在这篇文章https://bbs.csdn.net/topics/390523873基础上改进的

public class KeyLock<K> {// 保存所有锁定的KEY及其信号量private final ConcurrentMap<K, Semaphore> map = new ConcurrentHashMap<K, Semaphore>();// 保存每个线程锁定的KEY及其锁定计数private final ThreadLocal<Map<K, LockInfo>> local = new ThreadLocal<Map<K, LockInfo>>() {@Overrideprotected Map<K, LockInfo> initialValue() {return new HashMap<K, LockInfo>();}};/*** 锁定key，其他等待此key的线程将进入等待，直到调用{@link #unlock(K)}* 使用hashcode和equals来判断key是否相同，因此key必须实现{@link #hashCode()}和* {@link #equals(Object)}方法* * @param key*/public void lock(K key) {if (key == null)return;LockInfo info = local.get().get(key);if (info == null) {Semaphore current = new Semaphore(1);current.acquireUninterruptibly();Semaphore previous = map.put(key, current);if (previous != null)previous.acquireUninterruptibly();local.get().put(key, new LockInfo(current));} else {info.lockCount++;}}/*** 释放key，唤醒其他等待此key的线程* @param key*/public void unlock(K key) {if (key == null)return;LockInfo info = local.get().get(key);if (info != null && --info.lockCount == 0) {info.current.release();map.remove(key, info.current);local.get().remove(key);}}/*** 锁定多个key* 建议在调用此方法前先对keys进行排序，使用相同的锁定顺序，防止死锁发生* @param keys*/public void lock(K[] keys) {if (keys == null)return;for (K key : keys) {lock(key);}}/*** 释放多个key* @param keys*/public void unlock(K[] keys) {if (keys == null)return;for (K key : keys) {unlock(key);}}private static class LockInfo {private final Semaphore current;private int lockCount;private LockInfo(Semaphore current) {this.current = current;this.lockCount = 1;}}
}