最近在看《設(shè)計模式與游戲完美開發(fā)》，文章將記錄一些要點和一些設(shè)計模式實現(xiàn)

GoF定義的23種設(shè)計模式及應(yīng)用場景

• 系統(tǒng)設(shè)計可以采用的設(shè)計模式：單例、狀態(tài)（場景切換）、外觀（保證高內(nèi)聚）、中介者（保證低解耦）
• 角色設(shè)計可以采用的設(shè)計模式：橋接（武器、技能）、策略（屬性計算）、模板方法（重復(fù)流程）、狀態(tài)（AI）
• 對象管理可以采用的設(shè)計模式：工廠（角色產(chǎn)生）、建造者（生產(chǎn)流程與功能表現(xiàn)分離）、享元（子彈、特效）
• 邏輯設(shè)計可以采用的設(shè)計模式：命令（撤銷回退）、責任鏈（關(guān)卡）
• 輔助功能可以采用的設(shè)計模式：組合（UI、紅點）、觀察者（好友、成就）、備忘錄（存檔）、訪問者（管理某一類對象）
• 游戲優(yōu)化可以采用的設(shè)計模式：裝飾、適配器、代理
• 其他模式：迭代器、原型、解釋器、抽象工廠

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中介者模式

關(guān)于中介者模式，我們想象在一家互聯(lián)網(wǎng)公司，有多個Colleague（同事），Colleague（同事）之間需要合作開發(fā)，不管是采用哪種版本控制軟件，都可以抽象為一個Mediator（中介者）。而每個Colleague（同事）需要有版本控制的權(quán)限，即Mediator引用，而ConcreteMediator（具體中介者）則為ConcreteColleague（具體同事）提供服務(wù)。

Mediator.cs

public abstract class Mediator {public abstract void SendMessage(Colleague theColleage, string message); }

ConcreateMediator.cs

public class ConcreateMediator : Mediator {ConcreateColleague1 m_Colleague1 = null;ConcreateColleague2 m_Colleague2 = null;public void SetColleage1(ConcreateColleague1 theColleague){m_Colleague1 = theColleague;}public void SetColleage2(ConcreateColleague2 theColleague){m_Colleague2 = theColleague;}public override void SendMessage(Colleague theColleague, string message){if (theColleague == m_Colleague1){m_Colleague2.Request(message);} else if (theColleague == m_Colleague2){m_Colleague1.Request(message);}} }

Colleage.cs

public abstract class Colleague {protected Mediator m_Mediator = null;public Colleague(Mediator mediator){m_Mediator = mediator;}public abstract void Request(string message); }

ConcreateColleage1.cs、ConcreateColleage2.cs

using UnityEngine; public class ConcreateColleague1 : Colleague {public ConcreateColleague1(Mediator mediator) : base(mediator){}public void Action(){m_Mediator.SendMessage(this, "Concreate1執(zhí)行");}public override void Request(string message){Debug.Log("C2已接收：" + message);} } using UnityEngine; public class ConcreateColleague2 : Colleague {public ConcreateColleague2(Mediator mediator) : base(mediator){}public void Action(){m_Mediator.SendMessage(this, "Concreate2執(zhí)行");}public override void Request(string message){Debug.Log("C2已接收：" + message);} }

Test.cs

using UnityEngine;public class Test : MonoBehaviour {void Start(){// 定義具體中介者、具體同事ConcreateMediator pMediator = new ConcreateMediator();ConcreateColleague1 pColleage1 = new ConcreateColleague1(pMediator);ConcreateColleague2 pColleage2 = new ConcreateColleague2(pMediator);// 添加同事pMediator.SetColleage1(pColleage1);pMediator.SetColleage2(pColleage2);// 同事執(zhí)行行為，中介者負責派發(fā)消息pColleage1.Action();pColleage2.Action();}void Update(){} }

tips：有些情況下，Mediator會同時采用單例模式實現(xiàn)，在這種情況下，盡量避免從Mediator派生ConcreateMediator，這是因為當ConcreateMediator作為單例使用時，會因為單例只會存在唯一示例，當父類有多個派生類時會有“白馬非馬”的邏輯詭辯。同時為了遵循開閉原則，也要盡量依賴“接口”，而非依賴“實現(xiàn)”。

