前段时间用Zend Framework,把他当黑盒感觉不是很好,一直有看其源码的冲动,但是。。。如果一点一点地看的话,挑战确实有些大了。要说模式,暂时不知道是不是所有模式ZF里面都有,但是应该有足够的模式够我最近看了,在说可以找找其他开源的软件来找模式。这段时间被各种笔试神马乱七八糟的把生活搞得稍微有点乱,但是不管怎样,复习还是必须的吧。再说一下ZF吧,ZF一个好处就是各个component比较独立,component之间没有过多的依赖,这样一来,为使用者提供了方便,当然也为我这样无聊且懒的想看源码的人提供了方便。
今天看看简单工厂,ZF里面不缺模式,更不缺工厂模式,大名鼎鼎的的 Zend_Db就毫不吝啬的使用简单工厂,再ctrl+h(zend studio下)一下会发现factory特别多,如果没猜错应该大多应该也是简单工厂。由于Zend_Db 最常用,我也就自然的会比较想看一下他的实现。在查看源码之前先复习一下怎么用Zend_Db和简单工厂(这里是一个stack,先复习简单工厂)。
复习简单工厂模式
用类图回忆一下,简单工厂类图:
如果不知道如何使用,准备看XXX的源码却不知道怎么用XXX,这有点囧,所以先小小的看一下Zend_Db的使用,下面这段是在ZF官方文档里面的(个人不是很喜欢ZF文档,没Yii易读)
/public/index.php
$db = Zend_Db::factory(‘Pdo_Mysql’, array(‘host’ => ‘127.0.0.1’,‘username’ => ‘webuser’,‘password’ => ‘xxxxxxxx’,‘dbname’ => ‘test’));
上面生成了一个$db(一个Zend_Db对象),使用上面的$db进行查询如下:
$db->setFetchMode(Zend_Db::FETCH_OBJ);$result = $db->fetchAssoc(
‘SELECT bug_id, bug_description, bug_status FROM bugs’);
<?phpclass Zend_Db{/**设定一些常量和默认值*//*** Factory for Zend_Db_Adapter_Abstract classes.** First argument may be a string containing the base of the adapter class* name, e.g. ‘Mysqli’ corresponds to class Zend_Db_Adapter_Mysqli. This* name is currently case-insensitive, but is not ideal to rely on this behavior.* If your class is named ‘My_Company_Pdo_Mysql’, where ‘My_Company’ is the namespace* and ‘Pdo_Mysql’ is the adapter name, it is best to use the name exactly as it* is defined in the class. This will ensure proper use of the factory API.** First argument may alternatively be an object of type Zend_Config.* The adapter class base name is read from the ‘adapter’ property.* The adapter config parameters are read from the ‘params’ property.** Second argument is optional and may be an associative array of key-value* pairs. This is used as the argument to the adapter constructor.** If the first argument is of type Zend_Config, it is assumed to contain* all parameters, and the second argument is ignored.** @param mixed $adapter String name of base adapter class, or Zend_Config object.* @param mixed $config OPTIONAL; an array or Zend_Config object with adapter parameters.* @return Zend_Db_Adapter_Abstract* @throws Zend_Db_Exception*/public static function factory ($adapter, $config = array()){//使用Zend_Config对象,上述方式没有使用,直接使用Arrayif ($config instanceof Zend_Config) {$config = $config->toArray();}/** Convert Zend_Config argument to plain string* adapter name and separate config object.*/if ($adapter instanceof Zend_Config) {if (isset($adapter->params)) {$config = $adapter->params->toArray();}if (isset($adapter->adapter)) {$adapter = (string) $adapter->adapter;} else {$adapter = null;}}/** Verify that adapter parameters are in an array.