golang 创建型设计模式 抽象工厂

缘起

最近复习设计模式
拜读谭勇德的<<设计模式就该这样学>>
本系列笔记拟采用golang练习之

抽象工厂

抽象工厂模式（Abstract Factory Pattern）指提供一个创建一系列相关或相互依赖对象的接口，无须指定它们具体的类。意思是客户端不必指定产品的具体类型，创建多个产品族中的产品对象。
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抽象工厂vs工厂方法

• 抽象工厂是创建一系列对象, 且这些对象之间可能存在相关性. 工厂方法通常是创建单一类别的对象

场景

• 某智能家居场景, 需要通过app统一控制各种设备
• 目前支持智能灯(ILight)和空调(IAirConditioner)
• 不同厂家, 通过提供不同的抽象工厂实现, 接入系统, 提供各种设备的控制

设计

• 定义ISmartDevice接口, 作为所有智能设备的基础接口
• 定义ILight, 抽象智能灯的接口
• 定义IAirConditioner, 抽象空调的接口
• 定义ISmartFactory, 抽象工厂接口, 定义创建智能灯 - CreateLight, 和创建空调 - CreateAirConditioner的方法
• 定义并实现IFactoryRegistry, 提供厂商标识符到抽象工厂实例的全局注册表
• 创建"mijia"子目录, 接入"mijia"厂商的智能灯和空调
  • tMijiaLight, 实现ILight接口
  • tMijiaAirConditioner, 实现IAirConditioner接口
  • tMijiaFactory, 实现ISmartFactory接口, 并在init方法中注册到全局的工厂注册表
• 创建"redmi"子目录, 接入"redmi"厂商的智能灯和空调

abstract_factory_test.go

单元测试

package patterns

import (
    af "learning/gooop/creational_patterns/abstract_factory"
    "testing"

    // 引入并注册厂商"mijia"
    _ "learning/gooop/creational_patterns/abstract_factory/mijia"

    // 引入并注册厂商"redmi"
    _ "learning/gooop/creational_patterns/abstract_factory/redmi"
)

func Test_AbstractFactory(t *testing.T) {
    config := make([]*af.DeviceInfo, 0)
    config = append(config, af.NewDeviceInfo(1, "客厅灯", af.DeviceTypeLight, "mijia", "ML-100"))
    config = append(config, af.NewDeviceInfo(2, "餐厅灯", af.DeviceTypeLight, "redmi", "RL-45"))
    config = append(config, af.NewDeviceInfo(11, "主卧空调", af.DeviceTypeAirConditioner, "mijia", "MA-15"))
    config = append(config, af.NewDeviceInfo(12, "次卧空调", af.DeviceTypeAirConditioner, "redmi", "RA-10"))

    for _,info := range config {
        factory := af.DefaultFactoryRegistry.Get(info.Vendor())
        if factory == nil {
            t.Errorf("unsupported vendor: %s", info.Vendor())

        } else {
            switch info.GetType() {
            case af.DeviceTypeLight:
                e,light := factory.CreateLight(info)
                if e != nil {
                    t.Error(e.Error())
                } else {
                    _ = light.Open()
                    _,_ = light.GetLightMode()
                    _ = light.SetLightMode(1)
                    _,_ = light.GetLightMode()
                    _ = light.Close()
                }
                break

            case af.DeviceTypeAirConditioner:
                e,ac := factory.CreateAirConditioner(info)
                if e != nil {
                    t.Error(e.Error())
                } else {
                    _ = ac.Open()
                    _,_ = ac.GetTemperature()
                    _ = ac.SetTemperature(26.5)
                    _,_ = ac.GetTemperature()
                    _ = ac.Close()
                }
                break
            }
        }
    }
}

