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  • (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);
        }
    }
    

      

     
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  • 原文地址:https://www.cnblogs.com/JsonShare/p/4012912.html
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