Trouble integrating a library using Apache Commons Config with Spring project using PropertyPlaceholderConfigurer

Question

I have a custom library that sends a JMS notification. The idea is that you can use the library by simply by setting some properties in your project.

The custom library is using the Apache Commons Configuration. (The reason I mention this is that I suspect it may be playing a role in my problem). I'm trying to use it in my current Spring project which doesn't use Commons Config but uses the PropertyPlaceholderConfigurer. I've got the properties I need written out in a .properties file.

I've added the library as a dependency in my pom.xml file. I tried adding it into my web.xml like so

<context-param>
<param-name>contextConfigLocation</param-name>
    <param-value>
    ...
    classpath:mylibrary-context.xml
    </param-value>
</context-param>

When creating a bean in my Spring project, I tried to reference one of the beans defined in the library, so I could use it. There's an error creating one of the library beans that requires a property from my properties file.

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'libraryBean' defined in class path resource [mylibrary-context.xml]: Initialization of bean failed; nested exception is org.springframework.beans.TypeMismatchException: Failed to convert property value of type 'java.lang.String' to required type 'boolean' for property 'useCompression'; nested exception is java.lang.IllegalArgumentException: Invalid boolean value [${foo.bar.use.compression}]

I know some of the other properties files in the project have boolean properties set the exact same way without issue. Here is how I'm loading the properties files in the applicationContext.xml(which after checking the logs, seems to load correctly)

<bean id="propertyPlaceholderConfigurer"
    class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
  <list>
    ...
    <!-- loaded in order-->
    <value>classpath:foo/bar/some-props.properties</value>
    <value>classpath:foo/bar/some-monitoring.properties</value>
    <value>file:/${user.home}/foo/bar/some-monitoring.properties</value>
    <value>file:/etc/foo/bar/some-monitoring.properties</value>
  </list>
</property>
<property name="ignoreResourceNotFound" value="true"/>
<property name="ignoreUnresolvablePlaceholders" value="true"/>

and finally my some-monitoring.properties file:

foo.bar.use.compression=true
foo.bar.name=foobar
foo.bar.broker.url=someurl

So I'm just wondering what's going on with the boolean property and why? If its a general problem with the PropertyPlaceholderConfigurer not loading boolean properties, its odd that I'm not having a problem with the other properties files. Is it that there is some conflict because of the library using the Commons Configuration? My knowledge of how Spring loads up these properties is pretty shallow so this seems like a chance to get a better handle on what's going on under the covers.

If anyone can shed some light on what's going on and how to fix/get around it, any help is greatly appreciated!

Answer 1

Quoting Jurgen on the spring-dev list:

PropertyPlaceholderConfigurer is an implementation of the BeanFactoryPostProcessor interface: This interface and its sibling BeanPostProcessor just apply to the BeanFactory that defines them, that is, to the application context that defines them.

If you combine multiple config files into a single contextConfigLocation, a PropertyPlaceholderConfigurer defined in any of the files will apply to all of the files, because they are loaded into a single application context.

As far as I understand, you tried to combine all your application contexts into the contextConfigLocation. According to the quotation, it should work fine. I think that you have other kind of problem. In my opinion both boolean and string properties are not loaded at all. Maybe it seems as string properties are loaded, but I think that their values are set to ${foo.bar.name} and ${foo.bar.broker.url}. Since they are Strings, they can hold these values. When Spring tries to set ${foo.bar.use.compression} to the boolean, you have typecast problem which just reveals wider issue.

Probably, if you set:

<property name="ignoreResourceNotFound" value="false"/>
<property name="ignoreUnresolvablePlaceholders" value="false"/>

you will see that PropertyPlaceHolderConfigurer cannot resolve your properties files.

Please also try using classpath*: notation when you refer to resources from other JARs.