测试输出

$ go test -v abstract_factory_test.go 
=== RUN   Test_AbstractFactory
tMijiaLight.Open, &{1 客厅灯 Light mijia ML-100}
tMijiaLight.GetLightMode, 0
tMijiaLight.SetLightMode, 1
tMijiaLight.GetLightMode, 1
tMijiaLight.Close, &{1 客厅灯 Light mijia ML-100}
tRedmiLight.Open, &{2 餐厅灯 Light redmi RL-45}
tRedmiLight.GetLightMode, 0
tRedmiLight.SetLightMode, 1
tRedmiLight.GetLightMode, 1
tRedmiLight.Close, &{2 餐厅灯 Light redmi RL-45}
tMijiaLight.Open, &{11 主卧空调 AirConditioner mijia MA-15}
tMijiaAirConditioner.GetTemperature, 0
tMijiaAirConditioner.SetTemperature, 26.5
tMijiaAirConditioner.GetTemperature, 26.5
tMijiaLight.Close, &{11 主卧空调 AirConditioner mijia MA-15}
tRedmiAirConditioner.Open, &{12 次卧空调 AirConditioner redmi RA-10}
tRedmiAirConditioner.GetTemperature, 0
tRedmiAirConditioner.SetTemperature, 26.5
tRedmiAirConditioner.GetTemperature, 26.5
tRedmiAirConditioner.Close, &{12 次卧空调 AirConditioner redmi RA-10}
--- PASS: Test_AbstractFactory (0.00s)
PASS
ok      command-line-arguments  0.002s

ISmartDevice.go

抽象智能设备的基础接口

package abstract_factory

type ISmartDevice interface {
    ID() int
    Name() string

    Open() error
    Close() error
}

ILight.go

抽象智能灯的接口, 继承ISmartDevice接口, 并添加灯光模式的控制方法

package abstract_factory

type ILight interface {
    ISmartDevice

    GetLightMode() (error, int)
    SetLightMode(mode int) error
}

IAirConditioner.go

抽象空调的接口, 继承ISmartDevice接口, 并添加温度控制的方法

package abstract_factory

type IAirConditioner interface {
    ISmartDevice

    GetTemperature() (error, float64)
    SetTemperature(t float64) error
}

DeviceInfo.go

智能设备的配置信息

package abstract_factory

type DeviceInfo struct {
    iID int
    sName string
    sType DeviceType
    sVendor string
    sModel string
}

type DeviceType string
const DeviceTypeLight DeviceType = "Light"
const DeviceTypeAirConditioner DeviceType = "AirConditioner"

func NewDeviceInfo(id int, name string, devType DeviceType, vendor string, model string) *DeviceInfo {
    return &DeviceInfo{
        id, name, devType, vendor, model,
    }
}

func (me *DeviceInfo) ID() int {
    return me.iID
}

func (me *DeviceInfo) Name() string {
    return me.sName
}

func (me *DeviceInfo) Vendor() string {
    return me.sVendor
}

func (me *DeviceInfo) GetType() DeviceType {
    return me.sType
}

FactoryRegistry.go

从工厂标识符到抽象工厂实例的全局注册表

package abstract_factory


var DefaultFactoryRegistry = newFactoryRegistry()


type IFactoryRegistry interface {
    Set(vendor string, factory ISmartFactory)
    Get(vendor string) ISmartFactory
}

type tSimpleFactoryRegistry struct {
    mFactoryMap map[string]ISmartFactory
}

func newFactoryRegistry() IFactoryRegistry {
    return &tSimpleFactoryRegistry{
        mFactoryMap: make(map[string]ISmartFactory, 0),
    }
}

func (me *tSimpleFactoryRegistry) Set(vendor string, factory ISmartFactory) {
    me.mFactoryMap[vendor] = factory
}

func (me *tSimpleFactoryRegistry) Get(vendor string) ISmartFactory {
    it,ok := me.mFactoryMap[vendor]
    if ok {
        return it
    }
    return nil
}

