DesignPatternFlyweight享元模式

DesignPatternFlyweight享元模式

享元模式从对象中剥离出不发生改变且多个实例需要的重复数据，独立出一个享元，使多个对象共享，从而节省内存以及减少对象数量

一个map[interface{}]interface{}加上断言就能解决的事情，不知道为啥绕一圈

官方代码

package flyweight

import "fmt"

type ImageFlyweightFactory struct {
	maps map[string]*ImageFlyweight
}

var imageFactory *ImageFlyweightFactory

func GetImageFlyweightFactory() *ImageFlyweightFactory {
	if imageFactory == nil {
		imageFactory = &ImageFlyweightFactory{
			maps: make(map[string]*ImageFlyweight),
		}
	}
	return imageFactory
}

func (f *ImageFlyweightFactory) Get(filename string) *ImageFlyweight {
	image := f.maps[filename]
	if image == nil {
		image = NewImageFlyweight(filename)
		f.maps[filename] = image
	}

	return image
}

type ImageFlyweight struct {
	data string
}

func NewImageFlyweight(filename string) *ImageFlyweight {
	// Load image file
	data := fmt.Sprintf("image data %s", filename)
	return &ImageFlyweight{
		data: data,
	}
}

func (i *ImageFlyweight) Data() string {
	return i.data
}

type ImageViewer struct {
	*ImageFlyweight
}

func NewImageViewer(filename string) *ImageViewer {
	image := GetImageFlyweightFactory().Get(filename)
	return &ImageViewer{
		ImageFlyweight: image,
	}
}

func (i *ImageViewer) Display() {
	fmt.Printf("Display: %s
", i.Data())
}


# 测试代码
package flyweight

import "testing"

func ExampleFlyweight() {
	viewer := NewImageViewer("image1.png")
	viewer.Display()
	// Output:
	// Display: image data image1.png
}

func TestFlyweight(t *testing.T) {
	viewer1 := NewImageViewer("image1.png")
	viewer2 := NewImageViewer("image1.png")

	if viewer1.ImageFlyweight != viewer2.ImageFlyweight {
		t.Fail()
	}
}