工厂模式分为三种：
1. 简单工厂
特点：一个工厂类根据传入的参量决定创建出那一种产品类的实例，如果想要增加一个产品，需要修改工厂类，该设计破坏了开闭原则。
public interface Fruit {
}
public class Apple implements Fruit {
}
public class Orange implements Fruit {
}
public class SimpleFactory {
public static Fruit createFruit(String name){
if("apple".equals(name)){
return new Apple();
}else if("orange".equals(name)){
return new Orange();
}else{
throw new RuntimeException("unknown fruit name");
}
}
}
public class T {
public static void main(String[] args) {
Fruit apple = SimpleFactory.createFruit("apple");
}
}
2. 工厂方法
特点：定义一个用于创建产品的接口，由子类决定生产什么产品。每个产品都对应了一个创建者，每个创建者独立负责创建对应的产品对象，非常符合单一职责原则。但是每增加一个产品都需要增加一个对应的工厂实现，增加了系统的复杂性
public interface Fruit {
}
public class Apple implements Fruit {
}
public class Orange implements Fruit {
}
public interface FruitFactory {
Fruit createFruit();
}
public class AppleFactory implements FruitFactory {
@Override
public Fruit createFruit() {
return new Apple();
}
}
public class OrangeFactory implements FruitFactory {
@Override
public Fruit createFruit() {
return new Orange();
}
}
public class T {
public static void main(String[] args) {
FruitFactory appleFactory = new AppleFactory();
Fruit apple = appleFactory.createFruit();
FruitFactory orangeFactory = new OrangeFactory();
Fruit orange = orangeFactory.createFruit();
}
}
3. 抽象工厂
特点：提供一个创建产品族的接口，其每个子类可以生产一系列相关的产品。创建相关或依赖对象的家族，而无需明确指定具体类，但是在新增一个产品时，需要修改工厂接口及其子类，破坏了开闭原则
public interface Staple {
}
public class Flour implements Staple {
}
public class Rice implements Staple {
}
public interface Dish {
}
public class Cabbage implements Dish {
}
public class Radish implements Dish{
}
public interface FoodFactory {
Staple createStaple();
Dish createDish();
}
public class NorthFood implements FoodFactory {
@Override
public Staple createStaple() {
return new Flour();
}
@Override
public Dish createDish() {
return new Radish();
}
}
public class SouthFood implements FoodFactory {
@Override
public Staple createStaple() {
return new Rice();
}
@Override
public Dish createDish() {
return new Cabbage();
}
}
public class T {
public static void main(String[] args) {
FoodFactory southFoodFactory = new SouthFood();
Dish cabbage = southFoodFactory.createDish();
Staple rice = southFoodFactory.createStaple();
FoodFactory norFoodFactory = new NorthFood();
Dish rasidh = southFoodFactory.createDish();
Staple flour = southFoodFactory.createStaple();
}
}
