private string RemoveNode(LinkedHashListNode node)
{
if (node == _head && node == _last) //空表，没有节点可以移除
{
_head = null;
_last = null;
}
else if (node == _last) //移除最后一个节点
{
_last = _last.pre;
_last.next = null;
}
else if (node == _head) //移除第一个节点
{
_head = _head.next;
_head.pre = null;
}
else
{
node.pre.next = node.next;
node.next.pre = node.pre;
}
return(node.key);
}
private void RefreshNode(LinkedHashListNode node)
{
if (node == _last)
{
return;
}
RemoveNode(node);
AddNode(node);
}
private void AddNode(LinkedHashListNode node)
{
if (_last != null)
{
_last.next = node;
node.pre = node;
node.next = null;
}
_last = node;
if (_head == null)
{
_head = node;
}
}
public void Put(string key, string value)
{
if (!dict.TryGetValue(key, out LinkedHashListNode node))
{
if (dict.Count >= _capacity) //判断是否还有空余容量，如果没有就删除第一个节点
{
string oldKey = RemoveNode(_head);
dict.Remove(oldKey);
}
node = new LinkedHashListNode(key, value); //加入新节点
AddNode(node);
dict.Add(key, node);
}
else
{
node.value = value;
RefreshNode(node);
}
}
