ListenerObject not found in imports for Ehcache 3? - ehcache

Question

I am trying to implement a listener for an Ehcache 3.3.1 project using the code below. Can anyone suggest a solution for the ListenerObject? I can't seem to find it anywhere,except on the docs page I got the code from
import java.util.logging.Level;
import java.util.logging.Logger;
import org.ehcache.Cache;
import org.ehcache.CacheManager;
import org.ehcache.config.builders.CacheConfigurationBuilder;
import org.ehcache.config.builders.CacheEventListenerConfigurationBuilder;
import org.ehcache.config.builders.CacheManagerBuilder;
import org.ehcache.config.builders.ResourcePoolsBuilder;
import org.ehcache.event.EventType;
public class CacheHandler{
private Logger LOG = Logger.getLogger(this.getClass().getName());
private String cacheName="basicCache";
public Cache cache;
public CacheHandler(){
if(cache==null)
cache=initCache();
}
private Cache initCache(){
CacheEventListenerConfigurationBuilder cacheEventListenerConfiguration = CacheEventListenerConfigurationBuilder
.newEventListenerConfiguration(new ListenerObject(), EventType.CREATED, EventType.UPDATED)
.unordered().asynchronous();
final CacheManager manager = CacheManagerBuilder.newCacheManagerBuilder()
.withCache(cacheName,
CacheConfigurationBuilder.newCacheConfigurationBuilder(String.class, String.class, ResourcePoolsBuilder.heap(10))
.add(cacheEventListenerConfiguration)
).build(true);
final Cache<String, String> cache = manager.getCache("foo", String.class, String.class);
return cache;
}
public Cache getCache(){
if(cache==null)
cache=initCache();
return cache;
}
}

Answer 1

It is indeed not mentioned but since it is only one method it is normally easy to figure out.
Here is an example:
public class ListenerObject implements CacheEventListener<Object, Object> {
#Override
public void onEvent(CacheEvent<? extends Object, ? extends Object> event) {
System.out.println(event);
}
}
The real one used in the documentation is here.
Then, I've played a bit with your code to real production usable code.
public class CacheHandler implements AutoCloseable {
private static final String CACHE_NAME = "basicCache";
private final Cache<String, String> cache;
private final CacheManager cacheManager;
public CacheHandler() {
cacheManager = initCacheManager();
cache = cacheManager.getCache(CACHE_NAME, String.class, String.class);
}
private CacheManager initCacheManager(){
CacheEventListenerConfigurationBuilder cacheEventListenerConfiguration = CacheEventListenerConfigurationBuilder
.newEventListenerConfiguration(new ListenerObject(), EventType.CREATED, EventType.UPDATED)
.ordered().synchronous();
return CacheManagerBuilder.newCacheManagerBuilder()
.withCache(CACHE_NAME,
CacheConfigurationBuilder.newCacheConfigurationBuilder(String.class, String.class, ResourcePoolsBuilder.heap(10))
.add(cacheEventListenerConfiguration)
).build(true);
}
public Cache getCache(){
return cache;
}
#Override
public void close() {
cacheManager.close();
}
public static void main(String[] args) {
try(CacheHandler handler = new CacheHandler()) {
Cache<String, String> cache = handler.getCache();
cache.put("a", "b");
cache.putIfAbsent("a", "c");
}
}
}
Some comments:
I assumed you want singleton cache kept in a variable. So that's what I did. The lazy initCache wasn't useful because the withCache tells Ehcache to create the cache when creating the cache manager.
We will want to keep a reference to the CacheManager in order to close it at the end.
The getCache was retrieving "foo", not "basicCache"