Spring @Configuration file with PropertyPlaceholderConfigurer bean doesn't resolve @Value annotation

Question

I have following configuration file:

@Configuration public class PropertyPlaceholderConfigurerConfig {      @Value("${property:defaultValue}")     private String property;      @Bean     public static PropertyPlaceholderConfigurer ppc() throws IOException {         PropertyPlaceholderConfigurer ppc = new PropertyPlaceholderConfigurer();         ppc.setLocations(new ClassPathResource("properties/" + property + ".properties"));         ppc.setIgnoreUnresolvablePlaceholders(true);         return ppc;     } } 

I run my application with following VM option:

-Dproperty=propertyValue 

So I'd like my application to load specific property file on startup. But for some reason at this stage @Value annotations are not processed and property is null. On the other hand if I have PropertyPlaceholderConfigurer configured via xml file - everything works perfectly as expected. Xml file example:

<bean class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">     <property name="ignoreResourceNotFound" value="true"/>     <property name="location">         <value>classpath:properties/${property:defaultValue}.properties</value>     </property> </bean> 

If I try to to inject property value in another Spring configuration file - it is properly injected. If I move my PropertyPlaceholderConfigurer bean creation to that configuration file - field value is null again.

As workaround, I use this line of code:

System.getProperties().getProperty("property", "defaultValue") 

Which is also works, but I'd like to know why such behavior is occurs and maybe it is possible to rewrite it in other way but without xml?

Answer 1

From Spring JavaDoc:

In order to resolve ${...} placeholders in definitions or @Value annotations using properties from a PropertySource, one must register a PropertySourcesPlaceholderConfigurer. This happens automatically when using context:property-placeholder in XML, but must be explicitly registered using a static @Bean method when using @Configuration classes. See the "Working with externalized values" section of @Configuration's javadoc and "a note on BeanFactoryPostProcessor-returning @Bean methods" of @Bean's javadoc for details and examples.

So, you are trying to use a placeholder in the code block required to enable placeholder processing.

As @M.Deinum mentioned, you should use a PropertySource (default or custom implementation).

Example below shows how to use properties in a PropertySource annotation as well as how to inject properties from the PropertySource in a field.

@Configuration @PropertySource(           value={"classpath:properties/${property:defaultValue}.properties"},           ignoreResourceNotFound = true) public class ConfigExample {      @Value("${propertyNameFromFile:defaultValue}")     String propertyToBeInjected;      /**      * Property placeholder configurer needed to process @Value annotations      */      @Bean      public static PropertySourcesPlaceholderConfigurer propertyConfigurer() {         return new PropertySourcesPlaceholderConfigurer();      } } 

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Update 09/2021

as Koray mentioned in the comment, the PropertySourcesPlaceholderConfigurer is not needed anymore since Spring 4.3+ / Spring Boot 1.5+. Dynamic filenames can be used for property files in @PropertySource and @ConfigurationProperties annotations without additional configuration.

@Configuration @PropertySource(           value={"classpath:properties/${property:defaultValue}.properties"},           ignoreResourceNotFound = true) public class ConfigExample {      @Value("${propertyNameFromFile:defaultValue}")     String propertyToBeInjected; } 

@ConfigurationProperties("properties/${property:defaultValue}.properties") public class ConfigExample {      String propertyNameFromFile; } 

Answer 2

For any other poor souls who couldn't get this to work in some Configuration classes when they work in others:

Look to see what other beans you have in that class and if any of them get instantiated early in the ApplicationContext. A ConversionService is an example of one. This would instantiate the Configuration class before what is required is registered, thereby making no property injection take place.

I fixed this by moving the ConversionService to another Configuration class that I Imported.