PHP 設計模式實戰：投訴處理系統多模式綜合範例

本文透過一個「使用者投訴舉報系統」實例，示範 8 種經典設計模式在實際業務中的組合應用，涵蓋建構型、結構型、行為型三大類，展示如何透過模式解耦業務邏輯、提升擴充性。

業務場景與模式對應表

核心程式碼實作

1. 單例 + 工廠：資料庫連線

interface DB { public function conn(); }

class MysqlSingle implements DB {
    private static $instance = null;
    private function __construct() { echo "Mysql單例建立成功
"; }
    private function __clone() {}
    public static function getInstance() {
        if (!self::$instance instanceof self) self::$instance = new self();
        return self::$instance;
    }
    public function conn() { echo "Mysql連線成功
"; }
}

interface Factory { public function createDB(); }
class MysqlFactory implements Factory {
    public function createDB() {
        echo "Mysql工廠建立成功
";
        return MysqlSingle::getInstance();
    }
}

2. 觀察者：用戶風格通知

class Observer implements SplSubject {
    private $observers;
    public $style;
    public function __construct($style) {
        $this->style = $style;
        $this->observers = new SplObjectStorage();
    }
    public function attach(SplObserver $o) { $this->observers->attach($o); }
    public function detach(SplObserver $o) { $this->observers->detach($o); }
    public function notify() {
        foreach ($this->observers as $o) $o->update($this);
    }
    public function show() { $this->notify(); }
}

class StyleA implements SplObserver {
    public function update(SplSubject $s) { echo $s->style . " 模組A
"; }
}
class StyleB implements SplObserver {
    public function update(SplSubject $s) { echo $s->style . " 模組B
"; }
}

3. 橋接：管道 × 等級 組合

abstract class Bridge {
    protected $impl;
    public function __construct($impl) { $this->impl = $impl; }
    abstract public function msg();
    public function show() { $this->msg(); $this->impl->msg(); }
}
class BridgeEmail extends Bridge { public function msg() { echo "Email>>"; } }
class BridgeSms extends Bridge { public function msg() { echo "Sms>>"; } }

class Normal { public function msg() { echo "Normal
"; } }
class Danger { public function msg() { echo "Danger
"; } }

// 使用：new BridgeEmail(new Danger())->show(); // Email>>Danger

4. 適配器：序列化格式轉換

class Serialize {
    public $content;
    public function __construct($content) { $this->content = serialize($content); }
    public function show() { return "序列化格式:
" . $this->content; }
}
class JsonAdapter extends Serialize {
    public function __construct($content) {
        parent::__construct($content);
        $this->content = json_encode(unserialize($this->content), JSON_UNESCAPED_UNICODE);
    }
    public function show() { return "JSON格式:
" . $this->content; }
}

5. 裝飾器：自動附加時間

class Base { protected $content; public function __construct($c) { $this->content = $c; } public function get() { return $this->content; } }
class Decorator {
    private $base;
    public function __construct(Base $b) { $this->base = $b; }
    public function show() { return $this->base->get() . ">>系統時間:" . date('Y-m-d H:i:s'); }
}

6. 責任鏈：分級處理

class Level1 { protected $level=1; protected $next='Level2'; 
    public function deal($l) { if($l<=$this->level){echo "處理級別:1
";return;} (new $this->next)->deal($l); } }
class Level2 { protected $level=2; protected $next='Level3'; 
    public function deal($l) { if($l<=$this->level){echo "處理級別:2
";return;} (new $this->next)->deal($l); } }
class Level3 { protected $level=3; 
    public function deal($l) { echo "處理級別:3
"; } }

前端表單觸發

  用戶名: TomLily

  投訴等級: NormalDanger
  通知管道: EmailSms
  處理層級: 123
  投訴內容: 
  送出

控制器整合邏輯

if ($_POST) {
    // 1. 工廠+單例建立連線
    $db = (new MysqlFactory())->createDB(); $db->conn();
    
    // 2. 觀察者通知風格模組
    $obs = new Observer($_POST['username']);
    $obs->attach(new StyleA()); $obs->attach(new StyleB());
    $obs->show(); $obs->detach(new StyleB()); $obs->show();
    
    // 3. 橋接組合管道與等級
    $bridge = "Bridge{$_POST['typeN']}";
    $level = $_POST['typeM'];
    (new $bridge(new $level()))->show();
    
    // 4. 適配器輸出多格式
    $ser = new Serialize($_POST); echo $ser->show();
    $json = new JsonAdapter($_POST); echo $json->show();
    
    // 5. 裝飾器附加時間
    echo (new Decorator(new Base($_POST['content'])))->show();
    
    // 6. 責任鏈分級處理
    (new Level1())->deal((int)$_POST['level']);
    exit;
}

模式組合心得

• 單一職責：每個類別只處理一項核心邏輯（連線、格式、流程、通知）
• 開放封閉：新增管道（如 Line Notify）只需新增 BridgeLine 類別，不修改既有碼
• 依賴倒置：高層流程（控制器）依賴抽象介面，而非具體實作
• 實務取捨：小專案無需強行套用所有模式；核心變動頻繁的子系統（如通知管道、處理流程）優先導入

此範例展示設計模式非孤立存在，而是透過組合解決真實業務複雜度。讀者可嘗試擴充：加入「策略模式」計算經驗值、「模板方法」統一投訴處理骨架、「狀態模式」管理投訴狀態流轉。