ibatis-FifoCache

核心代码

Deque<Object> keyList = new LinkedList<>();

为什么使用LinkedList？单向链表。
使用LinkedList实现FIFO，支持头、尾节点的单向链表。

添加时，判断数量大于初始化值时，删除头结点。

源码：

public class FifoCache implements Cache {

  private final Cache delegate;
  private final Deque<Object> keyList;
  private int size;

  public FifoCache(Cache delegate) {
    this.delegate = delegate;
    this.keyList = new LinkedList<>();
    this.size = 1024;
  }

  @Override
  public void putObject(Object key, Object value) {
    cycleKeyList(key);
    delegate.putObject(key, value);
  }private void cycleKeyList(Object key) {
    keyList.addLast(key);
    if (keyList.size() > size) {
      Object oldestKey = keyList.removeFirst();
      delegate.removeObject(oldestKey);
    }
  }

}