java 工厂模式（大话设计模式）

工厂方法模式：定义一个用于创建对象的接口，让子类决定实例化哪一个类。工厂方法使一个类的实例化延迟到其子类。

由于简单工厂模式不仅对扩展开放了，也对修改开放了（每添加一个类，就得去生成实例的工厂方法中增加新的分支），违背了“开放-封闭原则”。工厂方法把简单工厂的内部逻辑判断转移到了客户端代码来进行。

public interface Product
{       
}

public interface Creator
{
       public Product factory();
}

public class ConcreteProduct1 implements Product
{
       public ConcreteProduct1()
       {
              System.out.println("ConcreteProduct1被创建");
       }
}

public class ConcreteProduct2 implements Product
{
       public ConcreteProduct2()
       {
              System.out.println("ConcreteProduct2被创建");
       }
 
}

public class ConcreteCreator1 implements Creator
{
       public Product factory()
       {
              return new ConcreteProduct1();
       }
}

public class ConcreteCreator2 implements Creator
{
       public Product factory()
       {
              return new ConcreteProduct2();
       }
}
 
public class Client
{
       private static Creator creator1, creator2;
       private static Product prod1, prod2;

       public static void main(String[] args)
       {
              creator1 = new ConcreteCreator1();
              prod1 = creator1.factory();
              System.out.println("----------------------------");
              creator2 = new ConcreteCreator2();
              prod2 = creator2.factory();
       }
}

案例 学雷锋

/**
 * 工厂方法模式(Factory Method)
 * 雷锋类
 */
public class LeiFeng {

    public void sweep() {
        System.out.println("扫地");
    }

    public void wash() {
        System.out.println("洗衣");
    }

    public void buyRice() {
        System.out.println("买米");
    }

}
/**
 * 工厂方法模式(Factory Method)
 * 雷锋工厂
 */
public interface IFactory {

    LeiFeng createLeiFeng();

}

/**
 * 学雷锋的大学生工厂
 */
class UndergraduateFactory implements IFactory {

    @Override
    public LeiFeng createLeiFeng() {
        return new Undergraduate();
    }

}

/**
 * 社区志愿者工厂
 */
class VolunteerFactory implements IFactory {

    @Override
    public LeiFeng createLeiFeng() {
        return new Volunteer();
    }

}
/**
 * 工厂方法模式(Factory Method)
 * 大学生类
 */
public class Undergraduate extends LeiFeng {

    @Override
    public void sweep() {
        System.out.println("学雷锋的大学生帮忙扫地");
    }

    @Override
    public void wash() {
        System.out.println("学雷锋的大学生帮忙洗衣");
    }

    @Override
    public void buyRice() {
        System.out.println("学雷锋的大学生帮忙买米");
    }

}
/**
 * 工厂方法模式(Factory Method)
 * 社区志愿者类
 */
public class Volunteer extends LeiFeng {

    @Override
    public void sweep() {
        System.out.println("社区志愿者帮忙扫地");
    }

    @Override
    public void wash() {
        System.out.println("社区志愿者帮忙洗衣");
    }

    @Override
    public void buyRice() {
        System.out.println("社区志愿者帮忙买米");
    }

}

/**
 * 工厂方法模式(Factory Method)
 * 客户端main方法
 */
public class Client {

    public static void main(String[] args) {
        // 大学生
        IFactory undergraduateFactory = new UndergraduateFactory();
        LeiFeng student = undergraduateFactory.createLeiFeng();
        student.sweep();
        student.wash();
        student.buyRice();
        // 志愿者
        IFactory volunteerFactory = new VolunteerFactory();
        LeiFeng volunteer = volunteerFactory.createLeiFeng();
        volunteer.sweep();
        volunteer.wash();
        volunteer.buyRice();
    }

}