We want to create a simple service that returns five random numbers. An example response from the service is shown here:

 [5,6,6,4,992]

It should be easy to build a RESTful controller to return a list of five random numbers. The following snippet shows the implementation details:

@RestController
public class RandomNumberController {

      private Log log =
        LogFactory.getLog(RandomNumberController.class);

      @RequestMapping("/random")
      public List<Integer> random() {

        List<Integer> numbers = new ArrayList< >();

        for (int i = 1; i <= 5; i++) {
          numbers.add(generateRandomNumber());
        }

        log.info("Returning " + numbers);

        return numbers;

      }

      private int generateRandomNumber() {
        return (int) (Math.random() * 1000);
      }
}

Some important things to note are as follows:

• @RequestMapping("/random") public List<Integer> random(): This is a random service that returns a list of random numbers.
• private int generateRandomNumber() {: This generates random numbers between 0 and 1000.

The following snippet shows a sample response from the service at http://localhost:8080/random:

[666,257,306,204,992]