模式定义
使用共享技术无效地反对大量细粒度的对象
类图
利用场景
如果零碎有大量相似的对象，能够应用享元模式
长处
如果零碎有大量相似的对象，能够节俭大量的内存及 CPU 资源
要点总结
要点总结
- 如果零碎有解耦实现对象的代价问题，Flyweight 次要解决面向对象的代价问题，个别不涉及面向对象的抽象性问题
- Flyweight 采纳对象共享的做法来升高零碎中对象的个数，从而升高细粒度对象给零碎带来的内存压力。在具体实现方面，要留神对象状态的解决
- 对象的数量太大从而导致对象内存开销加大 – 什么样的数量才算大？这须要咱们认真的依据具体利用状况进行评估，而不能凭空臆断
Go 语言代码实现
工程目录
flyweight.go
package Flyweight
type FlyWeight struct {Name string}
func NewFlyWeight (name string) *FlyWeight{return &FlyWeight{Name: name}
}
type FlyWeightFactory struct {pool map[string]*FlyWeight
}
func NewFlyWeightFactory() *FlyWeightFactory {return &FlyWeightFactory{pool: make(map[string]*FlyWeight)}
}
func (f *FlyWeightFactory) GetFlyWeight (name string) *FlyWeight {weight, ok := f.pool[name]
if !ok {weight = NewFlyWeight(name)
f.pool[name] = weight
}
return weight
}flyweight_test.go
package Flyweight
import "testing"
import "github.com/stretchr/testify/assert"
func TestFlyWeightFactory_GetFlyWeight(t *testing.T) {factory := NewFlyWeightFactory()
hong := factory.GetFlyWeight("hong beauty")
xiang := factory.GetFlyWeight("xiang beauty")
assert.Len(t, factory.pool, 2)
assert.Equal(t, hong, factory.pool["hong beauty"])
assert.Equal(t, xiang, factory.pool["xiang beauty"])
}