里氏替換原則有至少以下兩種含義：
里氏替換原則是針對繼承而言的，如果繼承是為了實現(xiàn)代碼重用，那么共享的父類方法就應(yīng)該保持不變，不能被子類重新定義。 如果繼承的目的是為了多態(tài)，而多態(tài)的前提就是子類覆蓋并重新定義父類的方法，應(yīng)該將父類定義為抽象類。不符合LSP的最常見的情況是，父類和子類都是可實例化的非抽象類，且父類的方法被子類重新定義，這一類的實現(xiàn)繼承會造成父類和子類間的強耦合，也就是實際上并不相關(guān)的屬性和方法牽強附會在一起，不利于程序擴展和維護。

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工廠模式

工廠模式是最簡單的一種設(shè)計模式，由ConcreteCreate(具體工廠)產(chǎn)生ConcreateProduct（具體產(chǎn)品）
Creator.cs

public abstract class Creator {public abstract Product FactoryMethod(); }

ConcreateCreatorProductA.cs

using UnityEngine;public class ConcreateCreatorProductA : Creator {public ConcreateCreatorProductA(){Debug.Log("產(chǎn)生工廠A");}public override Product FactoryMethod(){return new ConcreateProductA();} }

Product.cs

public abstract class Product { }

ConcreateProductA

using UnityEngine;public class ConcreateProductA : Product {public ConcreateProductA(){Debug.Log("生產(chǎn)A");} }

tips：通過不同子類工廠產(chǎn)生不同品類的產(chǎn)品，當產(chǎn)品種類過多時，會導致“工廠子類暴增”。這時候可以配合FactoryMethod傳參實現(xiàn)工廠模式

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建造者模式

對于一個工廠來說，一條流水線應(yīng)該可以生產(chǎn)多種產(chǎn)品嗎，即生產(chǎn)流程與產(chǎn)品裝配是可以解耦的。由Director（建造者指示者）對產(chǎn)品生產(chǎn)流程進行管控，而Builder（建造者）有很多ConcerteBuilder（具體建造者）則負責不同功能的裝配。

Director.cs

public class Director {public Product m_Product;public Director() { }public void Construct(Builder theBuilder){m_Product = new Product();theBuilder.BuilderPart1(m_Product);theBuilder.BuilderPart2(m_Product);}public Product GetResult(){return m_Product;} }

Builder.cs

public abstract class Builder {public abstract void BuilderPart1(Product theProduct);public abstract void BuilderPart2(Product theProduct); }

ConcreateBuilderA.cs

public class ConcreateBuilderA : Builder {public override void BuilderPart1(Product theProduct){theProduct.AddPart("產(chǎn)品A工人:生產(chǎn)部件1");}public override void BuilderPart2(Product theProduct){theProduct.AddPart("產(chǎn)品A工人:生產(chǎn)部件2");} } using UnityEngine; using System.Collections;public class ConcreateBuilderB : Builder {public override void BuilderPart1(Product theProduct){theProduct.AddPart("產(chǎn)品B工人:生產(chǎn)部件1");}public override void BuilderPart2(Product theProduct){theProduct.AddPart("產(chǎn)品B工人:生產(chǎn)部件2");} }

Product.cs

using UnityEngine; using System.Collections.Generic;public class Product {private List<string> m_Part = new List<string>();public Product() { }public void AddPart(string v){m_Part.Add(v);}public void ShowProduct(){foreach(var part in m_Part){Debug.Log(part);}} }

Test.cs

using UnityEngine;public class Test : MonoBehaviour {Director director = new Director();Product theProduct = null;void Start(){director.Construct(new ConcreateBuilderA());theProduct = director.GetResult();theProduct.ShowProduct();director.Construct(new ConcreateBuilderB());theProduct = director.GetResult();theProduct.ShowProduct();} }

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享元模式

書中描述的案例，個人以為不適合理解，故此處暫留

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組合模式

“將對象以樹狀結(jié)構(gòu)進行組合，用以表現(xiàn)部分與整體的層次關(guān)系”，UI的層次結(jié)構(gòu)正好適合使用這種設(shè)計模式。

