInterceptor"/>
        </mvc:interceptor>
        <mvc:interceptor>
            <mvc:mapping path="/**" />
            <mvc:exclude-mapping path="/remote/imessage"/>
            <mvc:exclude-mapping path="/easyui/**"/>
            <mvc:exclude-mapping path="/js/**"/>
            <mvc:exclude-mapping path="/html/**"/>
            <bean class="com.qding.doc.interceptor.TransferDocInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>

    <!-- 切面配置：Controller方法参数校验 -->
    <bean class="com.qding.base.aspect.ParameterValidateAspect" />
</beans>

Spring的applicationContext-service.xml文件：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:task="http://www.springframework.org/schema/task"
       xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd
    http://www.springframework.org/schema/task
    http://www.springframework.org/schema/task/spring-task.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop.xsd
    http://www.springframework.org/schema/tx
    http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!-- 开启组件扫描 -->
    <!-- 对包中的所有类进行扫描，以完成Bean创建和自动依赖注入的功能 -->
    <context:component-scan base-package="com.qding.*.*.service"/>

    <!-- 定时任务 -->
    <task:annotation-driven/>

    <!-- 启用AspectJ对Annotation的支持 -->
    <aop:aspectj-autoproxy/>

    <!-- Transaction Support -->
    <tx:advice id="useTxAdvice" transaction-manager="txManager">
        <tx:attributes>
            <tx:method name="*remove*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception"/>
            <tx:method name="*save*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />
            <tx:method name="*modify*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />
            <tx:method name="*update*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />
            <tx:method name="create*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />
            <tx:method name="fill*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />
            <tx:method name="cancel*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />
            <tx:method name="*chang*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />

            <tx:method name="find*" propagation="SUPPORTS"/>
            <tx:method name="get*" propagation="SUPPORTS"/>
            <tx:method name="query*" propagation="SUPPORTS"/>
            <tx:method name="page*" propagation="SUPPORTS"/>
            <tx:method name="count*" propagation="SUPPORTS"/>
        </tx:attributes>
    </tx:advice>

    <!--把事务控制在Service层-->
    <aop:config>
        <aop:pointcut id="pc" expression="execution(public * com.qding..service.*.*(..))" />
        <aop:advisor pointcut-ref="pc" advice-ref="useTxAdvice" />
    </aop:config>

    <!-- 切面配置：Service层方法执行日志 -->
    <bean class="com.qding.aspect.ServiceVersionLogAspect" />

    <!--memcached客户端配置-->
    <bean name="xmemcachedClientBuilder" class="net.rubyeye.xmemcached.XMemcachedClientBuilder">
        <constructor-arg>
            <list>
                <bean class="java.net.InetSocketAddress">
                    <constructor-arg>
                        <value>${server_1}</value>
                    </constructor-arg>
                    <constructor-arg>
                        <value>${port_1}</value>
                    </constructor-arg>
                </bean>
            </list>
        </constructor-arg>
        <constructor-arg>
            <list>
                <value>${priority_1}</value>
            </list>
        </constructor-arg>
        <property name="connectionPoolSize" value="6"/>
        <property name="commandFactory">
            <bean class="net.rubyeye.xmemcached.command.BinaryCommandFactory"/>
        </property>
        <property name="sessionLocator">
            <bean class="net.rubyeye.xmemcached.impl.KetamaMemcachedSessionLocator"/>
        </property>
        <property name="transcoder">
            <bean class="net.rubyeye.xmemcached.transcoders.SerializingTranscoder" />
        </property>
    </bean>

    <bean name="xmemcachedClient" factory-bean="xmemcachedClientBuilder" factory-method="build" destroy-method="shutdown">
        <property name="opTimeout" value="3000"/>
    </bean>

    <bean id="memCacheUtil" class="com.qding.member.common.cache.MemCacheUtil">
        <!-- 过期时间  单位秒 -->
        <property name="expTime" value="3600"/>
        <!-- 操作失效时间  单位毫秒 -->
        <property name="opTime" value="3000"/>
        <property name="memcachedClient" ref="xmemcachedClient"/>
    </bean>
</beans>

Service层OrderServiceImpl的代码：

public class OrderServiceImpl implements OrderService {
    
        @Value("${bopai.provider_id}")
        private String bopaiProviderId;

        @Value("${bopai.provider_name}")
        private String bopaiProviderName;

        @Value("${bopai.connect.phone}")
        private String boPaiPhone;

