How to get the value from system property in spring boot

Question

I am using following command to run my spring boot application

java -Dlibrary.system.property=value -jar myapp.jar

Currently, I am able to access it via following command like below

System.getProperty("library.system.property")

However I need to access it via any annotation in Spring something like

@value(${library.system.property})

I tried to use

    @Value("${library.system.property")
    private String property;

    @Bean
    public SampleProvider getSampleProvider () {
        return SampleProvider.from(property);
    }

But the value of the property is null. Do I need to use conditional bean or something?

Answer 1

You can access the system properties using the following expression:

@Value("#{systemProperties['library.system.property']}")
private String property

You can also access the system environment using the following expression:

@Value("#{systemEnvironment['SOME_ENV_VARIABLE']}")
private String property

Lastly, if you are using Spring Boot you can refer to the property name directly as long as you are passing it in the command line. For example, if you launch the JAR like java -jar boot.jar --some.property=value you can read it as:

@Value("${some.property}")
private String property