简单工厂模式

简单工厂模式是由一个工厂对象决定创建出哪一种产品类的实例。简单工厂模式是工厂模式家族中最简单实用的模式，可以理解为是不同工厂模式的一个特殊实现。
简单工厂模式的实质是由一个工厂类根据传入的参数，动态决定应该创建哪一个产品类（这些产品类继承自一个父类或接口）的实例。

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JS

JavaScript中没有Interface关键字，但可以用它的特性去模仿，
模拟Interface的实现有如下三种方法：
1.注释法
2.属性检查法
3.鸭式辨型法

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这里采用鸭式辨型法

Interface

var Interface = function(name, methods){    if (arguments.length != 2) {        throw new Error("Interface constructor called with " + arguments.length +        "arguments,but expected exactyl 2.")    }    this.name = name;    this.methods = [];    for (var i = 0, len = methods.length; i < len; i++) {        if (typeof methods[i] !== "string") {            throw new Error("Interface constructor expects methods names to bo " +            "passed in asastring.");        }        this.methods.push(methods[i]);    }}Interface.ensureImplements = function(object){        if (arguments.length < 2) {                throw new Error("Function Interface.ensureImplements called with " + arguments.length +                "arguments,but expected at least 2.");        }        for (var i = 1, len = arguments.length; i < len; i++) {                var inter_face = arguments[i];                if (inter_face.constructor !== Interface) {                        throw new Error("Function Interface.ensureImplementsexpects arguments " +                        "two and above to be instances of Interface.");                }                for (var j = 0, methodsLen = inter_face.methods.length; j < methodsLen; j++) {                        var method = inter_face.methods[j];                        if (!object[method] || typeof object[method] !== 'function') {                                throw new Error("Function Interface.ensureImplements: object " +                                "does not implements the " +                                inter_face.name +                                "interface.Method " +                                method +                                "was not found.");                        }                }        }}

Creator

var Creator = function(){};Creator.prototype ={    Product : function(model){        var concreteProduct = null;        switch(model){            case 'A':                concreteProduct = new ConcreteProductA();                break;            case 'B':                concreteProduct = new ConcreteProductB();                break;            case 'C':                concreteProduct = new ConcreteProductC();                break;        };        Interface.ensureImplements(concreteProduct,Product);        return concreteProduct;    }};

Product

var Product = new Interface("ConcreteProduct",['MethodA','MethodB','MethodC','MethodD']);

ConcreteProduct

var ConcreteProductA =function(){};ConcreteProductA.prototype= {    MethodA:function(){alert("ConcreteProductA MethodA");},    MethodB:function(){...},    MethodC:function(){...},    MethodD:function(){...}};           .           .           .

test

var obj = new Creator();obj.Product("A").MethodA();

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Java

Creator

public class Creator {   public Product getProduct(String model) {       switch(model)       {       case "A" : return new ConcreteProductA();       case "B" : return new ConcreteProductB();       case "C" : return new ConcreteProductC();       default:return null;       }   }}

Product

public interface Product {    void MethodA();    void MethodB();    void MethodC();}

ConcreteProduct

public class ConcreteProductA implements Product{    public void MethodA() {        System.out.println("ConcreteProductA MethodA");    }    public void MethodB() {        System.out.println("ConcreteProductB MethodB");    }    public void MethodC() {        System.out.println("ConcreteProductC MethodC");    }}               .               .               .

test

public class test {    public static void main(String[] args){    Creator creator = new Creator();    creator.getProduct("A").MethodA();    }}

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C艹

Creator

class Creator{public:    Product* getProduct(char model)    {        switch (model)        {        case 'A':            return new ConcreteProductA();            break;        case 'B':            return new ConcreteProductB();            break;        default:            break;        }    }};

Product

class Product{public: virtual void MethodA() = 0;public: virtual void MethodB() = 0;public: virtual void MethodC() = 0;};

ConcreteProduct

class ConcreteProductA :public Product{public:    virtual void MethodA()    {        cout << "ConcreteProductA MethodA" << endl;    }    virtual void MethodB()    {        cout << "ConcreteProductA MethodB" << endl;    }    virtual void MethodC()    {        cout << "ConcreteProductA MethodC" << endl;    }};              。              。              。

test

int main(int argc, char* argv[]){    Creator creator;    Product* Product;    Product = creator.getProduct('A');    Product->MethodA();    delete Product;    system("pause");    return 0;}

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C井

Creator

 public class Creator    {        public Product getProduct(string model) {            switch (model)            {                case "A":                     return new ConcreteProductA();                case "B":                    return new ConcreteProductB();                default:                    return null;            }        }    }

Product

 public interface Product    {         void MethodA();         void MethodB();         void MethodC();    }

ConcreteProduct

class ConcreteProductA : Product    {        public void MethodA()        {            Console.WriteLine("ConcreteProductA MethodA");        }        public void MethodB()        {            Console.WriteLine("ConcreteProductA MethodB");        }        public void MethodC()        {            Console.WriteLine("ConcreteProductA MethodC");        }    }                     。                     。                     。

test

 class test    {        static void Main(string[] args)        {            Creator creator = new Creator();            creator.getProduct("A").MethodB();        }    }