        ......
    }

2 排查过程

1. Spring的applicationContext-service.xml文件配置的属性，可以正常拿到Properties文件中的值；【正常】
2. 项目工程的Service层OrderServiceImpl实现，@Value不能拿到Properties文件中的值；【不正常】
3. 代码断点调试： 发现OrderServiceImpl被初始化了两次，第一次@Value可以拿到值，第二次@Value没有拿到值； 【不正常】
4. 发现根本原因： Spring 容器和Spring MVC容器分别都初始化了Service的实例，后者第二次初始化Service实例时，没有拿到@Value值，该实例覆盖掉了Spring 容器初始化的实例；

3 解决方案

通过修改两个配置文件的 <context:component-scan base-package=""/> 扫包范围，达到以下效果：

1. Spring MVC的配置文件dispatcher-servlet严格限制只初始化Controller层实例；
2. Spring的配置文件applicationContext-service.xml严格限制只初始化除Controller层的其他层实例；

修改后的配置文件：

1. Spring MVC的dispatcher-servlet.xml文件 ：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:aop="http://www.springframework.org/schema/aop"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop.xsd">

    <!-- 自定义的参数解析器放在第一位置 -->
    <bean class="org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter">
        <!-- 自定义参数解析器 -->
        <property name="customArgumentResolvers">
            <list>
                <bean class="com.qding.base.resolver.ArgumentFromJsonResolver" />
            </list>
        </property>
    </bean>

    <!-- 开启组件扫描 -->
    <!-- 对包中的所有类进行扫描，以完成Bean创建和自动依赖注入的功能 -->
    <context:component-scan base-package="com.qding.*.*.controller,com.qding.*.controller"/>

    <!-- 开启注解 -->
    <mvc:annotation-driven />

    <!-- 启用AspectJ对Annotation的支持 -->
    <aop:aspectj-autoproxy proxy-target-class="true"/>

    <!-- 静态资源路径 -->
    <mvc:resources location="/easyui/" mapping="/easyui/**"/>
    <mvc:resources location="/js/" mapping="/js/**"/>
    <mvc:resources location="/html/" mapping="/html/**"/>

    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass" value="org.springframework.web.servlet.view.JstlView"/>
        <property name="prefix" value="/WEB-INF/views/"/>
        <property name="suffix" value=".jsp" />
    </bean>

    <!-- 配置多请求数据类型，如json xml-->
    <bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver">
        <!-- set the max upload size10MB -->
        <property name="defaultEncoding" value="UTF-8" />
        <property name="maxUploadSize" value="10485760" />
        <property name="maxInMemorySize" value="10240" />
    </bean>

    <!-- 配置Controller拦截器 -->
    <mvc:interceptors>
        <mvc:interceptor>
            <mvc:mapping path="/**" />
            <mvc:exclude-mapping path="/remote/imessage"/>
            <mvc:exclude-mapping path="/easyui/**"/>
            <mvc:exclude-mapping path="/js/**"/>
            <mvc:exclude-mapping path="/html/**"/>
            <bean class="com.qding.base.interceptor.TransferSecurityInterceptor"/>
        </mvc:interceptor>
        <mvc:interceptor>
            <mvc:mapping path="/**" />
            <mvc:exclude-mapping path="/remote/imessage"/>
            <mvc:exclude-mapping path="/easyui/**"/>
            <mvc:exclude-mapping path="/js/**"/>
            <mvc:exclude-mapping path="/html/**"/>
            <bean class="com.qding.doc.interceptor.TransferDocInterceptor"/>
        </mvc:interceptor>
    </mvc:interceptors>

    <!-- 切面配置：Controller方法参数校验 -->
    <bean class="com.qding.base.aspect.ParameterValidateAspect" />
</beans>

2. Spring的applicationContext-service.xml文件 ：

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns:context="http://www.springframework.org/schema/context"
       xmlns:task="http://www.springframework.org/schema/task"
       xmlns:aop="http://www.springframework.org/schema/aop" xmlns:tx="http://www.springframework.org/schema/tx"
       xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd
    http://www.springframework.org/schema/task
    http://www.springframework.org/schema/task/spring-task.xsd
    http://www.springframework.org/schema/aop
    http://www.springframework.org/schema/aop/spring-aop.xsd
    http://www.springframework.org/schema/tx
    http://www.springframework.org/schema/tx/spring-tx.xsd">

    <!-- 开启组件扫描 -->
    <!-- 对包中的所有类进行扫描，以完成Bean创建和自动依赖注入的功能 -->
    <context:component-scan base-package="com.qding.*.*.service,com.qding.*.*.imessage,com.qding.*.quartz,com.qding.remote.service"/>

