1 概念
构建者模式定义：
将一个复杂对象的构建与它的表示分离，使得同样的构建过程可以创建不同的表示
构建者模式包含如下角色：
Product：具体产品ConcreteBuilder：具体建造者Builder：抽象建造者Director：指挥者
读者可以对比以下构建者类图理解各种角色的作用
其中ActorController充当指挥者（Director），ActorBuilder充当抽象建造者，HeroBuilder、AngelBuilder充当具体建造者，Actor充当复杂产品。其中ActorController充当指挥者（Director），ActorBuilder充当抽象建造者，HeroBuilder、AngelBuilder和DevilBuilder充当具体建造者，Actor充当复杂产品。
2 go语言实现
2.1 定义产品角色
type Actor struct {
Type string
Sex string
Face string
Costume string
HairStyle string
}
func (a Actor) ShowActorInfo() {
fmt.Println("角色类型: ", a.Type)
fmt.Println("角色性别: ", a.Sex)
fmt.Println("角色面容: ", a.Face)
fmt.Println("角色服装: ", a.Costume)
fmt.Println("角色发型: ", a.HairStyle)
}
2.2 定义抽象建造者角色
type ActorBuilder interface {
BuildType()
BuildSex()
BuildFace()
BuildCostume()
BuildHairStyle()
CreateActor() Actor
}
2.3 定义具体建造者角色
type HeroBuilder struct {
actor Actor
}
func (hb *HeroBuilder) BuildType() {
hb.actor.Type = "英雄"
}
func (hb *HeroBuilder) BuildSex() {
hb.actor.Sex = "男"
}
func (hb *HeroBuilder) BuildFace() {
hb.actor.Face = "英俊"
}
func (hb *HeroBuilder) BuildCostume() {
hb.actor.Costume = "盔甲"
}
func (hb *HeroBuilder) BuildHairStyle() {
hb.actor.HairStyle = "飘逸"
}
func (hb HeroBuilder) CreateActor() Actor {
return hb.actor
}
type AngelBuilder struct {
actor Actor
}
func (ab *AngelBuilder) BuildType() {
ab.actor.Type = "天使"
}
func (ab *AngelBuilder) BuildSex() {
ab.actor.Sex = "女"
}
func (ab *AngelBuilder) BuildFace() {
ab.actor.Face = "漂亮"
}
func (ab *AngelBuilder) BuildCostume() {
ab.actor.Costume = "白裙"
}
func (ab *AngelBuilder) BuildHairStyle() {
ab.actor.HairStyle = "披肩长发"
}
func (ab AngelBuilder) CreateActor() Actor {
return ab.actor
}
2.4 定义指挥者角色
type ActorController struct {
actorBuilder ActorBuilder
}
func (ac *ActorController) Construct() Actor {
ac.actorBuilder.BuildType()
ac.actorBuilder.BuildFace()
ac.actorBuilder.BuildCostume()
ac.actorBuilder.BuildSex()
ac.actorBuilder.BuildHairStyle()
return ac.actorBuilder.CreateActor()
}
由于go中没有析构函数，使用New方法创建一个指挥者
func NewActorController(ab ActorBuilder) *ActorController {
return &ActorController{
actorBuilder: ab,
}
}
2.5 demo调用
package main
import (
"design_pattern/builder"
"fmt"
)
func main() {
var tActor builder.Actor
tHeroBuilder := builder.HeroBuilder{}
tAngelBuilder := builder.AngelBuilder{}
tActorController := builder.NewActorController(&tHeroBuilder)
tActor = tActorController.Construct()
tActor.ShowActorInfo()
fmt.Println("========================")
tActorController = builder.NewActorController(&tAngelBuilder)
tActor = tActorController.Construct()
tActor.ShowActorInfo()
}
读者可以结合代码对照前面的UML类图理解
