Chapter 4. Injecting configuration values into your Quarkus application

Procedure

1. Review the GreetingResource.java file and make sure it includes the following import statements:

   src/main/java/org/acme/config/GreetingResource.java

   import java.util.Optional;
   import javax.inject.Inject;

2. Create a file GreetingConfiguration.java in the src/main/java/org/acme/config directory.

3. Add the ConfigProperties and Optional imports to the GreetingConfiguration.java file:

   src/main/java/org/acme/config/GreetingConfiguration.java

   import io.quarkus.arc.config.ConfigProperties;
   import java.util.Optional;
   import javax.inject.Inject;

4. Create a GreetingConfiguration class for the greeting properties in your GreetingConfiguration.java file:

   src/main/java/org/acme/config/GreetingConfiguration.java

   @ConfigProperties(prefix = "greeting") 

   1

   
   public class GreetingConfiguration {
   
       private String message;
       private String suffix = "!"; 

   2

   
       private Optional<String> name;
   
       public String getMessage() {
           return message;
       }
   
       public void setMessage(String message) {
           this.message = message;
       }
   
       public String getSuffix() {
           return suffix;
       }
   
       public void setSuffix(String suffix) {
           this.suffix = suffix;
       }
   
       public Optional<String> getName() {
           return name;
       }
   
       public void setName(Optional<String> name) {
           this.name = name;
       }
   }

   1

   prefix is optional. If you do not specify a prefix, it is determined by the name of the class. In this example, the prefix is greeting.

   2

   If greeting.suffix is not set, ! is the default value.

5. Inject the GreetingConfiguration class into the GreetingResource class using the @Inject annotation:

   src/main/java/org/acme/config/GreetingResource.java

   @Path("/greeting")
   public class GreetingResource {
   
       @Inject
       GreetingConfiguration config;
   
       @GET
       @Produces(MediaType.TEXT_PLAIN)
       public String hello() {
           return config.getMessage() + " " + config.getName().orElse("world") + config.getSuffix();
       }
   }

6. Compile and start your application in development mode:

   ./mvnw quarkus:dev

   Important

   If you do not provide values for the class properties, the application fails to compile and you receive a javax.enterprise.inject.spi.DeploymentException that indicates a missing value. This does not apply to Optional fields and fields with a default value.

7. Enter the following command in a new terminal window to verify that the endpoint returns the message:

   curl http://localhost:8080/greeting

8. You receive the following message:

   hello quarkus!

9. Press CTRL+C to stop the application.

Procedure

1. Review the GreetingConfiguration.java file and make sure it includes the following import statements:

   src/main/java/org/acme/config/GreetingConfiguration.java

   import io.quarkus.arc.config.ConfigProperties;
   import java.util.Optional;
   import java.util.List;

2. Add the configuration in your GreetingConfiguration.java file using the @ConfigProperties annotation.

   The following example shows the configuration of the GreetingConfiguration class and its properties:

   src/main/java/org/acme/config/GreetingConfiguration.java

   @ConfigProperties(prefix = "greeting")
   public class GreetingConfiguration {
   
       public String message;
       public String suffix = "!";
       public Optional<String> name;
   }

3. Add a nested class inside the GreetingConfiguration class as shown in the following example:

   src/main/java/org/acme/config/GreetingConfiguration.java

   @ConfigProperties(prefix = "greeting")
   public class GreetingConfiguration {
   
       public String message;
       public String suffix = "!";
       public Optional<String> name;
       public ContentConfig content;
   
       public static class ContentConfig {
           public Integer prizeAmount;
           public List<String> recipients;
       }
   }

   This example shows a nested class ContentConfig. The name of the field, in this case content, determines the name of the properties bound to the object.

4. Set the greeting.content.prize-amount and greeting.content.recipients configuration properties in your application.properties file.

   The following example shows the values of properties for the GreetingConfiguration and ContentConfig classes:

   src/main/resources/application.properties

   greeting.message = hello
   greeting.name = quarkus
   greeting.content.prize-amount=10
   greeting.content.recipients=Jane,John

5. Inject the GreetingConfiguration class into the GreetingResource class using the @Inject annotation, and update the message string that the /greeting endpoint returns to have the message show the values that you set for the new greeting.content.prize-amount and greeting.content.recipients properties that you added:

   src/main/java/org/acme/config/GreetingResource.java

   @Path("/greeting")
   public class GreetingResource {
   
       @Inject
       GreetingConfiguration config;
   
       @GET
       @Produces(MediaType.TEXT_PLAIN)
       public String hello() {
           return config.message + " " + config.name.orElse("world") + config.suffix + "\n" + config.content.recipients + " receive total of candies: " + config.content.prizeAmount;
       }
   }

6. Compile and start your application in development mode:

   ./mvnw quarkus:dev

   Important

   If you do not provide values for the class properties, the application fails to compile and you receive a javax.enterprise.inject.spi.DeploymentException that indicates a missing value. This does not apply to Optional fields and fields with a default value.

7. Enter the following command in a new terminal window to verify that the endpoint returns the message:

   curl http://localhost:8080/greeting

8. You receive the message that contains the greeting on the first line and the recipients of the prize and the prize amount on the second line:

   hello quarkus!
   Jane,John receive total of candies: 10

9. Press CTRL+C to stop the application.

Procedure

1. Review the GreetingConfiguration.java file and make sure it includes the following import statements:

   src/main/java/org/acme/config/GreetingConfiguration.java

   import io.quarkus.arc.config.ConfigProperties;
   import org.eclipse.microprofile.config.inject.ConfigProperty;
   import java.util.Optional;

2. Add a GreetingConfiguration class as an interface to your GreetingConfiguration.java file:

   src/main/java/org/acme/config/GreetingConfiguration.java

   @ConfigProperties(prefix = "greeting")
   public interface GreetingConfiguration {
   
       @ConfigProperty(name = "message") 

   1

   
       String message();
   
       @ConfigProperty(defaultValue = "!")
       String getSuffix(); 

   2

   
   
       Optional<String> getName(); 

   3

   
   }

   1

   You must set the @ConfigProperty annotation because the name of the configuration property does not follow the getter method naming conventions.

   2

   In this example, name was not set so the corresponding property will be greeting.suffix.

   3

   You do not need to specify the @ConfigProperty annotation because the method name follows the getter method naming conventions (greeting.name being the corresponding property) and no default value is needed.

3. Inject the GreetingConfiguration class into the GreetingResource class using the @Inject annotation:

   src/main/java/org/acme/config/GreetingResource.java

   @Path("/greeting")
   public class GreetingResource {
   
       @Inject
       GreetingConfiguration config;
   
       @GET
       @Produces(MediaType.TEXT_PLAIN)
       public String hello() {
           return config.message() + " " + config.getName().orElse("world") + config.getSuffix();
       }
   }

4. Compile and start your application in development mode:

   ./mvnw quarkus:dev

   Important

   If you do not provide values for the class properties, the application fails to compile and you receive a javax.enterprise.inject.spi.DeploymentException that indicates a missing value. This does not apply to Optional fields and fields with a default value.

5. Enter the following command in a new terminal window to verify that the endpoint returns the message:

   curl http://localhost:8080/greeting

6. You receive the following message:

   hello quarkus!

7. Press CTRL+C to stop the application.