(转)超简单的缓存实现
基于ConcurrentHashMap和WeakHashMap的简单缓存实现 package test; 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> longterm; public SimpleCache(int maxCapacity) { this.maxCapacity = maxCapacity; this.eden = new ConcurrentHashMap<K,V>(maxCapacity); this.longterm = new WeakHashMap<K,V>(maxCapacity); } public V get(K k) { V v = this.eden.get(k); if (v == null) { lock.lock(); try{ v = this.longterm.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.longterm.putAll(this.eden); }finally{ lock.unlock(); } this.eden.clear(); } this.eden.put(k, v); } }