Zend Framework中的简单工厂模式 图文

$db = Zend_Db::factory('Pdo_Mysql', array(
'host' => '127.0.0.1',
'username' => 'webuser',
'password' => 'xxxxxxxx',
'dbname' => 'test'
));

$db->setFetchMode(Zend_Db::FETCH_OBJ);
$result = $db->fetchAssoc(
'SELECT bug_id, bug_description, bug_status FROM bugs'
);

< ?php
class 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, $config = array())
{
//使用Zend_Config对象，上述方式没有使用，直接使用Array
if ($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;
}
}

//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);

$db = Zend_Db::factory('Pdo_Mysql', array(
'host' => '127.0.0.1',
'username' => 'webuser',
'password' => 'xxxxxxxx',
'dbname' => 'test'
));