dubbo --- LRUCache简单实现
import java.util.LinkedHashMap;import java.util.concurrent.locks.Lock;import java.util.concurrent.locks.ReentrantLock;public class LRUCache<K, V> extends LinkedHashMap<K, V> {private static final long serialVersionUID = -5167631809472116969L;private static final float DEFAULT_LOAD_FACTOR = 0.75f;private static final int DEFAULT_MAX_CAPACITY = 1000;private volatile int maxCapacity;private final Lock lock = new ReentrantLock(); public LRUCache() { this(DEFAULT_MAX_CAPACITY); } public LRUCache(int maxCapacity) { super(16, DEFAULT_LOAD_FACTOR, true); this.maxCapacity = maxCapacity; } @Override protected boolean removeEldestEntry(java.util.Map.Entry<K, V> eldest) { return size() > maxCapacity; } @Override public boolean containsKey(Object key) { try { lock.lock(); return super.containsKey(key); } finally { lock.unlock(); } } @Override public V get(Object key) { try { lock.lock(); return super.get(key); } finally { lock.unlock(); } } @Override public V put(K key, V value) { try { lock.lock(); return super.put(key, value); } finally { lock.unlock(); } } @Override public V remove(Object key) { try { lock.lock(); return super.remove(key); } finally { lock.unlock(); } } @Override public int size() { try { lock.lock(); return super.size(); } finally { lock.unlock(); } } @Override public void clear() { try { lock.lock(); super.clear(); } finally { lock.unlock(); } }public int getMaxCapacity() {return maxCapacity;}public void setMaxCapacity(int maxCapacity) {this.maxCapacity = maxCapacity;}}?
利用LinkedHashMap扩展实现简单的LRUCache，主要两点：
1.重写removeEldestEntry方法，决定何时移除最旧条目
2.关键方法加锁，如put、get
?
?
说明：
加载因子：
?
?