using a <jee:jndi-lookup string inside an instance of PropertyPlaceholderConfigurer - spring

Question

Environment: Windows server 2003, Spring 3.0, Tomcat 6
How can I reference a JNDI property inside a PropertyPlaceholderConfigurer?
Specifically, I'm using JNDI to look up a java.lang.String that represents a path to
a property file needed by my webapp
<jee:jndi-lookup id="mypropsfile1" jndi-name="myPropsFile1" resource-ref="true"/>
<jee:jndi-lookup id="mypropsfile2" jndi-name="myPropsFile2" resource-ref="true"/>
<bean id="propertyConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="ignoreUnresolvablePlaceholders" value="true"/>
<property name="locations">
<array>
<value>how to use mypropsfile1 here ??</value>
<value>how to use mypropsfile2 here ??</value>
</array>
</property>
</bean>
My "jee:jndi-lookup"s are working AFAIK. My problem seems to be how to reference JNDI resources
inside the tag pair
Thanks in advance!
Mark

Answer 1

Your approach may not work Mark, this is because PropertyPlaceHolderConfigurer is a BeanFactoryPostProcessor and gets invoked at the point when the bean definitions are created, whereas the jndi lookup happens post this stage.
I saw an older Spring forum discussion item, which has a recommendation for an approach of using a jndi lookup based properties file, which may suit your needs:

Answer 2

I believe you will have to do something like this . I haven't tested it but basically the setLocations method in PropertyPlaceholderConfigurer takes in an array of Resource(In our case UrlResource - http://static.springsource.org/spring/docs/2.0.x/api/org/springframework/core/io/UrlResource.html) which in turn has a constructor with the file path .
<jee:jndi-lookup id="mypropsfile1" jndi-name="myPropsFile1" default-value="file:///C:/defaultPath" resource-ref="true"/>
<jee:jndi-lookup id="mypropsfile2" jndi-name="myPropsFile2" resource-ref="true"/>
<bean id="propertyConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer" depends-on="mypropsfile1,mypropsfile2">
<property name="ignoreUnresolvablePlaceholders" value="true"/>
<property name="locations">
<list>
<bean class="org.springframework.core.io.UrlResource">
<constructor-arg><ref bean="mypropsfile1"/></constructor-arg>
</bean>
<bean class="org.springframework.core.io.UrlResource">
<constructor-arg><ref bean="myPropsFile2"/></constructor-arg>
</bean>
</list>
</property>
</bean>
I am not sure if there is a tag called in spring . Check this http://static.springsource.org/spring/docs/3.0.x/spring-framework-reference/html/beans.html#beans-introduction

Answer 3

I do this in Spring 3 using a map as follows:
<jee:jndi-lookup id="myJndiLookup" jndi-name="com.techtrip.spring.config.myJndiLookup"></jee:jndi-lookup>
<bean id="somethingWithMap" class="com.techtrip.foo.SomethingWithMap">
<property name="propMap">
<map>
<entry key="myJndiLookup" value-ref="myJndiLookup" />
</map>
</property>
</bean>
This works fine in most cases. You may run into trouble if you use AOP or something that wraps the bean in a Proxy class even if you set eager init correctly. A solution in that case is to directly access the somethingWithMap bean from the app context when needed using:
applicationContext.getBeansOfType(type, includeNonSingletons, allowEagerInit);
*Note that this will return a Map<String, T> where you can access the bean by name.

Answer 4

Not exactly for a single JNDI property, this is using a Properties reference instead, obtained through JNDI:
<!-- Lookup Properties reference through JNDI -->
<jee:jndi-lookup id="config-properties" jndi-name="resources/resource-name" resource-ref="true"/>
<bean id="propertyConfigurer"
class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer" depends-on="config-properties">
<property name="ignoreUnresolvablePlaceholders" value="true"/>
<!-- Once the reference is obtained from JNDI, it can be used like any other reference -->
<property name="properties" ref="config-properties"></property>
</bean>