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();
希望本文所述对大家PHP程序设计有所帮助。