Cross-origin resource sharing (CORS) from Spring Boot Rest Controllers

Was involved in a hackathon recently and after creating a few Spring boot API's for the UI team to consume and they run into errors around (Cross-origin resource sharing ). For security reasons, browsers prohibit AJAX calls to resources residing outside the current origin.

I have seen this before and Spring Boot has support to ensure you can control which resources can be accessed outside of the current origin. It's as simple as an annotation "@CrossOrigin", as shown below. In this example every request from this Rest Controller supports resource calls residing outside the current origin.

  
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.http.HttpStatus;
import org.springframework.http.MediaType;
import org.springframework.web.bind.annotation.*;

import java.util.List;

@CrossOrigin
@RestController
@RequestMapping(value = "/beacon")
public class BeaconRest
{
    private static Log logger = LogFactory.getLog(BeaconRest.class);

    @Autowired
    private BeaconRepository beaconRepository;

    @RequestMapping(value = "/all",
            method = RequestMethod.GET,
            produces = MediaType.APPLICATION_JSON_VALUE)
    public List<Beacon> allBeacons()
    {
        logger.info("Invoking /beacon/all RESTful method");
        return beaconRepository.findAll();
    }

Of course it's much more flexible then that adding the ability to add options, and you can read more about it here.

https://docs.spring.io/spring/docs/4.2.x/spring-framework-reference/html/cors.html