A simple rate limiter in Spring boot

Pom.xml

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>

    <groupId>com.manager.wealth</groupId>
    <artifactId>rate-limiter-demo</artifactId>
    <version>1.0-SNAPSHOT</version>

    <properties>
        <maven.compiler.source>22</maven.compiler.source>
        <maven.compiler.target>22</maven.compiler.target>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
    </properties>

    <dependencies>
        <!-- https://mvnrepository.com/artifact/org.springframework.boot/spring-boot-starter-web -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>3.4.2</version>
        </dependency>

        <!-- https://mvnrepository.com/artifact/com.bucket4j/bucket4j-core -->
        <dependency>
            <groupId>com.bucket4j</groupId>
            <artifactId>bucket4j-core</artifactId>
            <version>8.7.0</version>
        </dependency>
    </dependencies>


</project>

RateLimiterService

package com.ratelimiter.demo.services;

import io.github.bucket4j.Bandwidth;
import io.github.bucket4j.Bucket;
import org.springframework.stereotype.Service;

import java.time.Duration;
import java.util.concurrent.atomic.AtomicInteger;

@Service
public class RateLimiterService {

    private static final int CAPACITY = 5;  // Max number of requests allowed
    private static final Duration REFILL_DURATION = Duration.ofMinutes(1);  // Refill duration
    private static final int REFILL_AMOUNT = 5;  // Number of requests refilled every minute

    private final AtomicInteger requests = new AtomicInteger(0);  // Count for requests

    private final Bucket bucket;

    public RateLimiterService() {
        this.bucket = Bucket.builder()
                .addLimit(Bandwidth.simple(REFILL_AMOUNT, REFILL_DURATION))  // Limit configuration
                .build();
    }

    public boolean tryConsume() {
        return bucket.tryConsume(1);  // Tries to consume 1 token
    }

    public boolean isRateLimitExceeded() {
        return !tryConsume();
    }

    public int getRemainingTokens() {
        return (int) bucket.getAvailableTokens();
    }
}

RateLimitController

package com.ratelimiter.demo.rest;

import com.ratelimiter.demo.services.RateLimiterService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RestController;

@RestController
public class RateLimitController {

    @Autowired
    private RateLimiterService rateLimiterService;

    @GetMapping("/api/resource")
    public String accessResource() {
        if (rateLimiterService.isRateLimitExceeded()) {
            return "Rate limit exceeded. Try again later.";
        }
        return "Access granted to the resource!";
    }

    @GetMapping("/api/rateLimitStatus")
    public String rateLimitStatus() {
        return "Remaining requests: " + rateLimiterService.getRemainingTokens();
    }
}