工厂模式

1、简单工厂模式

工厂模式（Factory Pattern）是 Java 中最常用的设计模式之一。这种类型的设计模式属于创建型模式，它提供了一种创建对象的最佳方式。

在工厂模式中，我们在创建对象时不会对客户端暴露创建逻辑，并且是通过使用一个共同的接口来指向新创建的对象。

package factory;

public interface Shape {
    void draw();
}

package factory;

public class Square implements Shape{

    @Override
    public void draw() {
        System.out.println("Inside Square:draw() is running");
    }

}

package factory;

public class Rectangle implements Shape{

    @Override
    public void draw() {
        System.out.println("Inside Rectangle:draw() method is running!!!!");
    }
}

package factory;

public class Circle implements Shape{

    @Override
    public void draw() {
        System.out.println("Inside Circle:draw() method is running!!!!");
    }

}

package factory;

public class ShapeFactory {
    public Shape getShape(String type) {
        if(type == null) {
            return null;
        }
        if(type.equalsIgnoreCase("Rectangle")) {
            return new Rectangle();
        }
        if(type.equalsIgnoreCase("Square")) {
            return new Square();
        }
        if(type.equalsIgnoreCase("Circle")) {
            return new Circle();
        }
        return null;
    }
}

package factory;

public class ShapeFactoryTest {
    public static void main(String[] args) {
        ShapeFactory shape = new ShapeFactory();
        Shape rectangle = shape.getShape("Rectangle");
        rectangle.draw();
        Shape square = shape.getShape("Square");
        square.draw();
        Shape circle = shape.getShape("Circle");
        circle.draw();
        
    }
}

结果打印；
Inside Rectangle:draw() method is running!!!!
Inside Square:draw() is running
Inside Circle:draw() method is running!!!!

 2、抽象工厂模式

抽象工厂模式（Abstract Factory Pattern）是围绕一个超级工厂创建其他工厂。该超级工厂又称为其他工厂的工厂。这种类型的设计模式属于创建型模式，它提供了一种创建对象的最佳方式。

在抽象工厂模式中，接口是负责创建一个相关对象的工厂，不需要显式指定它们的类。每个生成的工厂都能按照工厂模式提供对象。

//创建一个形状接口
public interface Shape {
    void draw();
}

//创建一个形状接口
public interface Color {
    void fill();
}

public class Circle implements Shape{

    @Override
    public void draw() {
        System.out.println("Inside Circle:画圆");
    }

}


public class Red implements Color{

    @Override
    public void fill() {
        System.out.println("红色");
    }

}

package absfactory;
//颜色工厂
public class ColorFactory extends AbstractFactory{

    public Color getColor(String color) {
         if(color == null){
             return null;
          }        
          if(color.equalsIgnoreCase("RED")){
             return new Red();
          } else if(color.equalsIgnoreCase("GREEN")){
             return new Green();
          } else if(color.equalsIgnoreCase("BLUE")){
             return new Blue();
          }
          return null;
    }

    public Shape getShape(String shape) {
        return null;
    }

}

//形状工厂
package absfactory;

public class ShapeFactory extends AbstractFactory {

    
    public Color getColor(String color) {
        // TODO Auto-generated method stub
                return null;
    }

    public Shape getShape(String shapeType) {
        if(shapeType == null){
             return null;
          }        
          if(shapeType.equalsIgnoreCase("CIRCLE")){
             return new Circle();
          } else if(shapeType.equalsIgnoreCase("RECTANGLE")){
             return new Rectangle();
          } else if(shapeType.equalsIgnoreCase("SQUARE")){
             return new Square();
          }
          return null;
    }

}

package absfactory;

//为Color和Shape对象创建抽象类来获取工厂
public abstract class AbstractFactory {
    public abstract Color getColor(String color);
    public abstract Shape getShape(String shape);
}

//创建一个工厂创造生成器类，通过传递形状或颜色信息来获取工厂
//可以认为是工厂的工厂
public class FactoryProducer {
    public static AbstractFactory getFactory(String code) {
        if(code.equalsIgnoreCase("shape")) {
            return new ShapeFactory();
        }else if(code.equalsIgnoreCase("color")) {
            return new ColorFactory();
        }
        return null;
    }
}

package absfactory;
//测试
public class AbstractFactoryTest {
    public static void main(String[] args) {
        //获取形状工厂
        AbstractFactory shapeFactory = FactoryProducer.getFactory("shape");
        //获取形状为Circle的对象
        Shape circle = shapeFactory.getShape("circle");
        //调用draw（）方法
        circle.draw();
        
        //获取颜色工厂
        AbstractFactory colorFactory = FactoryProducer.getFactory("color");
        //获取颜色为红色的对象
        Color red = colorFactory.getColor("red");
        red.fill();
    }
}

打印输出：
Inside Circle:画圆
红色