Spring Condition not able to read value from property file

Question

I am trying to implement Spring Condition org.springframework.context.annotation.Condition as follows:

public class APIScanningDecisionMaker implements Condition {

   @Override
   public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {

    // Not able to read the property "swagger.scanner.can.run". It is always NULL.
    String canRunFlagInStr = context.getEnvironment().getProperty("swagger.scanner.can.run");
   // Ignore the rest of the code.
   }
}

However, as shown in the above code, when I read the property "swagger.scanner.can.run" it is always NULL. In my property file I have set it to "swagger.scanner.can.run=false".

I also tried to use the @Value("${swagger.scanner.can.run}") but even that returns NULL. When I put a debug in this method I can see that it is being called.

Just for the sake of completion I am using the APIScanningDecisionMaker as follows:

@Configuration
@EnableSwagger
@Conditional(APIScanningDecisionMaker.class)
public class CustomSwaggerConfig {
  // Ignore the rest of the code
}

Is there any reason why "swagger.scanner.can.run" is being retrieved as NULL?

Answer 1

Maybe spring doesn't know the file ?

This can be fix on annotated your class where the @Value("${swagger.scanner.can.run}") is used :

@PropertySource(value="classpath:config.properties")

Regards,

Answer 2

---

The object of class implementing "Condition" is created via constructor from Spring, so you can not inject values using @Value annotation. You can do something like below in your code:

@Override        
public boolean matches(
ConditionContext arg0, 
            AnnotatedTypeMetadata arg1) {       
        String prop = conditionContext.getEnvironment()
                 .getProperty("arg0");   
//further code   
     }    

Answer 3

If you add @Conditional to config class then APIScanningDecisionMaker should implement ConfigurationCondition . And don't forget to add @PropertySource to config class.

import org.springframework.context.annotation.ConfigurationCondition;

public class APIScanningDecisionMaker implement ConfigurationCondition {
    @Override
    public ConfigurationPhase getConfigurationPhase() {
        return ConfigurationPhase.REGISTER_BEAN;
    }
}

Properties will have been loaded in ConfigurationPhase.REGISTER_BEAN phase.

If you use @Conditional for methods then you could implement Condition .

Answer 4

You can manually load the properties file, if due to any problem its not loading into spring's context at the time it is constructing your Condition.

@Override
public boolean matches(ConditionContext context, AnnotatedTypeMetadata metadata) {
  try {
      Properties appProps = new Properties();
appProps.load(context.getResourceLoader().getResource("classpath:app.properties").getInputStream());
      String canRunFlagInStr = appProps.getProperty("swagger.scanner.can.run");
      return Boolean.parseBoolean(canRunFlagInStr);
  } catch (IOException e) {
      throw new ApplicationContextException(("Exception while loading context", e);
  }
}

Answer 5

this works fine for me

public boolean matches(ConditionContext conditionContext, AnnotatedTypeMetadata annotatedTypeMetadata) {
    try {
        InputStream i = conditionContext.getResourceLoader().getResource("prop.file").getInputStream();
        BufferedReader reader = new BufferedReader(new InputStreamReader(i));
        StringBuilder out = new StringBuilder();
        String line;
        while ((line = reader.readLine()) != null) {
            out.append(line);
        }
        System.out.println(out.toString());

    } catch (IOException e) {
        e.printStackTrace();
    }

    return true;
}