//测试
 $cache = new Cache();
 $cache->dir = "../cc/";
 //$cache->setCache("zhang", "zhangsan", 100);
 echo $cache->getCache("zhang");
 //$cache->removeCache("zhang");
 
 $cache->setCache("liu", "liuqi", 100);
 echo $cache->getCache("liu");

 class Cache{
 public $cacheFile = "cache.json"; //文件
 public $dir = "./cach2/"; //目录

 //缓存
 public function setCache($name, $val, $expires_time){
 $file = $this->hasFile();
 //字符串转数组
 $str = file_get_contents($file);
 $arr = json_decode($str, true);
 
 //值为空，则移除该缓存
 if(empty($val)){
 unset($arr[$name]);
 }else{
 $arr[$name] = array("value"=>$val, "expires_time"=>$expires_time, "add_time"=>time());
 } 
 //数组转字符串
 $str = json_encode($arr);
 file_put_contents($file, $str);
 }
 public function getCache($name){
 $file = $this->hasFile();
 
 //字符串转数组
 $allArr = json_decode($str, true);
 $arr = $allArr[$name];

 if(!$arr || time() > ($arr["expires_time"] + $arr["add_time"])){
 $this->removeCache($name); //过期移除
 return false;
 }
 return $arr["value"];
 }
 public function removeCache($name){
 $this->setCache($name, '', 0);
 }
 
 private function hasFile(){
 //如果不存在缓存文件，则创建一个
 if(!file_exists($this->dir)){
 mkdir($this->dir);
 }
 if(!file_exists($this->dir . $this->cacheFile)){
 touch($this->dir . $this->cacheFile);
 }
 return $this->dir . $this->cacheFile;
 }
}