PHP裡的單實例類在進行數據交換,節省內存上還是很有意義的。寫個簡單例子。
類1,單實例類本身:
class UTIL { private static $instance; public function get() { if (!self::$instance) { self::$instance = new UTIL(); } return self::$instance; } public $number = 10; public function change($num) { $this->number += $num; } public function getNum() { return $this->number; } }
類2,使用前述單實例類的應用類:
class SINGLEA { private $numInst; function __construct() { $this->numInst = UTIL::get(); } public function change($num) { $this->numInst->change($num); } public function getNum() { return $this->numInst->getNum(); } }
類3,同類2:
class SINGLEB { private $numInst; function __construct() { $this->numInst = UTIL::get(); } public function change($num) { $this->numInst->change($num); } public function getNum() { return $this->numInst->getNum(); } }
最後是調用的地方:
$instA = new SINGLEA(); $instA->change(100); var_dump('SINGLEA CHANGED: '); var_dump($instA->getNum()); $instB = new SINGLEB(); $instB->change(-510); var_dump('SINGLEB CHANGED: '); var_dump($instB->getNum());
最後的顯示結果:
string'SINGLEA CHANGED: ' (length=17) int110 string'SINGLEB CHANGED: ' (length=17) int-400