Component（組件界面）用來定義樹形結(jié)構(gòu)，以及每個結(jié)點都能使用的操作，Composite（組合結(jié)點，即根結(jié)點），實現(xiàn)Component定義的各個方法，Leaf（葉結(jié)點，終端結(jié)點）
IComponent.cs

using UnityEngine;public abstract class IComponent {protected string m_Value;public abstract void Operation();public virtual void Add(IComponent theComponent){Debug.Log("子類未實現(xiàn)");}public virtual void Remove(IComponent theComponent){Debug.Log("子類未實現(xiàn)");}public virtual IComponent GetChild(int index){Debug.Log("子類未實現(xiàn)");return null;} }

Composite.cs

using UnityEngine; using System.Collections.Generic;public class Composite : IComponent {List<IComponent> m_Childs = new List<IComponent>();public Composite(string value){m_Value = value;}public override void Add(IComponent theComponent){m_Childs.Add(theComponent);}public override void Remove(IComponent theComponent){m_Childs.Remove(theComponent);}public override IComponent GetChild(int index){return m_Childs[index];}public override void Operation(){Debug.Log("根節(jié)點執(zhí)行" + m_Value);foreach (IComponent theComponent in m_Childs){theComponent.Operation();}} }

Leaf.cs

using UnityEngine;public class Leaf : IComponent {public Leaf(string value){m_Value = value;}public override void Operation(){Debug.Log("葉節(jié)點執(zhí)行:" + m_Value);} }

test.cs

using UnityEngine;public class Test2 : MonoBehaviour {IComponent theRoot;void Start(){theRoot = new Composite("Root");theRoot.Add(new Leaf("Leaf1"));theRoot.Add(new Leaf("Leaf2"));IComponent theChild1 = new Composite("Child1");theChild1.Add(new Leaf("child1.Leaf1"));theChild1.Add(new Leaf("child1.Leaf2"));theRoot.Add(theChild1);IComponent theChild2 = new Composite("Child1");theChild2.Add(new Leaf("child2.Leaf1"));theChild2.Add(new Leaf("child2.Leaf2"));theRoot.Add(theChild2);theRoot.Operation();} }

tips:GameObject.Find()會遍歷所有場景中的對象，而且在Unity中存在重名的問題，會產(chǎn)生性能問題。可以通過自己實現(xiàn)Find，保證只在指定的Canvas下查找
UI的功能在場景初始化時決定，保證UI邏輯與表現(xiàn)分離

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責任鏈模式

責任鏈可以理解為數(shù)據(jù)結(jié)構(gòu)的鏈表，每個Handler都有下一個Handler的引用。在關(guān)卡系統(tǒng)的設(shè)計上，很多項目會采用CreateStage（創(chuàng)建關(guān)卡）、CheckNextStage（檢查進入下一關(guān)）方法來對場景進行操作，而采用責任鏈模式，則可以使用Handler（關(guān)卡對象）替代，通過類化關(guān)卡數(shù)據(jù)、通關(guān)條件能夠提高關(guān)卡系統(tǒng)的靈活度。
Handler.cs

public abstract class Handler {protected Handler m_NextHandle = null;public Handler(Handler theNextHandle){m_NextHandle = theNextHandle;}public virtual void HandleRequest(int cost){if (m_NextHandle != null){m_NextHandle.HandleRequest(cost);}} }

ConcreateHandle1.cs

using UnityEngine;public class ConcreateHandle1 : Handler {public int m_CostCheck = 10;public ConcreateHandle1(Handler theNextHandle) : base(theNextHandle) { }public override void HandleRequest(int cost){if (cost < m_CostCheck){Debug.Log("ConcreateHandle2核準");} else{base.HandleRequest(cost);}} }

ConcreateHandle2.cs

using UnityEngine;public class ConcreateHandle2 : Handler {public int m_CostCheck = 20;public ConcreateHandle2(Handler theNextHandle) : base(theNextHandle) { }public override void HandleRequest(int cost){if (cost <= m_CostCheck){Debug.Log("ConcreateHandle2核準");}else{base.HandleRequest(cost);}} }

Test.cs

using UnityEngine; using System.Collections;public class Test : MonoBehaviour {void Start(){ConcreateHandle2 theHandle2 = new ConcreateHandle2(null);ConcreateHandle1 theHandle1 = new ConcreateHandle1(theHandle2);theHandle1.HandleRequest(5);theHandle1.HandleRequest(20);} }

