练习：用mysql建一张表来模拟memcache做缓存操作类，要求用到工厂模式，单件模式，适配器模式

cache.php

<?php

class Cache
{
	private static $instance = array();
	/**
	 * 缓存实例化的工厂方法并且确保单例
	 */
	public static function getInstance( $type,$options=array()){
		$type = strtolower(trim($type));
		
		if(isset(self::$instance[$type])){
			return self::$instance[$type];
		}
		$class = 'Cache'.ucwords($type);
		//class_exists 前提是已经有了自动载入机制
	        if(class_exists($class)){
	        	$cache = new $class($options);
	        	self::$instance[$type] = $cache;
	        }else{
	        	throw new Exception('error cache type'); 
	        }
	        return $cache;
	}

}

/**
 * 封装适配器接口规范
 */
interface CacheInterface
{
	function set($name, $value, $expire = null);

	function get($name);

	function delete($name);
}

abstract class CacheAbstract implements CacheInterface
{
	//设置默认的
	public $options = array('prefix'=>'zmk_','expire'=>'60');

}

class CacheApc extends CacheAbstract
{
	
	public function __construct($options=array()) {
		if(!function_exists('apc_cache_info')) {
			die('apc缓存扩展不存在');
		}
		$this->options = array_merge($this->options,$options);
	}


	public function get($name) {
		return apc_fetch($this->options['prefix'].$name);
	}

	public function set($name, $value, $expire = null) {
		if(is_null($expire)) {
            		$expire  =  $this->options['expire'];
        	}
        	$name   =   $this->options['prefix'].$name;
        	return apc_store($name, $value, $expire);
	}

	public function delete($name) {
		return apc_delete($this->options['prefix'].$name);
	}

	public function clear() {
        	return apc_clear_cache();
	}
}

$apc = Cache::getInstance('Cache',array('prefix'=>'zhoumengkang_'));
$apc->set('test','周梦康',60);
echo $apc->get('test');
var_dump($apc->options);


class CacheMemcache extends CacheAbstract
{
	private $handler;

	public function __construct($options=array()) {
		if(!extension_loaded('memcache')){
			die('memcache扩展不存在');
        	}
        	$this->options = array_merge($this->options,array('host'=>'localhost','port'=>'11211'),$options);
		$this->handler = new Memcache;
		$func          = $options['persistent'] ? 'pconnect' : 'connect';
	        if($options['timeout'] === false){
			$this->handler->$func($this->options['host'], $this->options['port']);
	        }else{
	        	$this->handler->$func($this->options['host'], $this->options['port'], $this->options['timeout']);
	        }
	}

	public function get($name) {
		return $this->handler->get($this->options['prefix'].$name);
	}

	public function set($name, $value, $expire = null) {
		if(is_null($expire)) {
			$expire  =  $this->options['expire'];
		}
		return $this->handler->set($this->options['prefix'].$name, $value, $expire);
	}

	public function delete($name,$timeout = null) {
		if(is_null($timeout)){
			return $this->handler->delete($this->options['prefix'].$name);
		}else{
			return $this->handler->delete($this->options['prefix'].$name,$timeout);
		}
	}

	public function clear() {
		return $this->handler->flush();
	}
}

//$memcache = new CacheMemcache(array('prefix'=>'haha_','persistent'=>true,'timeout'=>false));
$memcache = Cache::getInstance('memcache',array('prefix'=>'haha_','persistent'=>true,'timeout'=>false));
$memcache->set('test2','周梦康康梦周',60);
echo $memcache->get('test2');

class CacheMySQL extends CacheAbstract
{
	private $handler;

	public function __construct($options=array()) {
		if(!extension_loaded('pdo_mysql')){
			die('pdo_mysql扩展不存在');
        	}
        	$this->options = array_merge($this->options,array('host'=>'localhost','port'=>'3306'),$options);

		$this->handler = new PDO('mysql:host='.$this->options['host'].';port='.$this->options['port'].';dbname='.$this->options['database'], $this->options['user'], $this->options['password']);

		$this->handler->query("set names utf8");

	}

	public function get($name) {
		$name = $this->options['prefix'].$name;
		$sql  = "SELECT `cache_value` FROM `{$this->options['tablename']}` WHERE `cache_key` = '{$name}'";
		$res  = $this->handler->query($sql);
		foreach ($res as $row) {
			return $row['cache_value'];
		}
	}

	public function set($name, $value, $expire = null) {
		if(is_null($expire)) {
			$expire  =  $this->options['expire'];
		}
	        $name = $this->options['prefix'].$name;
	        $time = time();
	        $expire = $expire + time();//假设定时任务每秒请求执行一次autoDeleteCachePerSecond()
	
	        if($this->handler->query("SELECT * FROM `{$this->options['tablename']}` WHERE `cache_key` = '{$name}'")){
			$sql = "UPDATE `{$this->options['tablename']}` SET `cache_value` = '{$value}',`update_time` = {$time} ,`cache_time` = {$expire}";
	        }else{
	        	$sql = "INSERT INTO `{$this->options['tablename']}` (`cache_key`,`cache_value`,`create_time`,`cache_time`) VALUES('{$name}','{$value}',{$time},{$expire})";
	        }
	        
	        return $this->handler->exec($sql);
	}

	/**
	 * 每秒自动全表扫描删除该存活期等于该时间戳下的所有缓存数据
	 */
	public function autoDeleteCachePerSecond() {
		$sql = "DELETE FROM `{$this->options['tablename']}` WHERE `cache_time` = ".time();
		$this->handler->exec($sql);
	}

	public function delete($name) {
		$sql = "DELETE FROM `{$this->options['tablename']}` WHERE `cache_key` = '".$this->options['prefix'].$name."'";
		$this->handler->exec($sql);
	}

	public function clear() {
		$sql = "DELETE FROM `{$this->options['tablename']}`";
		$this->handler->exec($sql);
	}
}

//$mysqlCache = new CacheMySQL(array('database'=>'design_patterns','tablename'=>'mysql_cache_demo','user'=>'root','password'=>'zmkzmk'));
$mysqlCache = Cache::getInstance('Mysql',array('database'=>'design_patterns','tablename'=>'mysql_cache_demo','user'=>'root','password'=>'zmkzmk'));
$mysqlCache->set('mengkang','php_mysql_cache_test');
echo $mysqlCache->get('mengkang');