设计模式——备忘录模式

说明

示例

下面看下备忘录模式的代码实现

class Original{
    private string $value;

    public function __construct(string $value){
        $this->value = $value;
    }

    public function getValue(): string{
        return $this->value;
    }

    public function setValue(string $value){
        $this->value = $value;
    }

    public function createMemento(): Memento{
        return new Memento($this->value);
    }

    public function restoreMemento(Memento $memento){
        $this->value = $memento->getValue();
    }
}

class Memento{
    private string $value;

    public function __construct(string $value){
        $this->value = $value;
    }

    public function getValue(): string{
        return $this->value;
    }

    public function setValue(string $value){
        $this->value = $value;
    }
}

class Storage{
    private Memento $memento;

    public function __construct(Memento $memento){
        $this->memento = $memento;
    }

    public function getMemento(): Memento{
        return $this->memento;
    }

    public function setMemento(Memento $memento){
        $this->memento = $memento;
    }
}


// 调用
$origi = new Original("egg");
$storage = new Storage($origi->createMemento());

echo "初始化状态为：" . $origi->getValue() . PHP_EOL;
$origi->setValue("niu");
echo "修改后的状态为：" . $origi->getValue() . PHP_EOL;

$origi->restoreMemento($storage->getMemento());
echo "恢复后的状态为：" . $origi->getValue() . PHP_EOL;
/**
 * output:
 * 初始化状态为：egg
 * 修改后的状态为：niu
 * 恢复后的状态为：egg
 * 
 */

总结