Go语言设计模式实战：享元模式详解

package main

import "fmt"

// 勋章结构体
type Badge struct {
	name string
}

// 创建勋章实例
func NewBadge(name string) *Badge {
	return &Badge{name: name}
}

// 勋章享元结构体
type BadgeFlyweight struct {
	badges map[string]*Badge
}

// 返回共享的勋章对象
func (b *BadgeFlyweight) Get(name string) *Badge {
	badge := b.badges[name]
	if badge == nil {
		badge = NewBadge(name)
		b.badges[name] = badge
	}
	return badge
}

// 勋章享元实例
var badgeFlyweight *BadgeFlyweight

// 用户结构体
type User struct {
	*Badge
}

// 创建用户实例
func NewUser(badgeName string) *User {
	if badgeFlyweight == nil {
		badgeFlyweight = &BadgeFlyweight{badges: make(map[string]*Badge)}
	}
	badge := badgeFlyweight.Get(badgeName)
	return &User{Badge: badge}
}

func main() {
	// 用户1设置粉丝勋章
	user1 := NewUser("fans")
	fmt.Printf("user1:%+v\n", user1)

	// 用户2也设置粉丝勋章，两个用户共享同一个勋章实例
	user2 := NewUser("fans")
	fmt.Printf("user2:%+v\n", user2)

	// 验证用户勋章共享
	fmt.Println(user1.Badge == user2.Badge) // 输出 true
}

user1:&{Badge:0xc000014090}
user2:&{Badge:0xc000014090}
true