How to autowire @ConfigurationProperties into @Con

问题:

I have a properties class defined like this:

@Validated
@ConfigurationProperties(prefix = "plugin.httpclient")
public class HttpClientProperties {
   ...
}

And a configuration class like this:

@Configuration
@EnableScheduling
public class HttpClientConfiguration {

    private final HttpClientProperties httpClientProperties;

    @Autowired
    public HttpClientConfiguration(HttpClientProperties httpClientProperties) {
        this.httpClientProperties = httpClientProperties;
    }

    ...
}

When starting my spring boot application, I'm getting

Parameter 0 of constructor in x.y.z.config.HttpClientConfiguration required a bean of type 'x.y.z.config.HttpClientProperties' that could not be found.

Is this not a valid use case, or do I have to declare the dependencies some how?

回答1:

This is a valid use case, however, your HttpClientProperties are not picked up because they're not scanned by the component scanner. You could annotate your HttpClientProperties with @Component:

@Validated
@Component
@ConfigurationProperties(prefix = "plugin.httpclient")
public class HttpClientProperties {
    // ...
}

Another way of doing so (as mentioned by Stephane Nicoll) is by using the @EnableConfigurationProperties() annotation on a Spring configuration class, for example:

@EnableConfigurationProperties(HttpClientProperties.class) // This is the recommended way
@EnableScheduling
public class HttpClientConfiguration {
    // ...
}

This is also described in the Spring boot docs.