设计模式 - 工厂模式

简单工厂模式

基本介绍:

简单工厂模式是属于创建型模式，是工厂模式的一种。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
简单工厂模式：定义了一个创建对象的类，由这个类来封装实例化对象的行为
在软件开发中，当我们会用到大量的创建某种、某类或者某批对象时，就会使用到工厂模式

定义抽象类:

public abstract class Pizza {protected String name;public abstract void prepare();public void bake() {System.out.println(name + " baking;");}public void cut() {System.out.println(name + " cutting;");}public void box() {System.out.println(name + " boxing;");}public void setName(String name) {this.name = name;}
}

定义 Pizza 继承类:

public class CheesePizza extends Pizza{@Overridepublic void prepare() {setName("奶酪pizza");System.out.println(name + " preparing;");}
}public class GreekPizza extends Pizza {@Overridepublic void prepare() {setName("GreekPizza");System.out.println(name + " preparing;");}
}public class PepperPizza extends Pizza {@Overridepublic void prepare() {setName("PepperPizza");System.out.println(name + " preparing;");}
}

定义工厂类:

public class SimplePizzaFactory {public Pizza createPizza(String type){System.out.println(" 使用简单工厂模式");Pizza pizza = null;if (type.equals("cheese")) {pizza = new CheesePizza();}else if(type.equals("greek")){pizza = new GreekPizza();} else if (type.equals("pepper")) {pizza = new PepperPizza();}return pizza;}
}

使用:

public class OrderPizza {SimplePizzaFactory simpleFactory;Pizza pizza;String orderType;public OrderPizza(SimplePizzaFactory simpleFactory, String orderType) {this.orderType = orderType;this.setFactory(simpleFactory);}public void setFactory(SimplePizzaFactory simpleFactory) {this.simpleFactory = simpleFactory;pizza = simpleFactory.createPizza(orderType);pizza.prepare();pizza.bake();pizza.cut();pizza.box();}public static void main(String[] args) {SimplePizzaFactory simpleFactory = new SimplePizzaFactory();OrderPizza orderPizza = new OrderPizza(simpleFactory, "greek");}
}

工厂方法模式

基本介绍:

定义了一个创建对象的抽象方法，由子类决定要实例化的类。工厂方法模式将对象的实例化推迟到子类

定义抽象方法，让各个工厂子类自己实现:

public abstract class OrderPizza {Pizza pizza;public OrderPizza(String orderType) {pizza = createPizza(orderType);//抽象方法，由工厂子类完成//输出 pizza 制作过程pizza.prepare();pizza.bake();pizza.cut();pizza.box();}public OrderPizza() {}//定义一个抽象方法，createPizza，让各个工厂子类自己实现abstract Pizza createPizza(String orderlype);public static void main(String[] args) {OrderPizza pizza = new BJOrderPizza("cheese");}
}

子类实现一:

public class BJCheesePizza extends Pizza {@Overridepublic void prepare() {setName("BJ奶酪pizza");System.out.println(name + " preparing;");}
}public class BJPepperPizza extends Pizza {@Overridepublic void prepare() {setName("BJPepperPizza");System.out.println(name + " preparing;");}
}public class BJOrderPizza extends OrderPizza{public BJOrderPizza(String orderType) {super(orderType);}@OverridePizza createPizza(String orderType) {Pizza pizza = null;if(orderType.equals("cheese")) {pizza = new BJCheesePizza();} else if(orderType.equals("pepper")) {pizza = new BJPepperPizza();}return pizza;}
}

子类实现二:

public class SHCheesePizza extends Pizza {@Overridepublic void prepare() {setName("SH奶酪pizza");System.out.println(name + " preparing;");}
}public class SHPepperPizza extends Pizza {@Overridepublic void prepare() {setName("SHPepperPizza");System.out.println(name + " preparing;");}
}public class SHOrderPizza extends OrderPizza{public SHOrderPizza(String orderType) {super(orderType);}@OverridePizza createPizza(String orderType) {Pizza pizza = null;if(orderType.equals("cheese")) {pizza = new SHCheesePizza();} else if(orderType.equals("pepper")) {pizza = new SHPepperPizza();}return pizza;}
}

抽象工厂模式

基本介绍:

抽象工厂模式：定义了一个interface用于创建相关或有依赖关系的对象簇，而无需指明具体的类
抽象工厂模式可以将简单工厂模式和工厂方法模式进行整合
从设计层面看，抽象工厂模式就是对简单工厂模式的改进
将工厂抽象成两层，AbsFactory(抽象工厂) 和具体实现的工厂子类。程序员可以根据创建对象类型使用对应的工厂子类。这样将单个的简单工厂类变成了工厂簇，更利于代码的维护和扩展

抽象工厂的抽象层:

/*** 声明AbsFactory接口*/
public interface AbsFactory {//让不同的工厂类来实现createPizza方法public Pizza createPizza(String type);
}

具体实现一:

public class BJCheesePizza extends Pizza {@Overridepublic void prepare() {setName("BJ奶酪pizza");System.out.println(name + " preparing;");}
}public class BJPepperPizza extends Pizza {@Overridepublic void prepare() {setName("BJPepperPizza");System.out.println(name + " preparing;");}
}public class BJFactory implements AbsFactory {@Overridepublic Pizza createPizza(String orderType) {Pizza pizza = null;if(orderType.equals("cheese")) {pizza = new BJCheesePizza();} else if(orderType.equals("pepper")) {pizza = new BJPepperPizza();}return pizza;}
}

具体实现二:

public class SHCheesePizza extends Pizza {@Overridepublic void prepare() {setName("SH奶酪pizza");System.out.println(name + " preparing;");}
}public class SHPepperPizza extends Pizza {@Overridepublic void prepare() {setName("SHPepperPizza");System.out.println(name + " preparing;");}
}public class SHFactory implements AbsFactory {@Overridepublic Pizza createPizza(String orderType) {Pizza pizza = null;if(orderType.equals("cheese")) {pizza = new SHCheesePizza();} else if(orderType.equals("pepper")) {pizza = new SHPepperPizza();}return pizza;}
}

执行类:

public class OrderPizza {AbsFactory factory;String orderType;// 构造器public OrderPizza(AbsFactory factory, String orderType) {this.orderType = orderType;setFactory(factory);}public void setFactory(AbsFactory factory){Pizza pizza = null;this.factory = factory;pizza = factory.createPizza(orderType);//输出 pizza 制作过程pizza.prepare();pizza.bake();pizza.cut();pizza.box();}public static void main(String[] args) {BJFactory factory = new BJFactory();OrderPizza orderPizza = new OrderPizza(factory, "greek");}
}