工厂模式学习记录

　　工厂模式（Factory Pattern）

　　

　　1，Shape接口的定义

package factory;

public interface Shape {
    void draw();
}    

　　2，Circle实现Shape接口

package factory;

public class Circle implements Shape {

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

}

　　3，Rectangle实现Shape接口

package factory;

public class Rectangle implements Shape {

    @Override
    public void draw() {
        System.out.println("draw a rectangle");
    }

}

　　4，Square实现Shape接口

package factory;

public class Square implements Shape {

    @Override
    public void draw() {
        System.out.println("draw a Square");
    }

}

　　5，工厂方法类ShapeFactory

package factory;

public class ShapeFactory {
     static final String CIRCLE="circle";
     static final String SQUARE="square";
     static final String RECTANGLE="rectangle";
    public Shape getShape(String type){
        if(type.equals(CIRCLE)){
            return new Circle();
        }else if(type.equals(RECTANGLE)){
            return new Rectangle();
        }else if(type.equals(SQUARE)){
            return new Square();
        }else{
            return null;
        }
        
    }
}

　　6，工厂的使用Demo

package factory;

public class FactoryDemo {
    public static void main(String[] args) {
        ShapeFactory factory= new ShapeFactory();
        
        Shape shape=factory.getShape(ShapeFactory.CIRCLE);
        shape.draw();
    }
}