Unity 观察者模式（实例详解）-编程知识

文章目录

- 简介
- - 示例1 - 简单的文本更新通知
  - 示例2 - 多观察者监听游戏分数变化
  - 示例3 - 事件系统实现观察者模式
  - 示例4 - 泛型观察者和可序列化的事件系统
  - 示例5 - 使用C#委托简化版

简介

在Unity中实现观察者模式，我们可以创建一个Subject（目标/主题）类，它负责维护订阅者列表，并且当其状态改变时通知所有观察者。下面通过5个代码示例来详细展示如何在Unity C#脚本中应用观察者模式：

示例1 - 简单的文本更新通知

using System.Collections;
using System.Collections.Generic;// 观察者接口
public interface IObserver
{void OnUpdate(string message);
}// 被观察者接口
public interface IObservable
{void Register(IObserver observer);void Remove(IObserver observer);void NotifyObservers(string message);
}// 具体的被观察者类
public class TextDisplay : MonoBehaviour, IObservable
{private List<IObserver> observers = new List<IObserver>();public void Register(IObserver observer){observers.Add(observer);}public void Remove(IObserver observer){observers.Remove(observer);}public void NotifyObservers(string message){foreach (var observer in observers){observer.OnUpdate(message);}}// 模拟状态改变public void UpdateText(string newText){Debug.Log("Text has been updated to: " + newText);NotifyObservers(newText);}
}// 具体的观察者类
public class ConsoleLogger : MonoBehaviour, IObserver
{public void OnUpdate(string message){Debug.Log("Console Logger received update: " + message);}
}// 使用示例
public class GameManager : MonoBehaviour
{public TextDisplay display;public ConsoleLogger logger;void Start(){display.Register(logger);display.UpdateText("Hello, World!");}
}

示例2 - 多观察者监听游戏分数变化

public interface IScoreObserver : IObserver
{void OnScoreChanged(int newScore);
}public class ScoreManager : MonoBehaviour, IObservable
{private List<IScoreObserver> scoreObservers = new List<IScoreObserver>();public void Register(IScoreObserver observer){scoreObservers.Add(observer);}public void Remove(IScoreObserver observer){scoreObservers.Remove(observer);}public void NotifyScoreObservers(int newScore){foreach (var observer in scoreObservers){observer.OnScoreChanged(newScore);}}public void IncreaseScore(int points){int currentScore = GetTotalScore(); // 假设这是一个获取当前分数的方法int newScore = currentScore + points;SetTotalScore(newScore); // 假设这是一个设置总分数的方法NotifyScoreObservers(newScore);}
}public class ScoreUI : MonoBehaviour, IScoreObserver
{public void OnScoreChanged(int newScore){GetComponent<Text>().text = "Score: " + newScore;}
}public class HighScoreTracker : MonoBehaviour, IScoreObserver
{public void OnScoreChanged(int newScore){if (newScore > PlayerPrefs.GetInt("HighScore")){PlayerPrefs.SetInt("HighScore", newScore);}}
}// 使用示例
public class GameInitializer : MonoBehaviour
{public ScoreManager scoreManager;public ScoreUI scoreUI;public HighScoreTracker highScoreTracker;void Start(){scoreManager.Register(scoreUI);scoreManager.Register(highScoreTracker);// 游戏过程中调用scoreManager.IncreaseScore()增加分数}
}

示例3 - 事件系统实现观察者模式

using UnityEngine.Events;public class SubjectWithEvent : MonoBehaviour
{public UnityEvent<string> OnTextUpdated;public void UpdateText(string newText){Debug.Log("Text has been updated to: " + newText);OnTextUpdated.Invoke(newText);}
}public class ObserverUsingEvent : MonoBehaviour
{public SubjectWithEvent subject;void Start(){subject.OnTextUpdated.AddListener(OnTextUpdatedHandler);}void OnDestroy(){subject.OnTextUpdated.RemoveListener(OnTextUpdatedHandler);}void OnTextUpdatedHandler(string message){Debug.Log("Received text update: " + message);}
}

示例4 - 泛型观察者和可序列化的事件系统

[System.Serializable]
public class GenericEvent<T> : UnityEvent<T>
{
}public class ObservableGeneric<T> : MonoBehaviour
{public GenericEvent<T> OnStateChanged;public T State { get; private set; }public void ChangeState(T newState){State = newState;OnStateChanged?.Invoke(newState);}
}public class ObserverForGeneric<T> : MonoBehaviour
{public ObservableGeneric<T> observable;public void Awake(){observable.OnStateChanged.AddListener(StateChangedHandler);}public void OnDestroy(){observable.OnStateChanged.RemoveListener(StateChangedHandler);}void StateChangedHandler(T newState){Debug.Log($"New state received: {newState}");}
}// 使用示例
public class ExampleUsage : MonoBehaviour
{public ObservableGeneric<int> healthObservable;public ObserverForGeneric<int> healthObserver;void Start(){healthObserver.observable = healthObservable;}
}

示例5 - 使用C#委托简化版

public class SimpleObservable
{public delegate void MessageEventHandler(string message);public event MessageEventHandler OnMessageEvent;public void SendMessage(string message){OnMessageEvent?.Invoke(message);}
}public class SimpleObserver : MonoBehaviour
{public SimpleObservable observable;void Start(){observable.OnMessageEvent += HandleMessageEvent;}void OnDestroy(){observable.OnMessageEvent -= HandleMessageEvent;}void HandleMessageEvent(string message){Debug.Log("Received message: " + message);}
}// 使用示例
public class SimpleExample : MonoBehaviour
{public SimpleObservable messageSource;public SimpleObserver messageRecipient;void Start(){messageRecipient.observable = messageSource;messageSource.SendMessage("Hello from the Observable");}
}