Java工厂模式

最新推荐文章于 2025-05-31 10:47:41 发布

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本文介绍了一个简单的工厂模式示例，定义了Shape接口及其三个子类：Rectangle、Circle和Square，并通过ShapeFactory类来实例化这些形状子类。

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定义一个创建对象的接口

public interface Shape {
    void draw();
}

子类实现接口

public class Rectangle implements Shape{

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

}

public class Cricle implements Shape{

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

}

public class Square implements Shape{

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

}

建立工厂类决定实例化哪一个子类

public class ShapeFactory {
    public Shape getShape(String shapeType){
        if(shapeType == null){
            return null;
        }
        //equalsIgnoreCase 与另一个String比较不考虑大小写
        if(shapeType.equalsIgnoreCase("CRICLE")){
            return new Cricle();
        }else if(shapeType.equalsIgnoreCase("RECTANGLE")){
            return new Rectangle();
        }else if(shapeType.equalsIgnoreCase("SQUARE")){
            return new Square();
        }
        return null;
    }
}

调用

public class FactoryPatternDemo {
    public static void main(String[] args) {
        ShapeFactory shapeFactory = new ShapeFactory();
        Shape shape1 = shapeFactory.getShape("CRICLE");
        shape1.draw();
        Shape shape2 = shapeFactory.getShape("RECTANGLE");
        shape2.draw();
        Shape shape3 = shapeFactory.getShape("SQUARE");
        shape3.draw();

    }
}

输出

这里写图片描述