Last week I was looking for a easy way to inject property values into my code. In my project I was using Camel in combination with Weld (CDI). One of the main requirements was that properties could be injected from multiple “locations”. From a property file or a system / environment property.

Because we are using Openshift to run our applications it is easy to use environment variables to inject your configuration. I did not want to write my own code to resolve the properties so I started looking. Eventually I found DeltaSpike, with DeltaSpike you can easily inject properties in your code and it works seamlessly with CDI.

You can inject properties from the following four locations:

  • System properties (ordinal = 400)
  • Environment properties (ordinal = 300)
  • JNDI values (ordinal = 200, the base name is “java:comp/env/deltaspike/”)
  • Properties file values (apache-deltaspike.properties) (ordinal = 100, default filename is “META-INF/apache-deltaspike.properties”)

When the same property is configured in two or more locations the value of the highest ordinal is used. So System properties will overwrite any configuration done in the property file.

Because I did not want to use the default property filename I implemented the following class in order to load my own property file:


import org.apache.deltaspike.core.api.config.PropertyFileConfig;

import javax.inject.Named;

@Named
public class MyCustomPropertyConfig implements PropertyFileConfig {

    @Override public String getPropertyFileName() {
      return "badasspropertyFile.properties";
    }

    @Override public boolean isOptional() {
      return true;
    }
}

There are three ways to load a property in your class.

  • ConfigResolver methods for easy programmatic access to values
  • TypedResolver API for typed configuration values and precise control over resolution
  • @ConfigProperty for injection of configured values into beans
  • interface based configuration

When using DeltaSpike in combination with CDI you can inject property values in a similar way you are used to when injecting beans. For this you can use the “@ConfigProperty” annotation:


@Inject
@ConfigProperty(name = "loglevel", defaultValue = "INFO")
  private String logLevel;

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