如何将一个 spring bean 的父属性设置为另一个 bean 的属性？

Question

Is it possible to use the property of one Spring bean to set the parent attribute of another bean?

As background info, I'm trying to change a project to use a container-provided data source without making huge changes to the Spring config.

Simple class with a property I want to use

package sample;

import javax.sql.DataSource;

public class SpringPreloads {

    public static DataSource dataSource;

    public DataSource getDataSource() {
        return dataSource;
    }

    //This is being set before the Spring application context is created
    public void setDataSource(DataSource dataSource) {
        SpringPreloads.dataSource = dataSource;
    }

}

Relevant bits of spring beans configuration

<!-- new -->
<bean id="springPreloads" class="sample.SpringPreloads" />

<!-- How do I set the parent attribute to a property of the above bean? -->
<bean id="abstractDataSource" class="oracle.jdbc.pool.OracleDataSource" 
abstract="true" destroy-method="close" parent="#{springPreloads.dataSource}">
    <property name="connectionCachingEnabled" value="true"/>
    <property name="connectionCacheProperties">
        <props>
            <prop key="MinLimit">${ds.maxpoolsize}</prop>
            <prop key="MaxLimit">${ds.minpoolsize}</prop>
            <prop key="InactivityTimeout">5</prop>
            <prop key="ConnectionWaitTimeout">3</prop>
        </props>
    </property>
</bean>

Exception when tested

org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named '#{springPreloads.dataSource}' is defined

or if I remove the Spring EL from the above I get this:

org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'springPreloads.dataSource' is defined

Answer 1

I think this is what you're after. The springPreloads bean is used as a "factory", but only to get hold of its dataSource attribute, which is then plugged with various properties...

I'm guessing springPreloads.dataSource is an instance of oracle.jdbc.pool.OracleDataSource?

<bean id="springPreloads" class="sample.SpringPreloads" />

<bean id="abstractDataSource" factory-bean="springPreloads" factory-method="getDataSource">
    <property name="connectionCachingEnabled" value="true" />
    <property name="connectionCacheProperties">
        <props>
            <prop key="MinLimit">${ds.maxpoolsize}</prop>
            <prop key="MaxLimit">${ds.minpoolsize}</prop>
            <prop key="InactivityTimeout">5</prop>
            <prop key="ConnectionWaitTimeout">3</prop>
        </props>
    </property>
</bean>