JAVA Spring Boot : How to access application.properties values in normal class

Question

I know how I can access the application.properties values in @Service classes in Java Spring boot like below

@Service
public class AmazonClient {

    @Value("${cloud.aws.endpointUrl}")
    private String endpointUrl;
}

But I am looking for an option to access this value directly in any class (a class without @Service annotation)

e.g.

public class AppUtils {
      @Value("${cloud.aws.endpointUrl}")
      private String endpointUrl;
}

But this returns null. Any help would be appreciated. I have already read here but didn't help.

maybe `@Autowired private Environment env;`? I know it's not the same, but... — Alberto Sinigaglia, Apr 15 '21 at 10:32
If the AppUtils class have strict dependency on the endpointUrl and there are more such properties, I would suggest you create a bean of properties and then pass it to the constructor of AppUtils through your component or service, because there spring will inject the bean for you. — code_mechanic, Apr 15 '21 at 10:39
Please refer this https://stackoverflow.com/questions/24649062/spring-read-property-value-from-properties-file-in-static-field-of-class/39368399 — Tushar Wasson, Apr 15 '21 at 10:40
https://stackoverflow.com/a/50940314/8874958 also helped a lot. Thank you @tusharwason — Kishan Solanki, Apr 15 '21 at 11:32

score 9 · Accepted Answer · answered Apr 15 '21 at 11:02

9

There's no "magic" way to inject values from a property file into a class that isn't a bean. You can define a static java.util.Properties field in the class, load values from the file manually when the class is loading and then work with this field:

public final class AppUtils {
    private static final Properties properties;

    static {
        properties = new Properties();

        try {
            ClassLoader classLoader = AppUtils.class.getClassLoader();
            InputStream applicationPropertiesStream = classLoader.getResourceAsStream("application.properties");
            applicationProperties.load(applicationPropertiesStream);
        } catch (Exception e) {
            // process the exception
        }
    }
}

answered Apr 15 '21 at 11:02

Igor Amelin

295
2
9

This worked. But everytime when any function called from AppUtils class, then I am accessing like this properties.getProperty("cloud.aws.endpointUrl") , I hope this doesn't lead to memory leak – Kishan Solanki Apr 15 '21 at 11:17
@KishanSolanki One follow up question, how would you create the `AppUtils` object in your code? – code_mechanic Apr 15 '21 at 11:36
1. This code doesn't lead to memory leak. The `static` block where we load properties from the file runs only once when this class is loaded by JVM. So if you start your application and use this class, the last one shouldn't be loaded again. – Igor Amelin Apr 15 '21 at 13:41
2. We can add static methods to get property from this `property` field, and then call this method in code: `var propertyValue = AppUtils.getSomePropertyValue()` – Igor Amelin Apr 15 '21 at 13:42
@IgorAmelin there seems to be an error in the code provided, shouldn't it be properties.load(applicationPropertiesStream); instead? Also are you able to update your answer and include the static method you made mention of above? – stebak Feb 23 '22 at 16:30
2

But using this approach will potentially introduce bugs if you use `application-.properties` where Spring intelligently reads properties that are overridden based on what profile is loaded. In this suggested utility, it will only ever look in the root `application.properties` file. – Steve Jan 05 '23 at 21:34

score 2 · Answer 2 · answered Apr 15 '21 at 10:50

You can easily achievw this by annotating ur app utils class with @component annotation . spring will take care of loading properties.

But if you don't want to do that approach , then look at the link below .

https://www.baeldung.com/inject-properties-value-non-spring-class

JAVA Spring Boot : How to access application.properties values in normal class

2 Answers2