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The http common module of microservice project

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package com.github.ibole.microservice.common.utils;

import java.util.LinkedHashMap;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 利用LinkedHashMap实现简单的LRU缓存， 必须实现removeEldestEntry方法.
 * 
 * @author bwang
 *
 * @param  the type of key
 * @param  the type of value
 */
public class LRUCache extends LinkedHashMap {

  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 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;
  }

}