Null Pointer Exception - spring 3

Question

I am using the below statement in my applicationContext.xml file (Spring 3).

<bean name="loggingAutoProxy"
      class="org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator"> 

In this applicationContext file, when i try to give a different name for the bean property name and reference, it is returning null object. But, if i give a same value for the name and reference, it is working properly/ returning the bean reference correctly. Is this problem because of the org.springframework.aop.framework.autoproxy.BeanNameAutoProxyCreator ? If yes, how to resolve this issue?

This doesn't work (returns the bean reference as null in my java code):

<bean id="cacheDelegate" class="com.srsa.wiradmin.delegate.CacheDelegate" > 
<property name="statusDBDAO"><ref bean="BMOStatusDBDAO" /></property> 
</bean> 

 <bean id="BMOStatusDBDAO" class="com.srsa.wiradmin.dao.StatusDBDAO">
        <property name="dataSource">
            <ref bean="BMOAdminDataSource" />
        </property>
</bean>
    <bean id="BMOAdminDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" 
                    destroy-method="close" lazy-init="default" autowire="default" dependency-check="default">
            <property name="driverClass" value="${jdbc.driver}" ></property>
            <property name="jdbcUrl" value="${admin.jdbc.url}" ></property>
            <property name="user" value="${admin.jdbc.user}" ></property>
            <property name="password" value="${admin.jdbc.password}" ></property>
            <property name="initialPoolSize" value="3" ></property>
            <property name="minPoolSize" value="3" ></property>
            <property name="maxPoolSize" value="25" ></property>
            <property name="acquireIncrement" value="1" ></property>
            <property name="acquireRetryDelay" value="1000" ></property>
            <property name="debugUnreturnedConnectionStackTraces" value="true" ></property>
            <property name="maxIdleTime" value="300" ></property>
            <property name="unreturnedConnectionTimeout" value="300000" ></property>
            <property name="preferredTestQuery" value="SELECT COUNT(*) FROM LOCALE_CODE" ></property>
            <property name="checkoutTimeout" value="300000" ></property>
            <property name="idleConnectionTestPeriod" value="600000" ></property>
</bean>

This works (returns the object properly):

<bean id="cacheDelegate" class="com.srsa.wiradmin.delegate.CacheDelegate" > 
<property name="statusDBDAO"><ref bean="statusDBDAO" /></property> 
</bean> 

 <bean id="statusDBDAO" class="com.srsa.wiradmin.dao.StatusDBDAO">
        <property name="dataSource">
            <ref bean="BMOAdminDataSource" />
        </property>
</bean>

    <bean id="BMOAdminDataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource" 
                    destroy-method="close" lazy-init="default" autowire="default" dependency-check="default">
            <property name="driverClass" value="${jdbc.driver}" ></property>
            <property name="jdbcUrl" value="${admin.jdbc.url}" ></property>
            <property name="user" value="${admin.jdbc.user}" ></property>
            <property name="password" value="${admin.jdbc.password}" ></property>
            <property name="initialPoolSize" value="3" ></property>
            <property name="minPoolSize" value="3" ></property>
            <property name="maxPoolSize" value="25" ></property>
            <property name="acquireIncrement" value="1" ></property>
            <property name="acquireRetryDelay" value="1000" ></property>
            <property name="debugUnreturnedConnectionStackTraces" value="true" ></property>
            <property name="maxIdleTime" value="300" ></property>
            <property name="unreturnedConnectionTimeout" value="300000" ></property>
            <property name="preferredTestQuery" value="SELECT COUNT(*) FROM LOCALE_CODE" ></property>
            <property name="checkoutTimeout" value="300000" ></property>
            <property name="idleConnectionTestPeriod" value="600000" ></property>
</bean>

bye....

Answer 1

您的cacheDelegate bean正在查找一个引用到ID statusDBDAO的bean，但DAO上的ID实际上是BMOStatusDBDAO 。