Using multiple property files (via PropertyPlaceholderConfigurer) in multiple projects/modules

Question

We are currently writing an application which is split into multiple projects/modules. For example, let\'s take the following modules:

• myApp-DAO
• myApp

Answer 1

I tried the solution below, it works on my machine.

<context:property-placeholder location="classpath*:connection.properties" ignore-unresolvable="true" order="1" />

<context:property-placeholder location="classpath*:general.properties" order="2"/>

In case multiple elements are present in the Spring context, there are a few best practices that should be followed:

the order attribute needs to be specified to fix the order in which these are processed by Spring all property placeholders minus the last one (highest order) should have ignore-unresolvable=”true” to allow the resolution mechanism to pass to others in the context without throwing an exception

source: http://www.baeldung.com/2012/02/06/properties-with-spring/

Answer 2

The PropertiesPlaceholderConfigurer bean has an alternative property called "propertiesArray". Use this instead of the "properties" property, and configure it with an <array> of property references.

Answer 3

You can have multiple <context:property-placeholder /> elements instead of explicitly declaring multiple PropertiesPlaceholderConfigurer beans.

Answer 4

If you ensure that every place holder, in each of the contexts involved, is ignoring unresolvable keys then both of these approaches work. For example:

<context:property-placeholder
location="classpath:dao.properties,
          classpath:services.properties,
          classpath:user.properties"
ignore-unresolvable="true"/>

or

    <bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="locations">
            <list>
                <value>classpath:dao.properties</value>
                <value>classpath:services.properties</value>
                <value>classpath:user.properties</value>
            </list>
        </property> 
        <property name="ignoreUnresolvablePlaceholders" value="true"/>
    </bean>

Answer 5

I know that this is an old question, but the ignore-unresolvable property was not working for me and I didn't know why.

The problem was that I needed an external resource (something like location="file:${CATALINA_HOME}/conf/db-override.properties") and the ignore-unresolvable="true" does not do the job in this case.

What one needs to do for ignoring a missing external resource is:

ignore-resource-not-found="true"

Just in case anyone else bumps into this.