SSI报空指针异常，即spring注入失败问题的解决方式

本方法的前提是配置文件没有问题，但却报空指针异常

我的配置文件如下：

<?xml version="1.0" encoding="UTF-8"?>
<beans
 xmlns="https://www.springframework.org/schema/beans"
 xmlns:xsi="https://www.w3.org/2001/XMLSchema-instance"
 xmlns:aop="https://www.springframework.org/schema/aop"
 xmlns:tx="https://www.springframework.org/schema/tx"
 
 xsi:schemaLocation="https://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans-2.0.xsd
        https://www.springframework.org/schema/aop https://www.springframework.org/schema/aop/spring-aop-2.0.xsd
           https://www.springframework.org/schema/tx https://www.springframework.org/schema/tx/spring-tx-2.0.xsd">



    <bean id="dataSource"
      class="org.apache.commons.dbcp.BasicDataSource"
      destroy-method="close">
      <property name="driverClassName" value="oracle.jdbc.driver.OracleDriver" />
      <property name="url"
       value="jdbc:oracle:thin:@localhost:1521:orcl" />
      <property name="username" value="system" />
      <property name="password" value="+1101+" />
     </bean>
    
     <!-- spring的ibatis 配制 -->
    <bean id="sqlMapClient"
        class="org.springframework.orm.ibatis.SqlMapClientFactoryBean">
        <property name="configLocation" value="classpath:/sqlMapConfig.xml" />
        <property name="dataSource" ref="dataSource" />
    </bean>
    
    <!-- spring 的事务处理类配置 -->
    <bean id="transactionManager"
        class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
        <property name="dataSource">
            <ref local="dataSource" />
        </property>
    </bean>
    
    <!-- 实体DAO类  -->
    <bean id="userDAO" class="test.UserDAO">
        <property name="sqlMapClient">
            <ref local="sqlMapClient" />
        </property>
    </bean>
    
    
    <!-- Struts2 action类 -->
    <bean id="user" class="test.User" >
        <property name="userdao">
            <ref bean="userDAOProxy"/>
        </property>
    </bean>
    
    
    <bean id="name" class="test.User">
        <property name="name" value="张大三"/>
    </bean>


    
    <!-- 实体DAO类的代理类 -->
    <bean id="userDAOProxy"  
        class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean">
        <property name="transactionManager">
            <ref bean="transactionManager" />
        </property>
        <property name="target">
            <ref local="userDAO" />
        </property>
        <property name="transactionAttributes">
            <props>
                <prop key="insert*">PROPAGATION_REQUIRED</prop>
                <prop key="select*">PROPAGATION_REQUIRED</prop>
                <prop key="delete*">PROPAGATION_REQUIRED</prop>
                <prop key="update*">PROPAGATION_REQUIRED</prop>
                <prop key="get*">PROPAGATION_REQUIRED,readOnly</prop>
            </props>
        </property>
    </bean>
</beans>



<?xml ve