    <!-- 定时任务 -->
    <task:annotation-driven/>

    <!-- 启用AspectJ对Annotation的支持 -->
    <aop:aspectj-autoproxy/>

    <!-- Transaction Support -->
    <tx:advice id="useTxAdvice" transaction-manager="txManager">
        <tx:attributes>
            <tx:method name="*remove*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception"/>
            <tx:method name="*save*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />
            <tx:method name="*modify*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />
            <tx:method name="*update*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />
            <tx:method name="create*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />
            <tx:method name="fill*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />
            <tx:method name="cancel*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />
            <tx:method name="*chang*" propagation="REQUIRED" read-only="false" rollback-for="java.lang.Exception" />

            <tx:method name="find*" propagation="SUPPORTS"/>
            <tx:method name="get*" propagation="SUPPORTS"/>
            <tx:method name="query*" propagation="SUPPORTS"/>
            <tx:method name="page*" propagation="SUPPORTS"/>
            <tx:method name="count*" propagation="SUPPORTS"/>
        </tx:attributes>
    </tx:advice>

    <!--把事务控制在Service层-->
    <aop:config>
        <aop:pointcut id="pc" expression="execution(public * com.qding..service.*.*(..))" />
        <aop:advisor pointcut-ref="pc" advice-ref="useTxAdvice" />
    </aop:config>

    <!-- 切面配置：Service层方法执行日志 -->
    <bean class="com.qding.aspect.ServiceVersionLogAspect" />

    <!--memcached客户端配置-->
    <bean name="xmemcachedClientBuilder" class="net.rubyeye.xmemcached.XMemcachedClientBuilder">
        <constructor-arg>
            <list>
                <bean class="java.net.InetSocketAddress">
                    <constructor-arg>
                        <value>${server_1}</value>
                    </constructor-arg>
                    <constructor-arg>
                        <value>${port_1}</value>
                    </constructor-arg>
                </bean>
            </list>
        </constructor-arg>
        <constructor-arg>
            <list>
                <value>${priority_1}</value>
            </list>
        </constructor-arg>
        <property name="connectionPoolSize" value="6"/>
        <property name="commandFactory">
            <bean class="net.rubyeye.xmemcached.command.BinaryCommandFactory"/>
        </property>
        <property name="sessionLocator">
            <bean class="net.rubyeye.xmemcached.impl.KetamaMemcachedSessionLocator"/>
        </property>
        <property name="transcoder">
            <bean class="net.rubyeye.xmemcached.transcoders.SerializingTranscoder" />
        </property>
    </bean>

    <bean name="xmemcachedClient" factory-bean="xmemcachedClientBuilder" factory-method="build" destroy-method="shutdown">
        <property name="opTimeout" value="3000"/>
    </bean>

    <bean id="memCacheUtil" class="com.qding.member.common.cache.MemCacheUtil">
        <!-- 过期时间  单位秒 -->
        <property name="expTime" value="3600"/>
        <!-- 操作失效时间  单位毫秒 -->
        <property name="opTime" value="3000"/>
        <property name="memcachedClient" ref="xmemcachedClient"/>
    </bean>
</beans>

4 问题总结

Spring MVC容器是Spring容器的一个子容器，它同样能够初始化实体类。 由于SpringMVC容器的初始化是在Spring容器初始化之后，所以它会替换Spring中已经存在的类，这样可能会导致冲突 。因此在Spring的配置文件中SpringMVC和Spring容器各司其职，在使用ComponentScan进行扫描时，各自扫描各自的实体类。如下配置：

1. Spring容器扫描配置 ：

<context:component-scan base-package="com.projects.system">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Controller" />         
    </context:component-scan>

2. SpringMVC容器扫描配置 ：

<context:component-scan base-package="com.projects.system">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Service"/>
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
    </context:component-scan>

以上配置在使用Spring xml-based配置时是没有问题的。如果在项目中引入java-base配置时，同时引入了@Configuration注解， @Configuration注解是在Spring容器初始化时进行实体类的初始化工作 ，因此在Spring MVC扫描配置中要将其过滤掉，否则会导致SpringMVC 的rest地址不可访问的问题。新的配置如下：

<context:component-scan base-package="com.projects.system">
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Service"/>
        <context:exclude-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
        <!-- 不扫描配置文件类，避免重复初始化 -->
        <context:exclude-filter type="annotation" expression="org.springframework.context.annotation.Configuration"/>
    </context:component-scan>