设计模式1（简单工厂模式，策略模式）

<?php
/**
 简单工厂模式 
**/
abstract class CDb {
  abstract function connect();

  abstract function query();

}
class CMysqlDB extends CDb {
    function connect() {
	  echo 'mysql connect success';
	}
	function query() {
	  echo 'mysql query';
	} 
}

class CMssqlDb extends CDb {
   function connect() {
     echo 'mssql connect success';
   }
   function query() {
     echo 'mssql query';
   }
}

class DbManager {
  static function createDataBase($type) {
    $db = null;
    switch($type) {
       case 'mysql': 
	          $db = new CMysqlDB();
			  break;
	   case 'mssql':
	          $db = new CMssqlDb();
			  break; 
	  
	}
	return $db; 
  }
}

$type = 'mysql';

$db = DbManager::createDataBase($type);
$db->connect();
$db->query();


<?php
/**
 策略模式 
**/
abstract class CDb {
  abstract function connect();

  abstract function query();

}
class CMysqlDB extends CDb {
    function connect() {
	  echo 'mysql connect success';
	}
	function query() {
	  echo 'mysql query';
	} 
}

class CMssqlDb extends CDb {
   function connect() {
     echo 'mssql connect success';
   }
   function query() {
     echo 'mssql query';
   }
}

class DbManager {
  private $db;
  function createDataBase($type) {
    switch($type) {
       case 'mysql': 
	          $this->db = new CMysqlDB();
			  break;
	   case 'mssql':
	          $this->db = new CMssqlDb();
			  break; 
	  
	}
  }
  function getDb() {
    return $this->db;
  }
}

$dbmanager = new DbManager();
$dbmanager->createDataBase('mysql');
$dbmanager->getDb()->connect();