Spring Boot + Redis 实现延迟队列

在Spring Boot中，你可以使用@EnableScheduling注解来创建一个简单的延迟队列。以下是一个使用Redis作为延迟存储和调度的例子：

1. 添加依赖到你的pom.xml：

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-redis</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-web</artifactId>
</dependency>

2. 在Spring Boot应用的主类或配置类上添加@EnableScheduling注解：

@SpringBootApplication
@EnableScheduling
public class DelayQueueApplication {
    public static void main(String[] args) {
        SpringApplication.run(DelayQueueApplication.class, args);
    }
}

3. 创建一个延迟队列的任务：

@Component
public class DelayQueueTask {
 
    private static final Logger LOGGER = LoggerFactory.getLogger(DelayQueueTask.class);
 
    @Autowired
    private StringRedisTemplate stringRedisTemplate;
 
    @Scheduled(fixedRate = 5000)
    public void processDelayQueue() {
        List<String> keys = stringRedisTemplate.keys("delay_queue:*");
        for (String key : keys) {
            Long delay = stringRedisTemplate.getExpire(key, TimeUnit.SECONDS);
            if (delay != null && delay > 0) {
                // 任务还没有到期，继续等待
                continue;
            }
            // 获取任务并处理
            String task = stringRedisTemplate.opsForValue().get(key);
            if (task != null) {
                LOGGER.info("Processing task: {}", task);
                // 处理任务的逻辑
                // ...
                // 处理完毕后删除任务
                stringRedisTemplate.delete(key);
            }
        }
    }
 
    public void enqueueTask(String taskId, long delaySeconds) {
        stringRedisTemplate.opsForValue().set("delay_queue:" + taskId, "task_data",
                Duration.ofSeconds(delaySeconds));
    }
}

4. 使用enqueueTask方法向延迟队列中添加任务：

@RestController
public class DelayQueueController {
 
    @Autowired
    private DelayQueueTask delayQueueTask;
 
    @PostMapping("/enqueue")
    public String enqueueTask(@RequestParam String taskId, @RequestParam long delaySeconds) {
        delayQueueTask.enqueueTask(taskId, delaySeconds);