设计模式-工厂模式golang实现

Created2021-07-11Updated2021-07-11

工厂模式

工厂模式（Factory Pattern）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。

golang实现

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package factorypattern

type Shape interface {
	Draw() string
}

type Rectangle struct{}

func (r *Rectangle) Draw() string {
	return "rectangle"
}

type Square struct{}

func (s *Square) Draw() string {
	return "square"
}

type Circle struct{}

func (c *Circle) Draw() string {
	return "circle"
}

// NewShapeFactory 用于生成Shape接口实例
func NewShapeFactory(t string) Shape {
	if t == "" {
		return nil
	}
	switch t {
	case "rectangle":
		return new(Rectangle)
	case "square":
		return new(Square)
	case "circle":
		return new(Circle)
	}
	return nil
}

test

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package factorypattern

import "testing"

func TestRectangle(t *testing.T) {
	rectangle := NewShapeFactory("rectangle")
	if rectangle == nil {
		t.Fatal("factory new failed")
	}
	res := rectangle.Draw()
	if res != "rectangle" {
		t.Errorf("error, wanted: %v, got: %v", "rectangle", res)
	}
}

func TestSquare(t *testing.T) {
	square := NewShapeFactory("square")
	if square == nil {
		t.Fatal("factory new failed")
	}
	res := square.Draw()
	if res != "square" {
		t.Errorf("error, wanted: %v, got: %v", "square", res)
	}
}

func TestCircle(t *testing.T) {
	circle := NewShapeFactory("circle")
	if circle == nil {
		t.Fatal("factory new failed")
	}
	res := circle.Draw()
	if res != "circle" {
		t.Errorf("error, wanted: %v, got: %v", "circle", res)
	}
}

代码地址

https://github.com/luckylsx/golang-design-mode/tree/main/01_FactoryPattern

参考

https://www.runoob.com/design-pattern/factory-pattern.html

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