Java LocalCache 本地缓存的实现实例

  static {
    timer = new Timer();
    map = new ConcurrentHashMap<>();
  }

  private LocalCache() {

  }

  /**
   * 清除缓存任务类
   */
  static class CleanWorkerTask extends TimerTask {

    private String key;

    public CleanWorkerTask(String key) {
      this.key = key;
    }

    public void run() {
      LocalCache.remove(key);
    }
  }

static class LRUMap<K, V> extends LinkedHashMap<K, V> {

    ... // 省略部分代码

    public LRUMap(int initialCapacity, float loadFactor) {
      super(initialCapacity, loadFactor, true);
    }

    ... // 省略部分代码

    /**
     * 重写LinkedHashMap中removeEldestEntry方法;
     * 新增元素的时候,会判断当前map大小是否超过DEFAULT_MAX_CAPACITY,超过则移除map中最老的节点;
     *
     * @param eldest
     * @return
     */
    protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
      return size() > DEFAULT_MAX_CAPACITY;
    }

  }

 /**
     * 读写锁
     */
    private final ReadWriteLock readWriteLock = new ReentrantReadWriteLock();

    private final Lock rLock = readWriteLock.readLock();

    private final Lock wLock = readWriteLock.writeLock();

 protected boolean removeEldestEntry(Map.Entry<K, V> eldest) {
      return size() > DEFAULT_MAX_CAPACITY;
    }