PDO支持数据缓存

/**
* 作者：初十
* QQ：345610000
*/
class myPDO extends PDO
{
public $cache_Dir = null; //缓存目录
public $cache_expireTime = 7200; //缓存时间，默认两小时

//带缓存的查询
public function cquery($sql)
{
//缓存存放总目录
if ($this->cache_Dir == null || !is_dir($this->cache_Dir)) {
   exit ("缓存目录有误！");
} else {
   $this->cache_Dir = str_replace("\", "/", $this->cache_Dir);
   $FileName = trim($this->cache_Dir, "/") . '/' . urlencode(trim($sql)) . '.sql';
}
//判断生成缓存
if (!file_exists($FileName) || time() - filemtime($FileName) > $this->cache_expireTime) {
   if ($tmpRS = parent::query($sql)) {
    $data = serialize($tmpRS->fetchAll());
    self::createFile($FileName, $data);
   } else {
    exit ("SQL语法错误<br />");
   }
}
return $this->readCache($FileName);
}

//读缓存文件
private static function readCache($FilePath)
{
if (is_file($FilePath) && $Data = file_get_contents($FilePath)) {
   return new cache_PDOStatement(unserialize($Data));
}
return false;
}

//生成文件
public static function createFile($FilePath, $Data = '')
{
if (file_put_contents($FilePath, $Data)) {
   return true;
} else {
   return false;
}
}
}
//缓存用到Statement类
class cache_PDOStatement
{
private $recordArr = array();
private $cursorId = 0;
private $recordCount = 0;

public function __construct($arr)
{
$this->recordArr = $arr;
$this->recordCount = count($arr);
}

//返回一条记录，指针下移一行
public function fetch()
{
if ($this->cursorId == $this->recordCount) {
   return false;
} else if ($this->cursorId == 0) {
   $this->cursorId++;
   return current($this->recordArr);
} else {
   $this->cursorId++;
   return next($this->recordArr);
}
}

//返回全部结果
public function fetchAll()
{
return $this->recordArr;
}

//单行单列查询
public function fetchColumn()
{
$tmpArr = current($this->recordArr);
return $tmpArr[0];
}
}

使用方法
$db = new myPDO('mysql: host = localhost;dbname=news','newsadmin','123456');

$db->cache_Dir = "cache"; //设置缓存目录
$db->cache_expireTime = 7200; //设置缓存时间

$rs = $db->cquery("select * from news limit 0,10"); //用缓存查询方法cquery代替query
while ($row = $rs->fetch()) {
echo $row["F_title"] . "<br />";
}

$rs = null;
$db = null;

补充：Php教程,Php高级应用