*/if (! is_array($config)) {/*** @see Zend_Db_Exception*/require_once ‘Zend/Db/Exception.php’;throw new Zend_Db_Exception(‘Adapter parameters must be in an array or a Zend_Config object’);}/** Verify that an adapter name has been specified.*/if (! is_string($adapter) || empty($adapter)) {/*** @see Zend_Db_Exception*/require_once ‘Zend/Db/Exception.php’;throw new Zend_Db_Exception(‘Adapter name must be specified in a string’);}/** Form full adapter class name*/$adapterNamespace = ‘Zend_Db_Adapter’;if (isset($config[‘adapterNamespace’])) {if ($config[‘adapterNamespace’] != ”) {$adapterNamespace = $config[‘adapterNamespace’];}unset($config[‘adapterNamespace’]);}// Adapter no longer normalized- see http://framework.zend.com/issues/browse/ZF-5606$adapterName = $adapterNamespace . ‘_’;$adapterName .= str_replace(‘ ‘, ‘_’,ucwords(str_replace(‘_’, ‘ ‘, strtolower($adapter))));/** Load the adapter class. This throws an exception* if the specified class cannot be loaded.*/if (! class_exists($adapterName)) {require_once ‘Zend/Loader.php’;Zend_Loader::loadClass($adapterName);}/** Create an instance of the adapter class.* Pass the config to the adapter class constructor.*/$dbAdapter = new $adapterName($config);/** Verify that the object created is a descendent of the abstract adapter type.*/if (! $dbAdapter instanceof Zend_Db_Adapter_Abstract) {/*** @see Zend_Db_Exception*/require_once ‘Zend/Db/Exception.php’;throw new Zend_Db_Exception(“Adapter class ‘$adapterName’ does not extend Zend_Db_Adapter_Abstract”);}return $dbAdapter;}}?>
最上方的注释非常值得看,它清楚的说明了这个工厂,另外一段比较重要的几段代码(忽略其中的异常处理)是:
//factory有一个参数叫做$adapter
public static function factory($adapter, $config = array())
//确定namespace
$adapterNamespace = ‘Zend_Db_Adapter’;
//用namespace和上面传入的$adapter构造类名
$adapterName = $adapterNamespace . ‘_’;
$adapterName .= str_replace(‘ ‘, ‘_’, ucwords(str_replace(‘_’, ‘ ‘, strtolower($adapter))));
//用上面生成的类名new出obj,看起来PHP比java方便那么一点点哈(Class.forName(‘XXX’).newInstance())
$dbAdapter = new $adapterName($config);
在回想上面使用Zend_Db::factory生成$db的地方:
$db = Zend_Db::factory(‘Pdo_Mysql’, array(
‘host’ => ‘127.0.0.1’,
‘username’ => ‘webuser’,
‘password’ => ‘xxxxxxxx’,
‘dbname’ => ‘test’
));
factory方法的第一个参数即是$adapter为Pdo_Mysql,记住这里是Pdo_Mysql,再跳跃一下,根据上面的$adapterNamespace = ‘Zend_Db_Adapter’;可以看到生成的找到$dbAdapter的值最终必为:Zend_Db_Adapter_Pdo_Mysql,ok,根据此名字找到zend/db/adapter/pdo目录下,哈,这么多熟悉的面孔,看到了熟悉的MySql、Mssql、Sqlite这些老面孔了。
注意,注意,里面还有个低调的Abstract.php,里面他们的父类Zend_Db_Adapter_Pdo_Abstract。打开Mysql.php可以看到
class Zend_Db_Adapter_Pdo_Mysql extends Zend_Db_Adapter_Pdo_Abstract
嗯,类名Zend_Db_Adapter_Pdo_Mysql和上面生成的名字一样滴,在看看其他几个文件里面的类,他们都继承自Zend_Db_Adapter_Pdo_Abstract,如果要画类图,那就应该会有如下这么一张类图:
接着再加入调用着Client和工厂函数所在的位置Zend_Db,这张简单的类图就应该是,
一个非常非常纯净的简单工厂就这么出来了(不像简单工厂类图吗?那只是因为类的位置没放好)。
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