LRUCache

package com.alibaba.dubbo.common.utils;

 

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;

}

 

}