Access environment property using pure spring java configuration

Question

I am writing a web application using Spring with a pure Java configuration (no xml). I'd like a solution to expose various environment specific properties depending on where my application is running (dev/test/prod). Using Spring xml config and the PropertyPlaceholderConfigurer via xml, I would have done something like this:

<bean id="propertyConfigurer"
    class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
    <property name="systemPropertiesModeName" value="SYSTEM_PROPERTIES_MODE_OVERRIDE" />
    <property name="ignoreResourceNotFound" value="true" />
    <property name="locations">
        <list>
            <value>classpath:shift.properties</value>
            <value>classpath:shift-${env}.properties</value>
        </list>
    </property>
</bean>

In the Java configuration, the base of what I'm trying to do is the following:

@Configuration
@EnableWebMvc
@ComponentScan(basePackages = { "com.values.shift" })
public class WebConfig extends WebMvcConfigurerAdapter {

@Autowired
private static Environment springEnv;

@Bean
public static PropertyPlaceholderConfigurer propertyConfigurer() throws IOException {
    PropertyPlaceholderConfigurer props = new PropertyPlaceholderConfigurer();
    System.out.println("Environment:" + env.toString());
    props.setLocations(
            new Resource[] {
                    new ClassPathResource("shift.properties"), 
                    new ClassPathResource("shift-" + springEnv.getProperty("env") + ".properties")}
            );
    props.setIgnoreResourceNotFound(true);
    return props;
}

I have -Denv=localhost set as a VM argument on Tomcat. I also have it set as a system property on my mac (ie echo $env in the terminal outputs localhost)

I can't seem to figure out how to access that environment variable using pure Java. I have tried the following:

• Use Spring Environment as shown in the code above.
• @Value("#{ systemEnvironment['env'] }") for a new variable and access it as a string
• @Value("#{ systemProperties['env'] }") for a new variable and access it as a string
• @Value("${env}") for a new variable and access it as a string

All of the above return null. It would be great to see a working example of how to access environment variables using pure Java configuration in Spring.

Thanks for the help.

Answer 1

It tries to find 'env' property in properties file now.

You have missed to use systemPropertiesModeName method on PropertyPlaceholderConfigurer which will make your @Value("#{ systemProperties['env'] }") valid.

//edit:

dont use @Autowired on static fields.

//edit 2:

This is what im using:

@Configuration
public class PropertiesConfig {

@Bean
public PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
    return PropertyLoadHelper.getPropertySourcesPlaceholderConfigurer();
}

public static class PropertyLoadHelper {
    public static PropertySourcesPlaceholderConfigurer getPropertySourcesPlaceholderConfigurer() {
        PropertySourcesPlaceholderConfigurer properties = new PropertySourcesPlaceholderConfigurer();
        properties.setLocations(new ClassPathResource[]{
                new ClassPathResource("config/app." + System.getenv("ENV") + "properties"),
                new ClassPathResource("config/local.app." + System.getenv("ENV") + "properties"),
                new ClassPathResource("config/application.properties")
        });
        properties.setBeanName("app");
        properties.setLocalOverride(true);
        properties.setIgnoreResourceNotFound(true);
        return properties;
    }


    public static Properties loadProperties(String propertiesPath) {
        PropertiesFactoryBean propertiesFactoryBean = new PropertiesFactoryBean();
        propertiesFactoryBean.setLocation(new ClassPathResource(propertiesPath));
        Properties properties = null;
        try {
            propertiesFactoryBean.afterPropertiesSet();
            properties = propertiesFactoryBean.getObject();

        } catch (IOException e) {
            e.printStackTrace();
        }
        return properties;
    }

}

}

differences: PropertySourcesPlaceholderConfigurer used, System.getenv used instead Autowired Environment. Maybe Environment cant be used before setting PropertyPlaceHolder bean?