Spring Property Injection in a final attribute @Value - Java

Question

A simple question on Spring injection from a properties file for a final attribute.

I have a properties file which I want to store a file path in. Generally when I use properties files I setup class attributes using something like this:

private @Value("#{someProps['prop.field']}") String someAttrib ;

Then in my spring.xml I would have something like:

<util:properties id="someProps"   
    location="classpath:/META-INF/properties/somePropFile.properties" />

This works well, is simple and makes code nice and neat. But I'm not sure what is the neatest pattern to use when trying to inject properties values into final class attributes?

Obviously something like:

private static final @Value("#{fileProps['dict.english']}") String DICT_PATH; 

will not work. Is there another way?

Cheers!

Answer 1

The only way you can inject values into a final field is through Constructor Injection. Everything else would be an awful hack on Spring's side.

Answer 2

If you are looking for an example here is one:

public class Test {
    private final String value;

    public Test(@Value("${some.value}") String value){
        this.value=value;
        System.out.println(this.value);
    }
}