本文实例讲述了PHP设计模式之工厂模式与单例模式实现方法。分享给大家供大家参考，具体如下：
设计模式简单说应对某类问题而设计的解决方式
工厂模式：应对需求创建相应的对象
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class factory{ function __construct($name){ if(file_exists('./'.$name.'.class.php')){ return new $name; }else{ die('not exist'); } }} |
单例模式：只创建一个对象的实例，不允许再创建实例，节约资源（例如数据库的连接）
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class instance{ public $val = 10; private static $instance ; private function __construct(){} private function __clone(){} //设置为静态方法才可被类调用 public static function getInstance(){ /*if(!isset(self::$instance)){ self::$instance = new self; }*/ if(!isset(instance::$instance)){ instance::$instance = new self; } return instance::$instance; }}$obj_one = instance::getInstance();$obj_one->val = 20;//clone可以调用__clone()克隆即new出一个新的的对象//$obj_two = clone $obj_one;$obj_two = instance::getInstance();echo $obj_two->val;echo '<p>';var_dump($obj_one,$obj_two); |
运行结果如下：
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20object(instance)[1] public 'val' => int 20object(instance)[1] public 'val' => int 20 |
应用：数据库连接类（database access oject）
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class mysqldb{ private $arr = array( 'port' => 3306, 'host' => 'localhost', 'username' => 'root', 'passward' => 'root', 'dbname' => 'instance', 'charset' => 'utf8' ); private $link; static $instance; private function __clone(){} private function __construct(){ $this->link = mysql_connect($this->arr['host'],$this->arr['username'],$this->arr['passward']) or die(mysql_error()); mysql_select_db($this->arr['dbname']) or die('db error'); mysql_set_charset($this->arr['charset']); } static public function getInsance(){ if(!isset(mysqldb::$instance)){ mysqldb::$instance = new self; } return mysqldb::$instance; } public function query($sql){ if($res = mysql_query($sql)){ return $res; }return false; } //fetch one public function get_one($sql){ $res = $this->query($sql); if($result = mysql_fetch_row($res)){ return $result[0]; } } //fetch row public function get_row($sql){ $res = $this->query($sql); if($result = mysql_fetch_assoc($res)){ return $result; } return false; } //fetch all public function get_all($sql){ $res = $this->query($sql); $arr = array(); while($result = mysql_fetch_assoc($res)){ $arr[] = $result; } return $arr; }}$mysql = mysqldb::getInsance(); |
希望本文所述对大家PHP程序设计有所帮助。
