use of @Value Spring annotation during Controller initialization issue

Question

Probably someone else might have asked something similar as well, but I couldn't find an answer that provides a solution that works... I'm in the process of learning spring boot and while I was playing with guava RateLimiter during my experiments I hit the following problem: RateLimiter needs to be created during the Controller initialization, but if I want to load the rate I have to hardcode it, since if I try to load it from props using attributes with @Value Spring annotations it doesn't work. Is there any "trick" around this "limitation"? see code below:

@RestController
public class LoggingController {
    private Logger logger = LoggerFactory.getLogger(LoggingController.class);

    @Value("${count}")
    private Double PERMITS_COUNT;
    @Value("${seconds}")
    private Double PERMITS_PER_SECONDS;
    @Value("${consumed}")
    private int PERMITS_CONSUMED;

//@ Value fails here with NullPointerException
    private RateLimiter rateLimiter = RateLimiter.create(PERMITS_COUNT / PERMITS_PER_SECONDS);
// This works file
private RateLimiter rateLimiter = RateLimiter.create(10d / 60d);

    private AtomicInteger index = new AtomicInteger(0);


    @GetMapping("/logging")
    @ResponseBody
    public String logging (@RequestParam(name="name", required=false, defaultValue="JavaBoss") String name) {

//@Value works fine if used here
        rateLimiter.setRate(PERMITS_COUNT / PERMITS_PER_SECONDS);
        rateLimiter.acquire(PERMITS_CONSUMED);
...

Many thanks in advance...

Answer 1

Use PostConstruct and you should be fine

 @RestController
    public class LoggingController {
        private Logger logger = LoggerFactory.getLogger(LoggingController.class);
    
        @Value("${count}")
        private Double PERMITS_COUNT;
        @Value("${seconds}")
        private Double PERMITS_PER_SECONDS;
        @Value("${consumed}")
        private int PERMITS_CONSUMED;
        
        private RateLimiter rateLimiter;
        
        @PostConstruct 
        private void createRateLimiter() {
         rateLimiter = RateLimiter.create(PERMITS_COUNT / PERMITS_PER_SECONDS);
        }
        
    
        private AtomicInteger index = new AtomicInteger(0);
    
    
        @GetMapping("/logging")
        @ResponseBody
        public String logging (@RequestParam(name="name", required=false, defaultValue="JavaBoss") String name) {
    
    
    ...