更新（首次发布后约4年…）：请注意，在较新版本的ehcache中，缓存项的持久性仅在付费产品中可用。感谢@boday指出这一点。
ehcache很棒。它将为您提供在内存，磁盘或具有溢出到磁盘的内存中实现映射所需的灵活性。如果为java.util.Map使用这个非常简单的包装器，那么使用它就非常简单：
import java.util.Collection;
import java.util.List;
import java.util.Map;
import java.util.Set;
import net.sf.ehcache.Cache;
import net.sf.ehcache.Element;
import org.apache.log4j.Logger;
import com.google.common.collect.Sets;
public class EhCacheMapAdapter<K,V> implements Map<K,V> {
@SuppressWarnings("unused")
private final static Logger logger = Logger
.getLogger(EhCacheMapAdapter.class);
public Cache ehCache;
public EhCacheMapAdapter(Cache ehCache) {
super();
this.ehCache = ehCache;
} // end constructor
@Override
public void clear() {
ehCache.removeAll();
} // end method
@Override
public boolean containsKey(Object key) {
return ehCache.isKeyInCache(key);
} // end method
@Override
public boolean containsValue(Object value) {
return ehCache.isValueInCache(value);
} // end method
@Override
public Set<Entry<K, V>> entrySet() {
throw new UnsupportedOperationException();
} // end method
@SuppressWarnings("unchecked")
@Override
public V get(Object key) {
if( key == null ) return null;
Element element = ehCache.get(key);
if( element == null ) return null;
return (V)element.getObjectValue();
} // end method
@Override
public boolean isEmpty() {
return ehCache.getSize() == 0;
} // end method
@SuppressWarnings("unchecked")
@Override
public Set<K> keySet() {
List<K> l = ehCache.getKeys();
return Sets.newHashSet(l);
} // end method
@SuppressWarnings("unchecked")
@Override
public V put(K key, V value) {
Object o = this.get(key);
if( o != null ) return (V)o;
Element e = new Element(key,value);
ehCache.put(e);
return null;
} // end method
@Override
public V remove(Object key) {
V retObj = null;
if( this.containsKey(key) ) {
retObj = this.get(key);
} // end if
ehCache.remove(key);
return retObj;
} // end method
@Override
public int size() {
return ehCache.getSize();
} // end method
@Override
public Collection<V> values() {
throw new UnsupportedOperationException();
} // end method
@Override
public void putAll(Map<? extends K, ? extends V> m) {
for( K key : m.keySet() ) {
this.put(key, m.get(key));
} // end for
} // end method
} // end class
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