一个简单的java缓存实现

一个简单的java缓存实现

import java.util.Map;
import java.util.WeakHashMap;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

public final class SimpleCache<K, V> {

private final Lock lock = new ReentrantLock();
private final int maxCapacity;
private final Map<K, V> eden;
private final Map<K, V> perm;

public SimpleCache(int maxCapacity) {
this.maxCapacity = maxCapacity;
this.eden = new ConcurrentHashMap<K, V>(maxCapacity);
this.perm = new WeakHashMap<K, V>(maxCapacity);
}

public V get(K k) {
V v = this.eden.get(k);
if (v == null) {
lock.lock();
try {
v = this.perm.get(k);
} finally {
lock.unlock();
}
if (v != null) {
this.eden.put(k, v);
}
}
return v;
}

public void put(K k, V v) {
if (this.eden.size() >= maxCapacity) {
lock.lock();
try {
this.perm.putAll(this.eden);
} finally {
lock.unlock();
}
this.eden.clear();
}
this.eden.put(k, v);
}
}