Question

I have Java classes like this:

public class Config {
    public Config1 getConfigOpt1();
    public Config2 getConfigOpt2();
}

public class SomeBean {
    public Config getEntireConfig();
}

public class BeanToConstruct {

    public static BeanToConstruct createAndStart( Config1 config1, Config2 config2 )
}

Given SomeBean, I would construct BeanToConstruct like this:

SomeBean someBean = ....
BeanToConstruct bean = BeanToConstruct.createAndStart( 
    someBean.getEntireConfig().getConfigOpt1(),
    someBean.getEntireConfig().getConfigOpt2() )

How can I do this inside my applicationContext.xml? This is basically what I want to do, but it obviously doesn’t work. I could pull the entire Config object out into its own bean, but I don’t want to have this extra bean around that is really only needed to make constructing BeanToConstruct possible.

<bean class="com.example.SomeBean" id="someBean"/>
<bean class="com.example.BeanToConstruct" factory-method="createAndStart" id="myBean">
    <constructor-arg>
        <bean factory-bean="someBean" factory-method="getEntireConfig().getConfigOpt1()"/>
    </constructor-arg>
    <constructor-arg>
        <bean factory-bean="someBean" factory-method="getEntireConfig().getConfigOpt2()"/>
    </constructor-arg>
</bean> 

Answer 1

In Spring 3.x you may use expression language:

<bean class="com.example.BeanToConstruct" factory-method="createAndStart" id="myBean"> 
    <constructor-arg value = "#{someBean.entireConfig.configOpt1}" /> 
    <constructor-arg value = "#{someBean.entireConfig.configOpt2}" /> 
</bean>