将参数传递给Spring中构造函数中引用的Bean

Question

I want to pass a parameter to a bean referenced from another bean in Spring Context.xml. Is it even possible ?

NOTE : The DISCARD bean would have different values when referenced from different beans.

<bean id="dropBadTimestampFilter" class="TimestampRangeMatcherModifier">
    <constructor-arg index="0" value="_TIME"/>
    <constructor-arg index="1" ref="DISCARD" /> <!--Want to pass a prameter value to this-->
</bean>

<bean id="DISCARD" class="SettingModifier">
     <property name="fields">
         <map>
             <entry key="_ORG" value="CONSTANT"/>
             <entry key="CAUSE" value="______"/>  <!-- Want to be passed from bean referring it-->
         </map>
    </property>
</bean>

Is there a way that we could have a reference of bean using a bean using Spring Expression Language so that the following is possible :

<bean id="DISCARD" class="SettingModifier">
     <property name="fields">
         <map>
             <entry key="_ORG" value="CONSTANT"/>
             <entry key="CAUSE" value="#{dropBadTimestampFilter.CAUSE}"/>  <!-- Can this bean get reference of all the beans using it and not only dropBadTimestampFilter. -->
         </map>
    </property>
</bean>

Answer 1

Basically you've to make that bean a prototype bean, if it has different properties for different injection. And then, set the value for "CAUSE" key in a @PostConstruct method, of TimestampRangeMatcherModifier bean. In XML, you define such method using init-method attribute of bean tag.

Another approach would be by declaring the bean in-place, like this:

<bean id="dropBadTimestampFilter" class="TimestampRangeMatcherModifier">
    <constructor-arg index="0" value="_TIME"/>
    <constructor-arg index="1">
        <bean class="SettingModifier"> <!-- no need of id here -->
            <property name="fields">
                <map>
                   <entry key="_ORG" value="CONSTANT"/>
                   <entry key="CAUSE" value="______"/>
               </map>
            </property>
        </bean>
    </constructor-arg>
</bean>