Spring-Boot multi module project load property-file

Question

I have a Spring-Boot-Application as a multimodule-Project in maven. The structure is as follows:

Parent-Project
|--MainApplication
|--Module1
|--ModuleN

In the MainApplication project there is the main() method class annotated with @SpringBootApplication and so on. This project has, as always, an application.properties file which is loaded automatically. So I can access the values with the @Value annotation

@Value("${myapp.api-key}")
private String apiKey;

Within my Module1 I want to use a properties file as well (called module1.properties), where the modules configuration is stored. This File will only be accessed and used in the module. But I cannot get it loaded. I tried it with @Configuration and @PropertySource but no luck.

@Configuration
@PropertySource(value = "classpath:module1.properties")
public class ConfigClass {

How can I load a properties file with Spring-Boot and access the values easily? Could not find a valid solution.

My Configuration

@Configuration
@PropertySource(value = "classpath:tmdb.properties")
public class TMDbConfig {

    @Value("${moviedb.tmdb.api-key}")
    private String apiKey;

    public String getApiKey() {
        return apiKey;
    }

    @Bean
    public static PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() {
        return new PropertySourcesPlaceholderConfigurer();
    }
}

Calling the Config

@Component
public class TMDbWarper {

@Autowired
private TMDbConfig tmdbConfig;

private TmdbApi tmdbApi;

public TMDbWarper(){
    tmdbApi = new TmdbApi(tmdbConfig.getApiKey());
}

I'm getting an NullPointerException in the constructor when I autowire the warper.

Answer 1

For field injection:

Fields are injected right after construction of a bean, before any config methods are invoked. Such a config field does not have to be public. Refer Autowired annotation for complete usage. Use constructor injection in this case like below:

@Component
public class TMDbWarper {

    private TMDbConfig tmdbConfig;

    private TmdbApi tmdbApi;

    @Autowired
    public TMDbWarper(final TMDbConfig tmdbConfig){
            this.tmdbConfig = tmdbConfig;
            tmdbApi = new TmdbApi(tmdbConfig.getApiKey());
    }

(or)

Use @PostConstruct to initialise like below:

@Component
public class TMDbWarper {

    @Autowired
    private TMDbConfig tmdbConfig;

    private TmdbApi tmdbApi;

    @PostConstruct
    public void init() {
        // any initialisation method
        tmdbConfig.getConfig();
    }