php 设计模式之 状态

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1. 模板模式

允许一个对象在其内部状态改变时改变它的行为。对象看起来似乎修改了它的类

2. 实列

class Member {
    private $state;
    private $score;

    public function SetState($state) {
        $this->state = $state;
    }

    public function SetScore($score) {
        $this->score = $score;
    }

    public function GetScore() {
        return $this->score;
    }

    public function discount() {
        return $this->state->discount($this);
    }
}

interface State {
    public function discount($member);
}

class PlatinumMemeberState implements State {
    public function discount($member) {
        if ($member->GetScore() >= 1000) {
            return 0.80;
        } else {
            $member->SetState(new GoldMemberState());
            return $member->discount();
        }
    }
}

class GoldMemberState implements State {
    public function discount($member) {
        if ($member->GetScore() >= 800) {
            return 0.85;
        } else {
            $member->SetState(new SilverMemberState());
            return $member->discount();
        }
    }
}

class SilverMemberState implements State {
    public function discount($member) {
        if ($member->GetScore() >= 500) {
            return 0.90;
        } else {
            $member->SetState(new GeneralMemberState());
            return $member->discount();
        }
    }
}

class GeneralMemberState implements State {
    public function discount($member) {
        return 0.95;
    }
}

$m = new Member();
$m->SetState(new PlatinumMemeberState());

$m->SetScore(1200);
echo '当前会员' . $m->GetScore() . '积分，折扣为：' . $m->discount(), PHP_EOL;

$m->SetScore(990);
echo '当前会员' . $m->GetScore() . '积分，折扣为：' . $m->discount(), PHP_EOL;

$m->SetScore(660);
echo '当前会员' . $m->GetScore() . '积分，折扣为：' . $m->discount(), PHP_EOL;

$m->SetScore(10);
echo '当前会员' . $m->GetScore() . '积分，折扣为：' . $m->discount(), PHP_EOL;

3. 使用场景

1. if...else... 判断