Unity 建造者模式（实例详解）

文章目录

- - 说明
  - 实例1：构建游戏角色
  - 实例2：构建游戏场景
  - 实例3：构建UI界面

说明

在Unity中，建造者模式（Builder Pattern）是一种创建型设计模式，它通过分离对象构建过程的复杂性，允许您以更灵活和可扩展的方式创建不同变体的对象。这种模式尤其适用于需要构造具有多个可选或必须组件的对象，并且希望客户端代码无需了解内部构造细节的情况下。

以下是Unity中使用建造者模式的三个实例：

实例1：构建游戏角色

假设我们正在开发一个角色扮演游戏，游戏角色由多种部件组成，如身体、头部、装备、技能等。我们可以为游戏角色创建一个Builder类来逐个添加这些部分：

// 角色接口
public interface ICharacterBuilder
{
    void SetBody(BodyPart body);
    void SetHead(HeadPart head);
    void SetEquipment(Equipment equipment);
    void SetSkills(List<Skill> skills);

    // 构建完整角色的方法
    Character Build();
}

// 具体的建造者实现
public class PlayerCharacterBuilder : ICharacterBuilder
{
    private BodyPart _body;
    private HeadPart _head;
    private Equipment _equipment;
    private List<Skill> _skills;

    public void SetBody(BodyPart body) => _body = body;
    public void SetHead(HeadPart head) => _head = head;
    public void SetEquipment(Equipment equipment) => _equipment = equipment;
    public void SetSkills(List<Skill> skills) => _skills = skills;

    public Character Build()
    {
        return new Character(_body, _head, _equipment, _skills);
    }
}

// 客户端代码调用
var builder = new PlayerCharacterBuilder();
builder.SetBody(someBody);
builder.SetHead(someHead);
builder.SetEquipment(someEquipment);
builder.SetSkills(characterSkills);
var player = builder.Build();

实例2：构建游戏场景

在Unity中，构建复杂的场景也是一个可以利用建造者模式的过程。例如，一个SceneBuilder类可以用来逐步地添加游戏对象、灯光、摄像机和其他组件到场景中：

// 场景构建器接口
public interface ISceneBuilder
{
    void AddGameObject(GameObject go);
    void SetMainCamera(Camera camera);
    void AddLight(Light light);
    Scene BuildScene();
}

// 具体场景构建器实现
public class LevelOneSceneBuilder : ISceneBuilder
{
    private List<GameObject> _gameObjects = new List<GameObject>();
    private Camera _mainCamera;
    private List<Light> _lights = new List<Light>();

    public void AddGameObject(GameObject go) => _gameObjects.Add(go);
    public void SetMainCamera(Camera camera) => _mainCamera = camera;
    public void AddLight(Light light) => _lights.Add(light);

    public Scene BuildScene()
    {
        var scene = new Scene(); // Unity 不直接支持这样创建场景，此处仅做示意
        foreach (var go in _gameObjects)
            SceneManager.MoveGameObjectToScene(go, scene);
        _mainCamera.gameObject.SetActive(true); // 设置主摄像机
        foreach (var light in _lights)
            SceneManager.MoveGameObjectToScene(light.gameObject, scene);
        return scene; // 返回构建完成的场景（实际应用中会有所不同）
    }
}

// 使用示例
var levelBuilder = new LevelOneSceneBuilder();
levelBuilder.AddGameObject(playerGO);
levelBuilder.AddGameObject-enemyGO);
levelBuilder.SetMainCamera(mainCam);
levelBuilder.AddLight(sceneLight);
var scene = levelBuilder.BuildScene();

实例3：构建UI界面

在Unity UI系统中，构建用户界面可能涉及到很多不同的元素，如面板、按钮、文本标签等。通过Builder Pattern，可以简化这个过程：

// UI构建器接口
public interface IUIMenuBuilder
{
    void AddButton(string text, Action onClick);
    void AddLabel(string labelText);
    void AddSlider(float min, float max, float value);
    UnityEngine.UI.Canvas BuildCanvas();
}

// 具体UI构建器实现
public class MainMenuBuilder : IUIMenuBuilder
{
    private CanvasGroup canvasGroup;
    private RectTransform container;
    private List<UnityEngine.UI.Button> buttons = new List<UnityEngine.UI.Button>();
    private List<UnityEngine.UI.Text> labels = new List<UnityEngine.UI.Text>();
    private List<UnityEngine.UI.Slider> sliders = new List<UnityEngine.UI.Slider>();

    public MainMenuBuilder(Canvas canvas)
    {
        canvasGroup = canvas.GetComponent<CanvasGroup>();
        container = new GameObject("Menu Container").AddComponent<RectTransform>();
        container.SetParent(canvas.transform);
    }

    public void AddButton(string text, Action onClick)
    {
        var button = Instantiate(buttonPrefab, container);
        button.GetComponentInChildren<Text>().text = text;
        button.onClick.AddListener(() => onClick());
        buttons.Add(button);
    }

    public void AddLabel(string labelText)
    {
        var label = Instantiate(labelPrefab, container);
        label.text = labelText;
        labels.Add(label);
    }

    public void AddSlider(float min, float max, float value)
    {
        var slider = Instantiate(sliderPrefab, container);
        slider.minValue = min;
        slider.maxValue = max;
        slider.value = value;
        sliders.Add(slider);
    }

    public UnityEngine.UI.Canvas BuildCanvas()
    {
        return canvasGroup.canvas;
    }
}

// 使用示例
var menuBuilder = new MainMenuBuilder(mainCanvas);
menuBuilder.AddButton("Start Game", StartGame);
menuBuilder.AddLabel("Welcome to the game!");
menuBuilder.AddSlider(0f, 100f, 50f);
var builtCanvas = menuBuilder.BuildCanvas();