This post originated from an RSS feed registered with Java Buzz by Chris Winters. Original Post: Multiple, separate PropertyPlaceholderConfigurers in Spring Feed Title: cwinters.com Feed URL: http://www.cwinters.com/search/registrar.php?domain=jroller.com®istrar=sedopark Feed Description: Chris Winters on Java, programming and technology, usually in that order. Latest Java Buzz Posts Latest Java Buzz Posts by Chris Winters Latest Posts From cwinters.com

However, if you want to reference multiple configurers that don't know about each other you'll run into a problem. At first it will appear that you can only define one configurer because some settings won't be replaced properly, but that's a red herring. What happens is that behind the scenes Spring associates each configurer with parsing rules so it knows which configurer is supposed to replace which placeholders. Therefore you've got to provide some disambiguation to this parser. Fortunately it's easy:

    <bean id="appASettings" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
        <property name="location" value="appA_settings.properties" />
        <property name="placeholderPrefix" value="$A{" />
    </bean>
  
    <bean id="appADataSource" 
        class="org.apache.commons.dbcp.BasicDataSource"
        destroy-method="close">
        <property name="driverClassName" value="$A{db.driver}" />
        <property name="url"             value="$A{db.url}" />
        ...

As long as every application has its own prefix its settings will never get stomped on by any other and you can presumably add as many configurers as you need. What's most interesting about this is that the complexity behind this is only revealed if you need it. IMO most open-source projects -- and, to a lesser extent, all software -- have a hard time with this principle, burdening you with lots of configuration to do even simple things.