概念
LRU ： 最近最少使用算法

代碼

<?php class Node {public $preKey = null; //鏈表前一個節(jié)點public $nextKey = null; //鏈表后一個節(jié)點public $key= null; //當前的值public $value= null; //當前keypublic function __construct($key,$value){$this->key = $key;$this->value = $value;}public function setPre($preKey){$this->preKey = $preKey;}public function setNext($nextKey){$this->nextKey = $nextKey;} }class LRUCache{public $cacheTable = [];/** Node null */private $headNode = null;private $lastNode = null;private $cacheCount = 0;private $cacheMax = 3;public function addNode($key,$value) //此處采用頭插法{$addNode = new Node($key,$value);if ( !empty($this->headNode)){$this->headNode->preKey = $addNode; //如果鏈表存在，將節(jié)點添加到節(jié)點前一個}$addNode->nextKey = $this->headNode;//第一次保存最后一個節(jié)點為頭結(jié)點if ($this->lastNode == null){$this->lastNode = $addNode;}$this->headNode = $addNode;$this->cacheTable[$key] = $addNode;$this->cacheCount++;}public function set($key,$value){//先判斷是否需要刪除$this->shiftNode();$this->addNode($key,$value);return true;}//自動刪除public function shiftNode(){while ($this->cacheCount >= $this->cacheMax){if (!empty($this->lastNode)){if ($this->lastNode->preKey){$this->lastNode->preKey->nextKey = null;$this->lastNode = $this->lastNode->preKey;}unset($this->cacheTable[$this->lastNode->key]);}$this->cacheCount --;}}public function dumpAllData(){$node = $this->headNode;while (($node)){echo "key=".$node->key."value=".$node->value."\n";$node = $node->nextKey;}}}$Cache = new LRUCache(); $Cache->set("a","aaaaaaaaaaa"); $Cache->set("b","bbbbbbbbbbb"); $Cache->set("c","ccccccccccc"); $Cache->set("d","dddddddddddd"); $Cache->set("e","eeeeeeeeeeee"); //$Cache->set("f","ffffffffffff"); $Cache->dumpAllData(); //var_dump($Cache); //是一個深度的數(shù)組（對象）

結(jié)果

[root@VM-16-13-centos ~]# php LRU.php key=evalue=eeeeeeeeeeee key=dvalue=dddddddddddd key=cvalue=ccccccccccc

總結(jié)

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