如何通过 Spring 启动 Spring 数据从 redis 缓存中获取所有密钥？

Question

I am trying to get the entries in a Spring Boot Cache backed by Redis How do I get all the keys from a redis cache via Spring Boot? uses 1.x of Spring-Data-Redis and the current version uses DefaultRedisCacheWriter for the native cache.

Answer 1

I did this several years ago with spring boot 2 (so not sure if this'll work for you with v1), but what I remember is that the Redis cache is actually built upon a number of caches, each having a name. This is typically setup in a @Configuration class. Each cache is then just a map of key-value pairs, which is what the application would supply.

This is just an example for this use-case (where the developer fully controls the caching), as I wasn't really interested in the Spring-annotated methods for caching method responses.

In my configuration class, I create a CacheManager object which is configured with the various caches I intend to use within my application, and those would include the names and their TTL values supplied in a hashmap.

Here's some code (untested, so you may need to tweak it):

@Autowired
private CacheManager cacheManager;

@Autowired
private RedisTemplate redisTemplate;


public String getValue(String cacheName, String key) {
  cacheManager.getCache(cacheName).get(key);
}

public Map<String, String> getCache(String cacheName) {
    return redisTemplate
      .keys(cacheName+"*")
      .parallelStream()
      .map(key -> {
          Map<String, String> cacheEntries = new HashMap<>();
          cacheEntries.put(key, getValue(cacheName, key));
          return cacheEntries;
        }
      )
      .collect(Collectors.toList());
}

public void getAllCaches() {
  cacheManager.getCacheNames().forEach(cacheName -> {
    Map<String, String> cacheObject = getCache(cacheName);
    cacheObject.entrySet().stream().peek(entry -> {
      System.out.println(entry.getKey() + " = " + entry.getValue());
    });
  }
}