@Value and PropertyPlaceholderConfigurer

[jhaile]

In Spring 2.5 we used a PropertyPlaceholderConfigurer to load up property files and inject the property values into beans using XML.

We're trying to migrate to Spring 3.0 M2, and would like to use @Value to accomplish something similar. What would be the correct approach to do something similar to PropertyPlaceholderConfigurer?

Can an @Value annotation access properties loaded by PropertyPlaceholderConfiguerer? Should we setup a separate PropertiesFactoryBean and inject from that (what's the syntax to do that?)?

Any advice would be appreciated!
-Jeremy

[Chris Beams]

You actually won't need PropertyPlaceholderConfigurer if you're using @Value.

You could do just the following:

Given a properties file on the classpath at 'com/acme/app/myprops.properties':

hostname=localhost
foo=a
bar=b

In your XML, declare a utilroperties bean

<util:properties id="myProps" location="classpath:com/acme/app/myprops.properties"/>

Then, within your classes:

@Value("#{myProps.hostname}")
public void setHostName(String hostname) {
    this.hostname = hostname;
}

Spring EL can resolve any bean by its name. Since the content of your properties file is now available as a Spring-managed java.util.Properties bean named 'myProps', you can just refer to it by name.


I've just added a unit test that captures the scenario above: https://fisheye.springsource.org/cha...k/trunk?cs=874

Also note that in the forthcoming M3 release (drops this week!), you'll be able to use 'regular' ${...} tokens with @Value, and these will resolve using PropertyPlaceholderConfigurer / <contextroperty-placeholder/>. So you've got two options. The ${...} style is processed once and only once, during BeanFactoryPostProcessing, and the #{...} style is evaluated every time a bean is instantiated. So you can think of one as static and the other as dynamic.

[jhaile]

Thanks Chris.

I apologize for the cross-posting, but had already created a topic in Core Container since I accidentally posted in JavaConfig at first.

This topic contains a more detailed description of the problems I've encountered in using property files:
http://forum.springframework.org/sho...lderconfigurer

Could you please reply to the issues in that topic?