Redisson 使用示例

Redisson 是一个 Java 的 Redis 客户端，基于 Redis 实现了许多分布式数据结构和功能，例如分布式锁、缓存、限流器、布隆过滤器等。

以下是一些常见的 Redisson 使用示例，来自ChatGPT，用于自学。

Redisson 提供了 RLock 接口用于实现分布式锁，适用于需要同步访问共享资源的分布式应用场景。

Redisson 提供了 RMap，可以在 Redis 中存储键值对，类似于 Java 的 Map，但支持分布式。

Redisson 支持布隆过滤器（RBloomFilter），可用于检测一个元素是否在集合中。

它适用于需要快速判断某元素是否存在于某集合的场景。

Redisson 提供了 RRateLimiter 接口，可用于实现限流功能，控制某一资源的访问速率。

Redisson 也支持发布/订阅模式的分布式消息队列，可以用于事件驱动的应用程序。

Redisson 提供的 RMapCache 支持自动过期和最大容量控制，可用于分布式缓存。

public static void main(String[] args) {
    // Create a Config instance and configure Redis connection
    Config config = new Config();
    config.useSingleServer().setAddress("redis://" + REDIS_HOST + ":" + REDIS_PORT).setPassword(redisPassword);
    // Create a RedissonClient instance
    RedissonClient redissonClient = Redisson.create(config);

    // use redissonClient to perform Redis operations
    // Example1: get a distributed lock
    RLock lock = redissonClient.getLock("myLock");
    try {
        // Attempt to add a lock and set the automatic expiration time of the lock to 10 seconds
        if (lock.tryLock()) {
            System.out.println("Successfully get lock, execute business logic");
            Thread.sleep(5000); // Simulate task execution
        } else {
            System.out.println("Can not get lock, execute other logic");
        }
    } catch (InterruptedException e) {
        e.printStackTrace();
    } finally {
        // release lock
        lock.unlock();
    }

    // Example2: get RMap object
    RMap<String, String> map = redissonClient.getMap("myMap");
    //put data into the map
    map.put("name", "Alice");
    map.put("city", "New York");
    System.out.println("Name: " + map.get("name"));
    System.out.println("City: " + map.get("city"));

    // Example3: get RBloomFilter object
    RBloomFilter<String> bloomFilter = redissonClient.getBloomFilter("myBloomFilter");
    // initialize BloomFilter, set the expected number of elements to 10000 and the false positive probability to 0.01
    bloomFilter.tryInit(10000, 0.01);
    // add elements to BloomFilter
    bloomFilter.add("Alice");
    bloomFilter.add("Bob");
    // check if elements exist in BloomFilter
    System.out.println("Alice exist: " + bloomFilter.contains("Alice"));
    System.out.println("Eve exist: " + bloomFilter.contains("Eve"));

    // Example4:get RateLimiter object
    RRateLimiter rateLimiter = redissonClient.getRateLimiter("myRateLimiter");
    // set the rate limit to 5 permits per second
    rateLimiter.trySetRate(RateType.OVERALL, 5, 1, RateIntervalUnit.SECONDS);
    for (int i = 0; i < 10; i++) {
        // try to acquire a permit
        if (rateLimiter.tryAcquire()) {
            System.out.println("the " + i + " operation  is allowed");
        } else {
            System.out.println("the " + i + " operation was limited in current");
        }
    }

    // Example5: get Topic object
    RTopic topic = redissonClient.getTopic("myTopic");
    // subscribe to a message
    topic.addListener(String.class, new MessageListener<String>() {
        @Override
        public void onMessage(CharSequence channel, String message) {
            System.out.println("Received message:" + message);
        }
    });
    // publish message to the topic
    topic.publish("Hello, Redis!");

    // Example6: get RMapCache object
    RMapCache<String, String> cache = redissonClient.getMapCache("myCache");
    // put data into the cache
    cache.put("key1", "value1", 10, TimeUnit.SECONDS);  // Expires in 10 seconds
    System.out.println("Key1: " + cache.get("key1"));
    // Delay access for a few seconds and verify expiration time
    try {
        Thread.sleep(11000);  // Delay 11s
    } catch (InterruptedException e) {
        Thread.currentThread().interrupt();
    }
    System.out.println("Key1 after 11 seconds: " + cache.get("key1"));  // out put null(Expired)

    // close RedissonClient
    redissonClient.shutdown();
}

> Task :RedissonExample.main()

Successfully get lock, execute business logic
Name: Alice
City: New York
Alice exist: true
Eve exist: false
the 0 operation is allowed
the 1 operation is allowed
the 2 operation is allowed
the 3 operation is allowed
the 4 operation is allowed
the 5 operation is allowed
the 6 operation is allowed
the 7 operation is allowed
the 8 operation is allowed
the 9 operation is allowed
Received message:Hello, Redis!
Key1: value1
Key1 after 11 seconds: null