🕊? 中介者模式（Mediator Pattern）深度解析

——以Unity實現跨系統通信與復雜UI協調為核心案例

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一、模式本質與核心價值

核心目標：
? 解耦對象間的直接依賴，通過中介者集中管理交互
? 簡化網狀通信為星型結構，提升系統可維護性
? 統一控制交互邏輯，便于擴展新通信規則

關鍵術語：

• Mediator（中介者接口）：定義對象間通信的接口
• ConcreteMediator（具體中介者）：實現協調邏輯
• Colleague（同事類）：需要交互的對象，依賴中介者

數學表達：
設有N個對象，原始耦合度為O(N2)，引入中介者M后降為O(N)

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二、經典UML結構

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三、Unity實戰代碼（成就系統協調）

1. 定義中介者接口與同事基類

public interface IMediator {void Notify(object sender, string eventType, object data = null);
}public abstract class Colleague : MonoBehaviour {[SerializeField] protected IMediator mediator;public void SetMediator(IMediator mediator) {this.mediator = mediator;}
}

2. 實現具體同事類

// 成就系統
public class AchievementSystem : Colleague {public void Unlock(string achievementID) {Debug.Log($"解鎖成就：{achievementID}");mediator?.Notify(this, "AchievementUnlocked", achievementID);}
}// UI彈窗系統
public class UIPopup : Colleague {public void ShowAchievementPopup(string title) {Debug.Log($"顯示成就彈窗：{title}");}
}// 音效系統
public class SFXSystem : Colleague {public void Play(string clipName) {Debug.Log($"播放音效：{clipName}");}
}

3. 實現具體中介者

public class AchievementMediator : IMediator {private AchievementSystem _achievement;private UIPopup _popup;private SFXSystem _sfx;public AchievementMediator(AchievementSystem a, UIPopup u, SFXSystem s) {_achievement = a;_popup = u;_sfx = s;_achievement.SetMediator(this);_popup.SetMediator(this);_sfx.SetMediator(this);}public void Notify(object sender, string eventType, object data) {switch(eventType) {case "AchievementUnlocked":HandleAchievementUnlocked(data.ToString());break;case "PopupClosed":HandlePopupClosed();break;}}private void HandleAchievementUnlocked(string id) {_popup.ShowAchievementPopup(GetAchievementTitle(id));_sfx.Play("AchievementUnlocked");SaveSystem.SaveAchievement(id);}private void HandlePopupClosed() {_sfx.Play("ButtonClick");}
}

4. 客戶端使用

public class GameManager : MonoBehaviour {[SerializeField] private AchievementSystem achievement;[SerializeField] private UIPopup popup;[SerializeField] private SFXSystem sfx;private IMediator _mediator;void Start() {_mediator = new AchievementMediator(achievement, popup, sfx);}void Update() {if(Input.GetKeyDown(KeyCode.A)) {achievement.Unlock("KILL_100_ENEMIES");}}
}

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四、模式進階技巧

1. 事件總線集成

public class EventMediator : IMediator {private Dictionary<Type, List<Action<object>>> _handlers = new();public void Subscribe<T>(Action<T> handler) {var type = typeof(T);if(!_handlers.ContainsKey(type)) {_handlers[type] = new List<Action<object>>();}_handlers[type].Add(obj => handler((T)obj));}public void Notify(object sender, string eventType, object data) {if(_handlers.TryGetValue(data.GetType(), out var handlers)) {foreach(var h in handlers) h(data);}}
}

2. 狀態依賴管理

public class StateDependentMediator : IMediator {private Dictionary<GameState, Action<object>> _stateHandlers = new();public void RegisterStateHandler(GameState state, Action<object> handler) {_stateHandlers[state] = handler;}public void Notify(object sender, string eventType, object data) {if(_stateHandlers.TryGetValue(GameManager.CurrentState, out var handler)) {handler(data);}}
}

3. 優先級路由

public class PriorityMediator : IMediator {private List<(int priority, Action<object>)> _handlers = new();public void AddHandler(int priority, Action<object> handler) {_handlers.Add((priority, handler));_handlers.Sort((a,b) => b.priority.CompareTo(a.priority));}public void Notify(object sender, string eventType, object data) {foreach(var h in _handlers) {h.handler(data);}}
}

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五、游戲開發典型應用場景

1. UI系統協調

   public class UIMediator : IMediator {public void Notify(object sender, string eventType) {switch(eventType) {case "InventoryOpened":PauseGame();HideHUD();break;case "SettingsClosed":ResumeGame();ShowHUD();break;}}
   }
   

2. 多人游戲同步

   public class NetworkMediator : IMediator {public void Notify(object sender, string eventType, object data) {switch(eventType) {case "PlayerMove":BroadcastToAllClients(data);break;case "ChatMessage":ProcessChatMessage(data);break;}}
   }
   

3. 任務系統協調

   public class QuestMediator : IMediator {public void Notify(object sender, string eventType, Quest quest) {switch(eventType) {case "QuestStarted":UpdateQuestLog();PlayQuestStartSFX();break;case "QuestCompleted":GrantRewards();UpdateNPCdialogue();break;}}
   }
   

4. 車輛控制系統

   public class VehicleMediator : IMediator {public void Notify(object sender, string eventType) {if(sender is Engine && eventType == "Overheat") {ThrottleControl.ReducePower();CoolingSystem.ActivateEmergencyCooling();}}
   }
   

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六、性能優化策略

策略	實現方式	適用場景
事件過濾	提前終止不相關事件處理	高頻事件系統
批處理	合并多個通知為單個操作	物理系統更新
緩存路由表	預生成事件處理映射	固定事件類型
異步處理	使用UniTask處理耗時操作	網絡通信場景

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七、模式對比與選擇

維度	中介者模式	觀察者模式
關注點	集中協調	松散通知
耦合度	同事類依賴中介者	發布者/訂閱者解耦
復雜度	較高（需維護中介者）	較低
典型場景	復雜交互協調	簡單事件通知

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八、最佳實踐原則

1. 職責分離：避免中介者成為"上帝對象"
2. 接口最小化：

   public interface IGameMediator {void PlayerAction(PlayerActionType action);void UIEvent(UIEventType event);
   }
   

3. 模塊化中介者：

   public class CompositeMediator : IMediator {private List<IMediator> _subMediators = new();public void AddMediator(IMediator m) => _subMediators.Add(m);public void Notify(object sender, string eventType, object data) {foreach(var m in _subMediators) m.Notify(sender, eventType, data);}
   }
   

4. 異常隔離：

   public void Notify(...) {try {// 處理邏輯} catch(Exception e) {Debug.LogError($"中介者處理異常：{e.Message}");}
   }
   

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九、常見問題解決方案

Q1：如何防止中介者過度膨脹？
→ 實現分層中介者

public class HierarchyMediator : IMediator {private Dictionary<SystemType, IMediator> _subMediators = new();public void Notify(...) {if(_subMediators.TryGetValue(GetSystemType(sender), out var mediator)) {mediator.Notify(sender, eventType, data);}}
}

Q2：如何處理循環通知？
→ 實現事件標記

public class Notification {public string Type;public bool IsProcessed;
}public void Notify(...) {if(notification.IsProcessed) return;notification.IsProcessed = true;// 處理邏輯
}

Q3：如何調試復雜事件流？
→ 實現事件追蹤器

public class DebugMediator : IMediator {public void Notify(object sender, string eventType, object data) {Debug.Log($"[{Time.time}] 事件：{eventType} 發送者：{sender.GetType().Name}");// 傳遞給實際中介者...}
}

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