PHP里的单实例类在进行数据交换,节省内存上还是很有意义的。写个简单例子。

类1,单实例类本身:

[codesyntax lang="php"]

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;
    }
}

[/codesyntax]

类2,使用前述单实例类的应用类:

[codesyntax lang="php"]

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();
    }
}

[/codesyntax]

类3,同类2:

[codesyntax lang="php"]

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();
    }
}

[/codesyntax]

最后是调用的地方:

[codesyntax lang="php"]

$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());

[/codesyntax]

最后的显示结果:

string'SINGLEA CHANGED: ' (length=17)
int110
string'SINGLEB CHANGED: ' (length=17)
int-400