PropertyPlaceholder in Java Config HOWTO

[marceloverdijk]

I'm investigating moving from Spring xml config to a Java config.

Currently we use PropertyPlaceholderConfigurer like

<contextroperty-placeholder location="classpath*:META-INF/config.properties,classpath*:META-INF/config-${com.google.appengine.runtime.environment}.proper ties" />

Where ${com.google.appengine.runtime.environment} comes from system property.
So in fact we have a default config.properties which properties might be overridden with properties from e.g. config-Development.properties.

We use this e.g. to set the properties like:

{code}
<bean class="org.springframework.web.context.support.Ser vletContextAttributeExporter">
<property name="attributes">
<map>
<entry key="google.analytics.enabled" value="${google.analytics.enabled}" />
<entry key="google.analytics.webPropertyID" value="${google.analytics.webPropertyID}" />
{code}

Now I'm wondering how we should do this with the new Java Config features?

[Enrico Pizzi]

From the Spring reference documentation, page 109 and following:

@Configuration class-centric use of XML with @ImportResource

In applications where @Configuration classes are the primary mechanism for configuring the container, it will still likely be necessary to use at least some XML. In these scenarios, simply use @ImportResource and define only as much XML as is needed. Doing so achieves a "Java-centric" approach to configuring the container and keeps XML to a bare minimum.

@Configuration
@ImportResource("classpath:/com/acme/properties-config.xml")
public class AppConfig {
private @Value("${jdbc.url}") String url;
private @Value("${jdbc.username}") String username;
private @Value("${jdbc.password}") String password;

public @Bean DataSource dataSource() {
    return new DriverManagerDataSource(url, username, password);
}
}

properties-config.xml
<beans>
<context:property-placeholder location="classpath:/com/acme/jdbc.properties"/>
</beans>

[marceloverdijk]

Thanks Enrico,

I found this page as well but was wondering if I can get rid of XML completely...
As Spring is advertising for Spring 3.1 I believe.

[javapda]

Try the following in 3.1.0 using the new PropertySourcesPlaceholderConfigurer. Notice that the bean is declared static.

    static @Bean public PropertySourcesPlaceholderConfigurer myPropertySourcesPlaceholderConfigurer() {
        PropertySourcesPlaceholderConfigurer p = new PropertySourcesPlaceholderConfigurer();
        Resource[] resourceLocations = new Resource[] {
                new ClassPathResource("my.custom.properties"),
                new ClassPathResource("my.other.properties"),
        };
        p.setLocations(resourceLocations);
        return p;
    }

Example: my.custom.properties:

country.name=Netherlands
city.name=Amsterdam

Then in your spring configuration you can reference ${country.name} and ${city.name} which will subsequently be replaced with 'Netherlands' and 'Amsterdam', respectively.