WildFly 11/Java EE 7/JSR 107：缓存 - 缓存信息并让它自动过期的最佳方法是什么？

Question

What's the recommended way to store pieces of data and let it expire automatically from within a Java EE/WebApp container? I could use the session persistence mechanism, but my http sessions are usually A LOT longer than I want those pieces of information to be retained.

Is there something provided by Java EE 7 or by CDI? Some preliminary variant of the JCache spec JSR 107? Any other good solution?

Answer 1

I'm not sure it is the "best" way but I've been using the Google Guava cache in Wildfly (8 through 10 but hopefully still applicable). For me I'm caching Oauth tokens because of a very slow auth server. My code looks something like:

private static LoadingCache<String, MyPrincipal> tokenCacheMap;

@PostConstruct
private void postConstruct() {
    tokenCacheMap = CacheBuilder.newBuilder()
            .expireAfterAccess(15, TimeUnit.MINUTES)
            .build(
                    new CacheLoader<String, MyUserPrincipal>() {
                        @Override
                        public MyUserPrincipal load(String token) {
                            MyUserPrincipal myUserPrincipal = getUserFromToken(token);

                            if( myUserPrincipal != null ) {
                                myUserPrincipal.setToken(token);
                                return myUserPrincipal;
                            }

                            throw new SecurityException("token is not valid");
                        }
                    }
            );
}

//
// later in the code...
//
MyUserPrincipal myUserPrincipal = tokenCacheMap.get(token);

Basically what this does is set up a cache where the tokens live for 15 minutes. If needed, the load() method is called to, in this case, get an auth token and user. The cache is lazily filled as needed - the first call will have the overhead of getting the token but after that it's all in memory.

There are other options to, for example, evict old information based on the number of items in the cache. The documentation is very good and should get you going.

The downside is that this is not a JEE standard but it has worked for me in the past.

Answer 2

You can use infinispan-jcache if you want to use the JCache API. Infinispan is a scalable, highly available key/value data store included in WildFly .

To use it , add infinispan-jcache to pom.xml :

<dependency>
    <groupId>org.infinispan</groupId>
    <artifactId>infinispan-jcache</artifactId>
    <version>...</version> <!-- e.g. 9.1.4.Final -->
</dependency>

and access the cache as follows :

import javax.cache.Cache;
import javax.cache.CacheManager;
import javax.cache.Caching;
import javax.cache.configuration.CompleteConfiguration;
import javax.cache.configuration.MutableConfiguration;
import javax.cache.expiry.CreatedExpiryPolicy;
import javax.cache.expiry.Duration;
import javax.cache.spi.CachingProvider;
import java.util.concurrent.TimeUnit;

...

// Construct a simple local cache manager with default configuration
// and default expiry time of 5 minutes.
CacheManager cacheManager = Caching.getCachingProvider().getCacheManager();
CompleteConfiguration<String, String> configuration = new 
MutableConfiguration<String, String>()
            .setTypes(String.class, String.class)
            .setExpiryPolicyFactory(factoryOf(new CreatedExpiryPolicy(
                    new Duration(TimeUnit.MINUTES, 5))));

// Create a cache using the supplied configuration.
Cache<String, String> cache = cacheManager.createCache("myCache", configuration);

// Store a value, the entry will expire in 2 seconds.
cache.put("key", "value", 2, TimeUnit.SECONDS);
// Retrieve the value and print it out.
System.out.printf("key = %s\n", cache.get("key"));

// Stop the cache manager and release all resources,
// use try-with-resources in real code.
cacheManager.close();

Note that Infinispan has great docs .