yathirigan yathirigan - 7 months ago 1025
Java Question

How to inject a Map using the @Value Spring Annotation?

How can i inject values into a Map from the properties file using the @Value annotation in Spring ?

My Spring Java class is and i tried using the $ but, got the following error message


Could not autowire field: private java.util.Map Test.standard; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'com.test.standard' in string value "${com.test.standard}"


@ConfigurationProperty("com.hello.foo")
public class Test {

@Value("${com.test.standard}")
private Map<String,Pattern> standard = new LinkedHashMap<String,Pattern>

private String enabled;

}


I have the following properties in a .properties file

com.test.standard.name1=Pattern1
com.test.standard.name2=Pattern2
com.test.standard.name3=Pattern3
com.hello.foo.enabled=true

Answer

I believe Spring Boot supports loading properties maps out of the box with @ConfigurationProperties annotation.

According that docs you can load properties:

my.servers[0]=dev.bar.com
my.servers[1]=foo.bar.com

into bean like this:

@ConfigurationProperties(prefix="my")
public class Config {

    private List<String> servers = new ArrayList<String>();

    public List<String> getServers() {
        return this.servers;
    }
}

I used @ConfigurationProperties feature before, but without loading into map. You need to use @EnableConfigurationProperties annotation to enable this feature.

Cool stuff about this feature is that you can validate your properties.