PHP设计模式之工厂模式与单例模式

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

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

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）

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：

20
object(instance)[1]
 public 'val' => int 20
object(instance)[1]
 public 'val' => int 20

应用：数据库连接类（database access oject）

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();