Read an environment variable from applicationContext.xml

Question

I need read an environment variable defined in my web.xml

<env-entry>
    <description>Path Repositorio NFS</description>
    <env-entry-name>PATH_ENV</env-entry-name>
    <env-entry-type>java.lang.String</env-entry-type>
    <env-entry-value>C:/V3</env-entry-value>
</env-entry>

from my applicationContext.xml

<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location" value="${PATH_ENV}/myprop.properties" />
</bean>

How can I do this ?

---

Finally I have done the next:

1 Define environment variable in context.xml:

<Environment name="PATH_ENV" type="java.lang.String"/>

2 Define env-entry in web.xml

<env-entry>
    <description>Path Repositorio NFS</description>
    <env-entry-name>PATH_ENV</env-entry-name>
    <env-entry-type>java.lang.String</env-entry-type>
    <env-entry-value>/WEB-INF/</env-entry-value>
  </env-entry>

3 Define in applicationContext.xml

<bean id="configurationPath" class="org.springframework.jndi.JndiObjectFactoryBean">  
    <property name="jndiName">  
        <value>java:comp/env/PATH_ENV</value>  
    </property>  
</bean>  

<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
       <property name="location">
            <bean factory-bean="configurationPath" factory-method="concat">
                <constructor-arg value="myprop.properties"/>
            </bean>
        </property>
    </bean>

This is run correctly, However if I define a full path in:

<env-entry-value>C:/V3/</env-entry-value>

I have the next problem:

java.io.FileNotFoundException: Could not open ServletContext resource [/C:/V3/aesantasa.properties]

I cant define a full path in env-entry-value Why?

Answer 1

You can lookup JNDI entries (both environment entries and resources) with the JndiObjectFactoryBean or <jee:jndi-lookup>:

<jee:jndi-lookup id="PATH_ENV" jndi-name="PATH_ENV"/>

(To use the jee-namespace, you must declare it).

That defines a spring bean named "PATH_ENV" that contains (as a string) the path configured int the environment entry. You can now inject it into other beans:

<bean class="xy.Foo">
    <property name="path" ref="PATH_ENV"/>
</bean>

The remaining difficulty is concatenating the strings. (Unfortunately, there is no JndiPlaceholderConfigurer that would replace placeholders with JNDI environment entries, so you can't use the ${property}/foo syntax to concatenate, and must supply yet another bean definition:

<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="location">
        <bean factory-bean="PATH_ENV" factory-method="concat">
            <constructor-arg>/myprop.properties</constructor-arg>
        </bean>
    </property>
</bean>

(code untested as I don't have a Spring project at hand to test it)