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I've learnt that I can provide Spring with a <context:property-placeholder> element, which appears to use a PropertyPlaceholderConfigurer to interpolate variables (i.e. replace tokens like ${foo}) against a properties file.

Is there a way to customize the class that's used for resolving the tokens? In particular, I'd quite like to use an Apache Commons Config Configuration object to provide the values of the tokens, rather than using a properties file.

bacar
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  • [org.springframework.core.env.PropertyResolver](http://static.springsource.org/spring/docs/3.1.0.RELEASE/javadoc-api/org/springframework/core/env/PropertyResolver.html) looks promising, but the javadoc doesn't really explain how to use it and it's not mentioned in the [3.1 release reference documentation](http://static.springsource.org/spring/docs/3.1.0.RELEASE/reference/htmlsingle/). – bacar Aug 16 '12 at 10:45

1 Answers1

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Yes, subclass PropertyPlaceholderConfigurer and override the loadProperties method. This method is passed a Properties object which you can fill with values however you wish. Alternatively, you can define an alternative implementation of PropertiesPersister and plug that into a normal PropertyPlaceholderConfigurer.

In Spring 3.1 you can pull values directly from your commons configuration object by creating your own PropertySource implementation, and registering it with the application context, typically by using an ApplicationContextInitializer. This blog post provides a good overview of the process. <context:property-placeholder> in Spring 3.1 will pull values from registered PropertySources as well as from any properties files you specify.

Ian Roberts
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  • And then do what with this class? Presumably I have to tell my spring configuration about it in some way. – bacar Aug 16 '12 at 11:04
  • Is there a non-`Properties` object based implementation? Commons `Configuration` interface is not a subclass of `Properties` - I may have to subclass Properties such that it wraps Configuration. – bacar Aug 16 '12 at 11:06
  • In Spring 3.1 yes, I've edited my answer with a link to a useful blog post. – Ian Roberts Aug 16 '12 at 11:55
  • Part I was very useful as I'm writing a standalone app. However it doesn't mention (though @Ian does!) that you need to add `` to get it to work! – bacar Aug 16 '12 at 17:22