java - 当具体对象采用不同的构造函数参数时，Java 中的工厂

Question

我正在尝试在 Java 中实现工厂模式。我有一个名为 Shape 的类，其中 Circle 和 Triangle 扩展了。问题是 Shape 构造函数只获得 2 个参数，而 Circle 获得 3 个参数，Triangle 也是如此(我不会在代码部分显示，因为与 Circle 相同)。为了更好地展示它:

    private interface ShapeFactory{
        public Shape create(int x, int y);
    }

    private class CircleFactory implements ShapeFactory{
        public Shape create(float radius, int x, int y){ //error
            return new Circle(radius, x,y);
        }
    }

任何想法如何克服这个问题？我不能从工厂内部接收用户的输入(必须从外部接收)。

谢谢!

Answer 1

你有两个选择:

1) Abstract Factory :

RectangularShape 扩展 Shape

RoundShape 扩展 Shape

和 RectangularShapeFactory 和 RoundShapeFactory

2) Builder (另见有效 Java 中的第 2 项)

public Shape {
    private final int x;
    private final int y;
    private final double radius;

    private Shape(Builder builder) {
        x = builder.x;
        y = builder.y;
        radius = builder.radius;
    }

    public static class Builder {
        private final int x;
        private final int y;
        private double radius;

        public Builder(int x, int y) {
            this.x = x;
            this.y = y;
        }

        public Builder radius(double radius) {
            this.radius = radius;
            return this;
        }

        public Shape build() {
            return new Shape(this);
        }    
    }
}

//in client code 

    Shape rectangle = new Shape.Builder(x,y).build();
    Shape circle = new Shape.Builder(x,y).radius(radiusValue).build();