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觀察者模式

對于發(fā)布-訂閱關(guān)系來說，一個Subject可以對應(yīng)多個Observer，Subject維護觀察者列表，并提供Notify()通知功能；Observer提供Update()方法，在Subject通知更新時調(diào)用。
Subject.cs

using System.Collections.Generic;public abstract class Subject {List<Observer> m_Observer = new List<Observer>();public void Attach(Observer theObserver){m_Observer.Add(theObserver);}public void Detach(Observer theObserver){m_Observer.Remove(theObserver);}public void Notify(){// 通知所有觀察者foreach (Observer observer in m_Observer){observer.Update();}} }

ConcreateSubject.cs

using UnityEngine; using System.Collections;public class ConcreateSubject : Subject {string m_SubjectState;public void SetState(string state){m_SubjectState = state;Notify();}public string GetState(){return m_SubjectState;} }

Observer.cs

using UnityEngine; using System.Collections;public abstract class Observer {public abstract void Update(); }

ConcreateObserver.cs

using UnityEngine;public class ConcreateObserver : Observer {string m_ObjectState;ConcreateSubject m_Subject = null;public ConcreateObserver(ConcreateSubject subject){m_Subject = subject;}public override void Update(){Debug.Log("ConcreteObserver.Update");Debug.Log("ConcreateObserver1:Subject" + m_ObjectState);} }

Test.cs

using UnityEngine; using System.Collections;public class Test : MonoBehaviour {ConcreateSubject theSubject = null;ConcreateObserver theObserver = null;// Use this for initializationvoid Start(){theSubject = new ConcreateSubject();theObserver = new ConcreateObserver(theSubject);theSubject.Attach(theObserver1); // 觀察者參與訂閱theSubject.SetState("Subject狀態(tài)1"); // 主題修改狀態(tài)，并通知theObserver1.ShowState(); // 觀察者接收通知并執(zhí)行Update()操作} }

備忘錄模式

在不違反封裝的原則下，獲取一個對象的內(nèi)部狀態(tài)并保留在外部。當我們想辦法去獲取游戲系統(tǒng)的數(shù)據(jù)時，現(xiàn)有系統(tǒng)難免被改動，而如果由游戲系統(tǒng)主動提供數(shù)據(jù)，則可以保證系統(tǒng)的封裝性，這也是備忘錄模式的精髓。Originator（記錄擁有者）會自動產(chǎn)出需要保存的記錄Memento（記錄保存者，我稱之為記憶體），由Caretaker（記錄看守者）維護多個Memento。

Originator.cs

using UnityEngine;public class Originator {string m_State;public void SetInfo(string state){m_State = state;}public void ShowInfo(){Debug.Log("Originator State" + m_State);}public Memento CreateMemento(){Memento newMemento = new Memento();newMemento.SetState(m_State);return newMemento;}public void SetMemento(Memento m){m_State = m.GetState();} }

Memento.cs

public class Memento {string m_State;public string GetState(){return m_State;}public void SetState(string state){m_State = state;} }

Caretaker.cs

using System.Collections.Generic;public class Caretaker {Dictionary<string, Memento> m_Mementos = new Dictionary<string, Memento>();public void AddMemento(string version, Memento theMemento){if (m_Mementos.ContainsKey(version) == false)m_Mementos.Add(version, theMemento);elsem_Mementos[version] = theMemento;}public Memento GetMemento(string version){if (m_Mementos.ContainsKey(version) == false)return null;return m_Mementos[version];} }

Test.cs

using System.Collections;public class Test : MonoBehaviour {void Start(){Originator theOriginator = new Originator();Caretaker theCaretaker = new Caretaker();theOriginator.SetInfo("version1");theOriginator.ShowInfo();theCaretaker.AddMemento("1", theOriginator.CreateMemento());theOriginator.SetInfo("version2");theOriginator.ShowInfo();theCaretaker.AddMemento("2", theOriginator.CreateMemento());theOriginator.SetInfo("version3");theOriginator.ShowInfo();theOriginator.SetMemento(theCaretaker.GetMemento("2"));theOriginator.ShowInfo();theOriginator.SetMemento(theCaretaker.GetMemento("1"));theOriginator.ShowInfo();} }

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