mijia/MijiaFactory.go

"mijia"厂商实现的工厂类, 在init方法中自动注册到全局注册表

package mijia

import (af "learning/gooop/creational_patterns/abstract_factory")

func init() {
    af.DefaultFactoryRegistry.Set("mijia", newMijiaFactory())
}

type tMijiaFactory struct {
}

func newMijiaFactory() af.ISmartFactory {
    return &tMijiaFactory{}
}

func (me *tMijiaFactory) CreateLight(info *af.DeviceInfo) (error, af.ILight) {
    return nil, newMijiaLight(info)
}

func (me *tMijiaFactory) CreateAirConditioner(info *af.DeviceInfo) (error, af.IAirConditioner) {
    return nil, newMijiaAirConditioner(info)
}

mijia/MijiaLight.go

"mijia"厂商的智能灯实现类

package mijia

import (
    "fmt"
    af "learning/gooop/creational_patterns/abstract_factory"
)

type tMijiaLight struct {
    af.DeviceInfo
    iMode int
}


func newMijiaLight(info *af.DeviceInfo) *tMijiaLight {
    return &tMijiaLight{
        *info, 0,
    }
}

func (me *tMijiaLight) Open() error {
    fmt.Printf("tMijiaLight.Open, %v\n", &me.DeviceInfo)
    return nil
}

func (me *tMijiaLight) Close() error {
    fmt.Printf("tMijiaLight.Close, %v\n", &me.DeviceInfo)
    return nil
}

func (me *tMijiaLight) GetLightMode() (error, int) {
    fmt.Printf("tMijiaLight.GetLightMode, %v\n", me.iMode)
    return nil, me.iMode
}

func (me *tMijiaLight) SetLightMode(mode int) error {
    fmt.Printf("tMijiaLight.SetLightMode, %v\n", mode)
    me.iMode = mode
    return nil
}

mijia/MijiaAirConditioner

"mijia"厂商的空调实现类

package mijia

import (
    "fmt"
    af "learning/gooop/creational_patterns/abstract_factory"
)

type tMijiaAirConditioner struct {
    af.DeviceInfo

    fTemperature float64
}


func newMijiaAirConditioner(info *af.DeviceInfo) *tMijiaAirConditioner {
    return &tMijiaAirConditioner{
        *info, 0,
    }
}

func (me *tMijiaAirConditioner) Open() error {
    fmt.Printf("tMijiaLight.Open, %v\n", &me.DeviceInfo)
    return nil
}

func (me *tMijiaAirConditioner) Close() error {
    fmt.Printf("tMijiaLight.Close, %v\n", &me.DeviceInfo)
    return nil
}

func (me *tMijiaAirConditioner) GetTemperature() (error, float64) {
    fmt.Printf("tMijiaAirConditioner.GetTemperature, %v\n", me.fTemperature)
    return nil, me.fTemperature
}

func (me *tMijiaAirConditioner) SetTemperature(t float64) error {
    me.fTemperature = t
    fmt.Printf("tMijiaAirConditioner.SetTemperature, %v\n", me.fTemperature)
    return nil
}

redmi/RedmiFactory.go

"redmi"厂商实现的工厂类, 在init方法中自动注册到全局注册表. 代码略

redmi/RedmiLight.go

"redmi"厂商的智能灯实现类. 代码略.

redmin/RedmiAirConditioner.go

"redmin"厂商的空调实现类. 代码略.

抽象工厂模式小结

抽象工厂模式的优点
（1）当需要产品族时，抽象工厂可以保证客户端始终只使用同一个产品的产品族。
（2）抽象工厂增强了程序的可扩展性，对于新产品族的增加，只需实现一个新的具体工厂即可，不需要对已有代码进行修改，符合开闭原则。
抽象工厂模式的缺点
（1）规定了所有可能被创建的产品集合，产品族中扩展新的产品困难，需要修改抽象工厂的接口。
（2）增加了系统的抽象性和理解难度。
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