50行代码实现缓存,JAVA内存模型原理

 2019-12-10 15:51  阅读(1487)
文章分类:Java Core

遇见这样的高人怎么办??下面是一个简单缓存的实现,相当牛叉!自己看吧,只有50行代码。

摘自:http://www.oschina.net/code/snippet_55577_3887

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);
        }
    }
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