PHP里的單實例類在進行數(shù)據(jù)交換，節(jié)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();

}

}

最后是調用的地方：

$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());

最后的顯示結果：

string'SINGLEA CHANGED: ' (length=17)

int110

string'SINGLEB CHANGED: ' (length=17)

int-400