略懂略懂的IoC與DI

略懂略懂的IoC與DI

簡單來說,就是用來減少class間依賴的方法

先來說說遇到的狀況,
實作遊戲時,
將UI在class終實體化



部分程式碼

...
void Start () {
    GameControllOriginal o = new GameControllOriginal();
    o.RunGame();
}
...

class 長這樣

class GameUI
{
    public void GameUIInit() {
        Debug.Log("UI Init!");
    }

    public void ShowSomething() {
        Debug.Log("UI ShowSomething!");
    }

    public void UpdateUI() {
        Debug.Log("UI UpdateUI!");
    }
}

class GameControllOriginal
{
    GameUIBase UI = null;

    public GameControllOriginal() //我們在class new 出了 GameUI
    {
        GameUI ui = new GameUI();
        UI = ui;
    }
    public void RunGame()
    {
        Debug.Log("HiHi!");
        UI.ShowSomething();
        UI.UpdateUI();
    }
}

這時GameControllOriginal對GameUI 產生了依賴,
當今天有新的GameUI2時勢必得修改GameControllOriginal,
因此,
我們使用DI解決這層問題!

依賴注入 DI(Dependency Injection)
在外面生成好class 再注入

部分程式碼

...
void Start () {
    GameUI ui = new GameUI();
    GameControllOriginal o = new GameControllOriginal(ui);
    o.RunGame();
}
...

class 修改成這樣

class GameControllOriginal
{
    GameUIBase UI = null;
    public GameControllOriginal(GameUI ui)   //相依性移出
    {
        UI = ui;
    }
    public void RunGame()
    {
        Debug.Log("HiHi!");
        UI.ShowSomething();
        UI.UpdateUI();
    }
}

控制反轉 IOC(Inversion of Control)
將依賴拔出來的這個過程,
就是控制反轉

假如今天的需求為:
希望將UI獨立出來,
即使沒有UI流程狀況下邏輯部分還是可以運作的

部分程式碼

...
void Start () {
    bool NeedUI = false;
    GameUI gameUI = null;
    if (NeedUI)
        gameUI = new GameUI();
    else
        gameUI = new GameUIBase();
    GameControll controll = new GameControll(gameUI);
    controll.RunGame();
}
...

class 長這樣

class GameUIBase
{
    public GameUIBase() { }
    public virtual void GameUIInit(){}
    public virtual void ShowSomething(){}
    public virtual void UpdateUI() {}
}

class GameUI : GameUIBase
{
    public override void GameUIInit() {
        Debug.Log("UI Init!");
    }
    public override void ShowSomething() {
        Debug.Log("UI ShowSomething!");
    }
    public override void UpdateUI() {
        Debug.Log("UI UpdateUI!");
    }
}

class GameControll
{
    GameUIBase UI =null;

    public GameControll(GameUIBase ui)
    {
        UI = ui;
    }

    public void RunGame()
    {
        Debug.Log("HiHi!");
        UI.ShowSomething();
        UI.UpdateUI();
    }
}

當不需要UI時輸出:
HiHi!

當需要UI時輸出:
HiHi!
UI ShowSomething!
UI UpdateUI!

心得:
IoC與DI,
將變動大的部分都抽像化,
抽出class,
再依需求實作相對應的class並注入,
使開發更彈性~~